Pre-Subduction Architecture Controls Coherent Underplating During Subduction and Exhumation (Nevado-Filábride Complex, Southern Spain)

Abstract

The interplay between structural and metamorphic processes operating along the deep plate interface in subduction zones remains elusive as much of the geologic record is recycled into the mantle. In some cases, metamorphosed subducted rocks are underplated and exhumed to the surface, providing critical constraints on structural processes and the rheological evolution of subduction interfaces at convergent margins. One such exhumed high-pressure/low-temperature subduction complex is the Cenozoic Nevado-Filábride Complex (NFC) in Southern Spain. This study presents new data from the NFC that elucidate the syn-metamorphic deformation, stacking, and underplating of continental slivers along the subduction interface. The structurally lowest NFC dominantly comprises lithologically monotonous Paleozoic metamorphic basement rocks recorded by apatite U-Pb ages and shows no evidence for large-scale internal duplications suggesting it behaved as a coherent basement succession during subduction. In contrast, structurally higher levels of the NFC are characterized by the stacking of older-on younger coherent slices and distinctly different metamorphic ages. These relationships document syn-subduction structural repetitions and tectonic stacking of imbricate thin slivers (∼100s m) during subduction underplating. Structurally higher levels of the NFC exhibit both Eocene and Miocene metamorphic zircon rims and apatite ages, along with microstructures indicative of relatively higher temperature metamorphism. Large-scale underplating and antiformal stacking of slivers in the subduction channel can provide buoyancy forces to underplate and assist exhumation. We demonstrate that the presubduction stratigraphic architecture is a key control on the style and timing of deformation and metamorphism, facilitating coherent subduction underplating.

Full text

1. Introduction
Subduction zones are the primary driver of plate tectonics and facilitate material recycling between Earth's
surface and interior (e.g., Stern, 2002), but also pose geological hazards at convergent continental margins,
including earthquakes and volcanic eruptions. The processes that take place on the heterogeneous subduction
interface are often imprinted in the rock record. While most of this record is lost into the deep mantle or other-
wise not accessible to directly study, some of these subducted rocks end up getting exhumed and exposed back at
Abstract The interplay between structural and metamorphic processes operating along the deep plate
interface in subduction zones remains elusive as much of the geologic record is recycled into the mantle. In
some cases, metamorphosed subducted rocks are underplated and exhumed to the surface, providing critical
constraints on structural processes and the rheological evolution of subduction interfaces at convergent margins.
One such exhumed high-pressure/low-temperature subduction complex is the Cenozoic Nevado-Filábride
Complex (NFC) in Southern Spain. This study presents new data from the NFC that elucidate the
syn-metamorphic deformation, stacking, and underplating of continental slivers along the subduction interface.
The structurally lowest NFC dominantly comprises lithologically monotonous Paleozoic metamorphic
basement rocks recorded by apatite U-Pb ages and shows no evidence for large-scale internal duplications
suggesting it behaved as a coherent basement succession during subduction. In contrast, structurally higher
levels of the NFC are characterized by the stacking of older-on younger coherent slices and distinctly different
metamorphic ages. These relationships document syn-subduction structural repetitions and tectonic stacking of
imbricate thin slivers (∼100s m) during subduction underplating. Structurally higher levels of the NFC exhibit
both Eocene and Miocene metamorphic zircon rims and apatite ages, along with microstructures indicative
of relatively higher temperature metamorphism. Large-scale underplating and antiformal stacking of slivers
in the subduction channel can provide buoyancy forces to underplate and assist exhumation. We demonstrate
that the presubduction stratigraphic architecture is a key control on the style and timing of deformation and
metamorphism, facilitating coherent subduction underplating.
Plain Language Summary Subduction zones are tectonic boundaries where one rigid lithospheric
plate sinks underneath another. At the interface between the two plates, rocks experience intense temperature,
pressure, and stress conditions during metamorphism, causing deformation. The geologic record of
these processes is often not accessible unless these rocks return to the surface. Our study targets one such
exposure in Southern Spain, the Nevado-Filábride Complex, which records deformation and structural mixing
from subduction and subsequent transfer to the overriding plate. We perform geochronologic analyses to
determine the age of zircon overgrowths that reveal the timing of metamorphism. Additionally, we date apatite
minerals and examine deformation relationships at the microscopic scale to approximate the temperature
conditions that these rocks experienced. We synthesize these new results with previously established
geochronology of zircon grains from the same region that collectively show evidence for the large-scale
structural stacking of coherent rock slivers during deformation. The stacking pattern is observed only in the
weak upper stratigraphic successions, while the deeper unit remained internally intact and experienced a lesser
degree of metamorphism. Our results argue that the style and distribution of deformation during subduction are
strongly influenced by the original stratigraphic architecture and properties prior to subduction.
POULAKI ETAL.
© 2023. The Authors.
This is an open access article under
the terms of the Creative Commons
Attribution License, which permits use,
distribution and reproduction in any
medium, provided the original work is
properly cited.
Pre-Subduction Architecture Controls Coherent Underplating
During Subduction and Exhumation (Nevado-Filábride
Complex, Southern Spain)
Eirini M. Poulaki1,2 , Daniel F. Stockli1 , and Brandon D. Shuck3
1Department of Geological Sciences, The University of Texas at Austin, Austin, TX, USA, 2Department of Earth and
Space Sciences, University of Washington, Seattle, WA, USA, 3Lamont-Doherty Earth Observatory, Columbia University,
Palisades, NY, USA
Key Points:
• Two main Cenozoic metamorphic
events were recorded in the Betic
subduction zone in Eocene and
Miocene by zircon and apatite
• Imbrication and thrust faults coeval
with underplating developed along the
subduction interface
• Subduction of thick coherent
metamorphic basement enhances
buoyancy forces and contributes to
exhumation
Supporting Information:
Supporting Information may be found in
the online version of this article.
Correspondence to:
E. M. Poulaki,
epoulaki@uw.edu
Citation:
Poulaki, E. M., Stockli, D. F., & Shuck,
B. D. (2023). Pre-subduction architecture
controls coherent underplating
during subduction and exhumation
(Nevado-Filábride Complex, Southern
Spain). Geochemistry, Geophysics,
Geosystems, 24, e2022GC010802. https://
doi.org/10.1029/2022GC010802
Received 21 NOV 2022
Accepted 14 FEB 2023
Corrected 6 APR 2023
This article was corrected on 6 APR
2023. See the end of the full text for
details.
Author Contributions:
Conceptualization: Eirini M. Poulaki,
Daniel F. Stockli
Data curation: Eirini M. Poulaki
10.1029/2022GC010802
Special Section:
Insights into Subduction Zone
Processes from Models and
Observations of Exhumed
Terranes
RESEARCH ARTICLE
1 of 33

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
2 of 33
the Earth's surface as subduction complexes in collisional orogenic belts, accretionary prisms, and the back-arc
regions of convergent margins. They are particularly well exposed in the Mediterranean realm, including the
Greek Cyclades, the Alps, and the Betic-Rif Cordillera in Spain and Morocco (e.g., Jolivet etal.,2003), as well
as the Cordilleran margin from California to Alaska. Unlocking the information recorded in these subduction
complex rocks is essential for understanding fundamental subduction processes, such as underplating, fluid-
rock interactions, and metamorphic mineral transformations. Importantly, the timing of fluid expulsion from
dehydration reactions in the rock record is critical for understanding the nature of episodic tremors and slow slip
earthquake events along the deeper (30–60km) subduction interface (e.g., Behr & Bürgmann,2021; French &
Zhu,2017; Tarling etal.,2019). However, the length scales of mixing and stacking of incoming rock units in the
subduction channel during subduction, as well as the conditions and style of deformation along the subduction
plate boundary, remain poorly understood.
Several conceptual and numerical models exist for the nature and mechanics of underplating and exhumation
of high-pressure (HP) rocks along the subduction interface. These include forced advection, channel flow, and
mélange formation through a subduction channel (Burov etal.,2001; Cloos,1982; Gerya etal.,2002; Shreve &
Cloos,1986), crust-mantle delamination (Chemenda etal.,1995), and slab roll-back with coherent subduction
and underplating (Brun & Faccenna,2008). All of these models involve the upward vertical displacement of
deeply subducted material and decoupling from the downgoing slab. The subsequent removal of overburden to
exhume and expose HP rocks can be related to backflow up the shear zone (Cloos,1982; Shreve & Cloos,1986)
due to erosion (e.g., Brandon etal., 1998; Ring et al., 1999), extension (e.g., Platt,1986,1993) or both (e.g.,
Royden, 1993). Even though underplating has been clearly imaged and documented at shallower depths of
10–20km using geophysical data (Collot etal., 2008; Melnick et al.,2006), our knowledge of underplating
at greater depths of ∼30–60km is sparser; although HP rocks, metamorphosed at 10–20kbar, are commonly
exposed in subduction complexes. In addition, while Andean-style convergent margins are dominated by the
subduction of pelagic and trench sediment and seamounts, Mediterranean-style subduction involves the under-
thrusting of exhumed mantle, and variably attenuated continental crust arranged along shorter, fragmented
plate boundaries. This may be anomalous compared to typical Andean-style subduction paradigms but likely
represented a common style during Tethyan, Rheic, or Iapetus subduction (e.g., Nance etal.,2012; Stampfli &
Borel,2002; Van Hinsbergen etal.,2020).
Reconstructing the presubduction crustal anatomy and stratigraphy from the initial deposition and characterizing
how they are subsequently modified is critical for understanding the nature, style, and spatial scales of deforma-
tion during subduction and the coupling between the downgoing and overriding plates. Rocks that end up being
subducted and underplated likely experience multiple stress regimes and deformation styles due to changing
tectonic conditions during subduction and exhumation. Hence, most of the presubduction geologic record is typi-
cally overprinted and initial stratigraphic characteristics have been annealed. However, as our knowledge of these
regimes improves, there have been recent discoveries and methodological advances that allow us to reconstruct
the presubduction configurations in the exhumed rock record and provide insights into subduction processes. A
few examples include preserved rift-related structures in the Alps and Pyrenees (Jammes etal.,2009) as well as in
the Betic Cordillera (Martin-Rojas etal.,2009). Studies from the subduction complexes in the Cyclades, Greece
(Kotowski etal., 2022; Poulaki et al., 2019; Seman,2016) show that the presubduction architecture of these
exhumed terranes can be discerned. Discriminating presubduction versus syn-subduction processes is essential
to better understand the spatial and temporal scales of fault and shear zone motions, rheological conditions, and
the specific pressure and temperature conditions during subduction zone metamorphism.
This study focuses on the Cenozoic subduction evolution in the Western Mediterranean by analyzing the
Nevado-Filábride Complex (NFC) of the Internal Betic Cordillera in Southern Spain, which represents a
well-exposed subduction complex. The Mediterranean region involves numerous tectonic segments with subduct-
ing microplates of variable architecture and behavior. The geologic record of past subduction events is unusually
well preserved in collisional and backarc regions as a result of the segmented nature of these tectonic systems
and the attempted underthrusting of abundant isolated continental crustal slivers and blocks. High-resolution
geochronology and petrographic field observations coupled with microstructural analyses constitute powerful
tools to investigate the geologic remnants of subduction zones and directly inform the timing, conditions, and
styles of tectono-metamorphic processes. We demonstrate that this approach can unravel the syn-subduction
evolution and the nature and style of structural stacking of HP terranes during progressive subduction under-
plating. Leveraging zircon and apatite U-Pb geochronology combined with microstructural/Electron Backscatter
Formal analysis: Eirini M. Poulaki
Funding acquisition: Daniel F. Stockli
Investigation: Eirini M. Poulaki, Daniel
F. Stockli, Brandon D. Shuck
Methodology: Eirini M. Poulaki
Resources: Daniel F. Stockli
Supervision: Daniel F. Stockli
Validation: Daniel F. Stockli, Brandon
D. Shuck
Visualization: Eirini M. Poulaki,
Brandon D. Shuck
Writing – original draft: Eirini M.
Poulaki
Writing – review & editing: Daniel F.
Stockli, Brandon D. Shuck

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
3 of 33
Diffraction (EBSD) analyses and field observations, our data show that the initial stratigraphy of the NFC was
rearranged during subduction, underplating, and exhumation throughout the Cenozoic and provide precise timing
constraints on the record of metamorphism and initiation of the Betic subduction in the Western Mediterranean.
2. Geologic Setting
2.1. Mediterranean Subduction Complexes
Subduction zones in the Mediterranean region have a unique architecture that differentiates them from other
subduction zones across the world. The major tectonic events of the Mediterranean include convergence and moun-
tain building during the Carboniferous Variscan orogeny followed by rifting during the Triassic/Jurassic and subse-
quent opening of domains of the Neo-Tethys Ocean (Asti etal.,2019; Pedrera etal.,2020). In the Late Cretaceous,
convergence between Africa and Europe, due to the anticlockwise rotation of Africa, triggered the Alpine orogeny
with segmented subduction systems initiating from east to west (e.g., Dewey etal.,1989; Faccenna etal.,2004;
Jolivet etal.,2003). Isolated oceanic and rifted continental blocks were subducted, underplated, and later exhumed
during trench retreat (e.g., Brun & Faccenna,2008; Lonergan and White,1997; Scott & Lister,1992). Due to
deformation associated with collision and complicated outcrop geometries of the subduction complex rocks in
alpine settings, as well as the disappearance of numerous micro-oceanic domains, the rapid evolution of the region
makes it challenging to use traditional methods to reconstruct the geologic history of the Mediterranean.
One of the most well-exposed subduction complexes in the western Mediterranean is the NFC. The NFC contains
the geologic record of the formation and breakup of Pangea and underwent subsequent subduction and exhu-
mation in the Cenozoic. At present, the NFC outcrops along major folded elongated extensional domes in the
Betic Cordillera of southern Spain (Martínez-Martínez et al., 2002). The Betic Cordillera forms the northern
component of the arcuate Betic-Rif orogenic belt, whereas the southern counterpart comprises the Rif Mountain
belt in northern Morocco. The general architecture of the Betic-Rif system was formed with the subduction of
oceanic and continental crust due to convergence between Africa and Eurasia, followed by westward migration
of the trench and coeval collision of the Alboran domain with the African and South Iberian paleomargins (e.g.,
Balanyá etal.,1997; Booth-Rea etal.,2005,2007). Between the Betic-Rif Cordillera lies the Alboran upper plate
domain in the westernmost Mediterranean ocean, which largely comprises of the Alpujarride Complex and has
also experienced metamorphism and crustal shortening until the Early Miocene (e.g., Esteban etal.,2011; Platt
etal.,1998). Offshore regions of the Alboran basin in the Betics and Rif were below sea level since the Early to
Late Miocene (e.g., de la Peña etal.,2021; Rodríguez-Fernández etal.,2011).
Subduction-related volcanism was sparse throughout Cenozoic convergence but was active from ∼18 to 6Ma
and is currently exposed in southeastern Spain, providing evidence of the subduction geometry in the Miocene
(Duggen etal., 2003,2004,2008; Varas-Reus etal.,2017). The tectonic evolution of this system is complex
because of the exposure of subduction-related terranes, both subcontinental and oceanic mantle sequences, and a
strong component of oblique and transcurrent tectonics. Additionally, there is evidence for a significant amount
of trench retreat that drove subsequent extension in the overriding plate (Faccenna etal.,2004; Gutscher,2012;
Lonergan & White,1997) and lateral slab tearing at the edges of the system along the Betics and Rif (e.g., Capella
etal.,2020; de Lis Mancilla etal.,2015; García-Castellanos & Villaseñor,2011; Levander etal.,2014), leading
to the present-day near-vertical position of the slab beneath the Alboran Sea (Bezada etal.,2013).
2.2. The Structural and Stratigraphic Rearrangement of the Nevado-Filábride Complex
The geologic terranes of the Betic Cordillera are grouped into Internal and External zones. The External zones
contain Mesozoic to Miocene sedimentary rocks deposited along the Iberian continental paleomargin. While the
Internal Betics have been divided into three main groups from top to bottom: the unmetamorphosed Maláguide,
and the metamorphosed Alpujárride and NFC (Balanyá & García-Dueñas,1987). Initially, they were all considered
to be part of the Alboran domain (i.e., the allochthonous terrane translated between Iberia and Africa; Balanyá &
García-Dueñas,1987); however, more recent studies have suggested the NFC formed along the southern margin of the
Iberian Peninsula (e.g., Booth-Rea etal.,2015; Gómez-Pugnaire etal.,2004,2012; Jabaloy-Sánchez etal.,2018,2021;
Kirchner etal.,2016; López Sánchez-Vizcaíno etal.,2001; Platt etal.,2006; Poulaki & Stockli,2022).
Within the NFC, there have been significant disagreements regarding the subdivision of units based on their age,
metamorphic grade and contacts among the different lithologies. Based on Martínez-Martínez etal.(2002), there

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
4 of 33
are at least three different tectonic units separated by metamorphic grade with shear zones marking their contacts:
the basal Ragua unit (Gómez-Pugnaire & Franz,1988), Calar Alto, which includes the Tahal formation, and the
upper Bédar-Macael unit. Another well-accepted subdivision considers two main units: a lower homogeneous
Veleta unit and an upper, more heterogeneous Mulhacén succession, which includes metamorphosed mafic and
ultramafic rocks (Puga etal.,2000,2002; Sanz de Galdeano & Santamaría-López,2019).
Detrital zircon studies have shown that the Veleta unit is Carboniferous and older in age (Jabaloy-Sánchez
et al., 2018, 2021; Poulaki & Stockli,2022; Santamaría-López & Sanz de Galdeano, 2018). Carboniferous
ages of the Veleta unit are also supported by conodont fossils (Rodríguez-Cañero etal., 2018). Additionally,
Laborda-López etal.(2015) identified Early Devonian fossil assemblages in graphite marbles intercalated in the
graphite schist of the Veleta unit. In contrast, detrital zircon data show that the overlying Mulhacén succession is
Late Carboniferous/Early Permian to Early Jurassic (Jabaloy-Sánchez etal.,2018,2021; Poulaki & Stockli,2022).
More recently, Poulaki & Stockli(2022) performed abundant detrital zircon dating and found that the NFC is
Paleozoic to Early Jurassic metasedimentary sequence preserving the record of sedimentation from the Variscan
orogeny to Neo-Tethys opening. The largest part of the Tahal formation dates to the Permian-Triassic/Early
Jurassic (Poulaki & Stockli,2022) with Jurassic basic intrusions (Puga etal.,2005). The Bédar-Macael subunit
represents the structurally highest parts of the NFC. The Bédar-Macael includes various types of schist primar-
ily Permian in age (Poulaki & Stockli,2022), thick carbonate units that are generally assumed to be Triassic or
Jurassic in age, as well as ophiolitic rocks that have been dated as Jurassic. In this study, we use the latter unit
subdivision with a basal Veleta unit and overlying Mulhacén succession since it better reflects the initial protolith
ages (Figure1). We utilize the previous chronostratigraphic framework established by Poulaki & Stockli(2022)
and integrate it with microstructural observations and zircon and apatite U-Pb data to investigate the style and
timing of deformation during subduction and underplating of the NFC units.
Previous work has already indicated a potential for tectonic relationships within the NFC. The first studies in
the region described the contacts between these units as thrust faults (Egeler & Simon,1969; García-Dueñas
Figure 1. Geologic map of the Nevado-Filábride Complex illustrating the main lithologic units, sample locations, and presence/absence of Cenozoic metamorphic
zircon and apatite. Light blue shows Eocene ages, yellow shows Miocene ages, and black colors show the absence of zircon rims or non-Cenozoic apatite (from IGME
Spain maps, and modified after Poulaki and Stockli(2022)).

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
5 of 33
etal.,1988; Kampschuur & Rondeel,1975), but other studies suggest the contacts could be mylonitic shear zones
developed during nappe tectonics with thrust contacts in between the units that later cut through these contacts as
low angle normal fault shear zones (e.g., Booth-Rea etal.,2005; Comas etal.,1999; Crespo-Blanc,1995; Martín-
ez-Martínez & Azañón, 1997; Martínez-Martínez et al.,2002, 2010). More recently, Sanz de Galdeano and
Santamaría-López(2019) proposed that the Veleta-Mulhacén contact is stratigraphic and transitional in nature
and argued for the lack of structural discrepancies between the units. The revaluation of the MDA calculations
from Poulaki & Stockli(2022) indicated at least eight structural repetitions, and here we compared these ages
with petrological data, temperature conditions, textural fabrics, and field observations across the NFC to reeval-
uate the potential for significant internal structural features related to subduction deformation and underplating
processes (Figure S5 in Supporting InformationS1).
2.3. Cenozoic Tectono-Metamorphic Evolution of the Betic Cordillera
The tectonic processes that led to the closure of the Neo-Tethys ocean in the western Mediterranean and the Betic-
Rif orogen are currently debated, with scenarios including (a) a northwest-dipping subduction zone (e.g., Bezada
etal.,2013; Booth-Rea etal.,2007; Brun & Faccenna,2008; Carminati etal.,2012; Chertova etal.,2014; Faccenna
etal.,2004; Rosenbaum etal.,2002), (b) An east-dipping subduction zone followed by reversal and northwest-dipping
subduction (Frizon de Lamotte etal.,2000; Rehault etal.,1984), (c) a south-east dipping subduction zone (Behr &
Platt,2012) or (d) contemporaneous southward and northward two-sided subduction (Bessière, Augier, etal.,2021;
Bessière, Jolivet, etal.,2021; Vergés & Fernàndez,2012). Regardless of the initial direction of subduction, many
studies agree on the subsequent rotation of the system with east-dipping subduction and westward trench retreat.
Recent geophysical studies have imaged the Iberian Moho at depths of 65km, which implies substantial crustal
thickening (de Lis Mancilla etal., 2015). Seismicity data show a steeply dipping slab with earthquakes continu-
ing to 120–150km depth (e.g., Civiero etal.,2020; Heit etal.,2017). Geochemical and geophysical evidence of
a Miocene volcanic arc related to subduction are evidenced in southeastern Spain (e.g., Booth-Rea etal., 2018;
Casalini etal., 2022; Gómez de la Peña etal., 2020). Additionally, rocks with HP metamorphic signatures are
exposed in the NFC, and the subcontinental Ronda peridotite is preserved in southern Iberia emplaced between crus-
tal units of the Alpujarride nappe stack. Collectively, these lines of evidence indisputably confirm the involvement of
a subduction zone in late Cenozoic convergence between Africa and Iberia; although, the timing of subduction initi-
ation and evolution of the system remains obscured. During the Middle Miocene, westward trench retreat of the Betic
subduction zone involved slab rollback and lateral migration to its current configuration (e.g., Moragues etal.,2021).
The NFC represents the structurally lowest outcropping sequence of the Internal Betics that underwent penetra-
tive deformation and metamorphism during subduction and subsequent exhumation to the surface. Estimated P/T
conditions of the NFC have led to the suggestion of at least two distinct metamorphic events with initial HP/LT
conditions followed by a second metamorphic event. The nature of the second metamorphic event is controversial
with some studies suggesting reheating at lower pressure (Bakker etal., 1989; Booth-Rea etal.,2015; B. Li &
Massonne,2018; Santamaría López etal., 2019) while other studies suggest cooling during decompression or
isothermal decompression (Augier, Agard, etal.,2005; Augier, Jolivet, & Robin,2005; Behr & Platt,2012). Meta-
morphic studies have focused on the metapelites (Ruiz-Cruz etal.,2015), mafic, ultramafic, and felsic igneous rocks
(Augier, Agard, etal.,2005; Augier, Jolivet, & Robin,2005; Gómez-Pugnaire etal.,1994; López-Sánchez-Vizcaíno
etal.,2001,2005; Padrón-Navarta etal.,2010; Puga etal.,2000,2002; Ruiz-Cruz etal.,2015; Santamaría-López
etal.,2019). While these studies all commonly support HP/LT followed by a second metamorphic event, they
strongly disagree on the absolute pressures and temperatures experienced by the rocks, as summarized in combined
P/T trajectories by Santamaría-López etal.(2019). Studies suggest that the lowest NFC Veleta unit has experi-
enced temperatures from 550 to 590°C with pressures from 1.3 to 1.8GPa (Augier, Agard, etal.,2005; B. Li &
Massonne,2018; Santamaría-López etal.,2019) with the majority of studies suggesting that it has not exceeded
∼530°C. The intermediate Calar-Alto unit experienced temperatures from 550 to 650°C with pressures from 1.0 to
2.2GPa (Augier, Agard, etal.,2005; B. Li & Massonne,2018; Santamaría-López etal.,2019), and the uppermost
Bédar-Macael unit records the highest temperatures and pressures from 600 to 750°C and 1.1–2.2GPa (Augier,
Agard, etal., 2005; Bakker et al., 1989; Behr & Platt, 2012; Gómez-Pugnaire & Fernández-Soler,1987; Puga
etal., 2002; Santamaría-López etal., 2019; Vissers etal.,1995) with the majority of recent studies suggesting
temperatures <600°C (e.g., Augier, Agard, etal.,2005; Behr & Platt,2012; Santamaría-López etal.,2019).
Geochronologic constraints for NFC metamorphism generally show two distinct events, although more data point
toward a younger event in the Miocene.
40Ar/
39Ar dating on phengite (Augier, Agard, etal.,2005; Augier, Jolivet,

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
6 of 33
& Robin,2005) and sodic amphibole (Monié et al., 1991) supports HP metamorphism around ∼40–48 Ma.
Conversely, Lu-Hf garnet dating (18–14Ma: Platt etal.,2006), U-Pb dating on zircon (17–15Ma; Gómez-Pugnaire
etal.,2012; Lopez Sanchez-Vizcaıno etal.,2001) and multimineral Rb/Sr isochron dating (20–13Ma) argue for
younger HP metamorphism (Kirchner etal.,2016). However, B. Li and Massonne(2018) proposed an HP/LT
event during the Eocene (∼40Ma) and a second P/T loop with exhumation from 24.1±0.8Ma. More recently,
Aerden etal.(2022) separated garnets based on their magnetic fraction and were able to obtain Sm-Nd ages in
Eocene (∼35Ma) age as well as Miocene ones, and Porkoláb etal.(2022) with Ar/Ar data also found distinct
events dated at 38–27Ma and 22–12Ma. The final exhumation of the NFC and Alpujárride was accommodated
with the formation of low-angle normal faults and strike-slip transfer faults at ∼12Ma for the NFC (Augier,
Agard, etal.,2005; Azañón etal.,2015; Galindo-Zaldívar etal.,1993,2003; Madarieta-Txurruka etal.,2021;
Platt etal., 2005; Reinhardt et al.,2007) and 22–18 Ma for Alpujárride (e.g., Platt et al., 2005). Today, the
NFC outcrops along the central-eastern Betic Cordillera and form three major E–W trending antiforms (Sierra
Alhamilla, Sierra Nevada, and Sierra de Los Filabres), providing ample exposure of the NFC extensional domes
for field studies and spatially extensive sample collection throughout the Internal Betics.
3. Methods and Results
In this study, we focus on the Cenozoic metamorphic and structural evolution of the NFC. We use a densely
sampled data set across all structural levels of the NFC throughout the Betic Cordillera. Detrital zircon analyses
of these samples were previously presented in Poulaki and Stockli(2022), which used provenance source signa-
tures to determine the Paleozoic to Mesozoic depositional history and presubduction stratigraphy of the NFC.
Here, we utilize this new stratigraphic framework and the spatial age constraints coupled with new apatite and
zircon geo/thermochronology and microstructural analyses to study when and how units of the NFC were modi-
fied during subduction and exhumation.
Apatite petrochronology is a great tool to set relative temperature constraints on rocks that have experienced
subduction-related metamorphism since its closure temperature of Pb has been determined by laboratory exper-
iments to ∼360–550°C (Cherniak etal.,1991; Chew & Spikings,2021; Smye etal.,2018; Watson etal.,1985).
Additionally, apatite records deformation and fluid interactions and can be partially recrystallized and record
multiple deformation and alteration events (e.g., Odlum & Stockli,2020; Odlum etal.,2022). Even though few
studies have investigated apatite U-Pb systematics in subduction rocks, Henrichs etal.(2018) showed that apatite
is fully reset within its partial retention zone. Recent advances in zircon U-Pb geochronology have shown that
zircon can decipher metamorphic events during the different stages of subduction metamorphism from prograde
to peak to retrograde metamorphism by investigating metamorphic overgrowths (e.g., Kohn & Kelly,2018;
Poulaki etal.,2021; Rubatto,2002). Lastly, quartz and feldspar microstructures with EBSD analyses complement
these chronometers and provide relative temperature constraints.
3.1. Metamorphic Zircon
Of the 71 samples previously analyzed from the NFC in Poulaki & Stockli(2022), 33 of them yielded Cenozoic
zircon overgrowths and are presented and discussed in this study (Figure1). These zircon grains were analyzed by
laser-ablation inductively coupled plasma mass-spectrometry depth-profiling following the procedures of Marsh
& Stockli(2015), which resulted in a continuous radiometric sequence from thin rims to zircon cores. We used
GJ1 as the primary zircon standard (601.7±1.3Ma; Jackson etal.,2004) and Plešovice (337.1±0.4Ma; Sláma
etal., 2008) as the secondary standard. Data reduction was carried out with IgorPro-based Iolite 3.4 software
(Paton etal.,2010). By using depth-profiling techniques, we are able to manually differentiate and interpret age
plateaus in the U-Pb concentrations and distinguish zones between cores, mixing ages, and rims of the zircon
grains. After depth profiling, several grains were polished, and we collected Cathodoluminescence images (CL).
Three grains were chosen for the collection of 2D zircon elemental mapping techniques as further described
in Poulaki etal. (2021). We discarded zircon rim ages with more than 30% discordance between
206Pb/
238U
and
207Pb/
235U ages and reported our data with 2σ propagated errors.
3.1.1. Zircon U-Pb
Calculated U-Pb ages of zircon metamorphic overgrowths range from 100Ma to 12Ma with the population
majority spanning between 60Ma and 17Ma (Figures2a–2c). From Sierra Nevada, 11 samples from the upper

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
7 of 33
Figure 2. Concordia diagrams for the metamorphic zircon overgrowths grouped by location and age showing two generations of zircon rims in Eocene/Paleocene
and Miocene. Color bars show U concentration [ppm]. Kernel Density estimate plots use the corrected ages by using the Stacey and Kramers(1975) common lead
correction. “N” represents the sample number and “n” is the number of grains. Panels (a–c) have been grouped based on the location where the samples were collected.

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
8 of 33
structural levels exhibited zircon metamorphic overgrowths. These samples are within the Tahal (Permian-Triassic
protolith), Bédar-Macael (Carboniferous-Jurassic protolith), and uppermost Veleta (Devonian-Carboniferous
protolith). Two main age peaks are found in the zircon age distributions clustered around Paleocene/Eocene
(Figure2ai) and Miocene (Figure 2aii). One sample, a quartz mica phyllite (18SSN13) from the uppermost
Veleta, shows a single rim age of the Eocene. The absence of zircon rims is prominent in the central parts of the
orogen and mostly within the Veleta unit as well as from four samples from the Mulhacén succession (Figure1).
From Sierra de los Filabres, 14 samples from the NFC exhibit a wider range of zircon rim ages with a minor age
mode at ∼70Ma. Clustering the Paleocene/Eocene ages together yields an average age of ∼55Ma (Figure2biii). The
Miocene peak for these zircon metamorphic overgrowths is well defined with an average concordant age of ∼18Ma
(Figure2biv). The majority of the samples with zircon rims derive from the eastern Sierra de los Filabres exposes the
uppermost units. Out of 14 samples that preserve Cenozoic zircon overgrowths, three of them have only Eocene rims
(19SSF08, 19SSF06, and 18SSF10) and two have only Miocene rims (19SSF12, 19SSF07). The lack of Cenozoic
zircon rims is observed in the largest part of the Veleta unit as well as in five samples from the Mulhacén succession.
Similar to the samples collected from Sierra Nevada and Sierra de los Filabres, eight samples with Cenozoic zircon
overgrowths from Sierra Alhamilla show two distinct peaks in the Eocene and Miocene. Most samples from the upper
structural sections within the Bédar-Macael and uppermost Veleta (19SSA08) exhibit both generations of rims. Impor-
tantly, samples from the majority of the Veleta unit do not preserve any Cenozoic metamorphic zircon rims.
The spread of zircon metamorphic rim ages does not necessarily reflect the extent of the metamorphic event since
they could also be influenced by discordance, inheritance, and common lead because of the thin nature of the
overgrowths. Metamorphic rims older than 80Ma are not further discussed since these data are sparse and do not
represent a statistically robust portion of the collective zircon rim population. Furthermore, convergence between
Africa and Iberia begins around ∼60–100Ma; hence, it is unlikely that they are related to Cenozoic subduction
metamorphism, which is the focus of our study.
3.1.2. Zircon CL Images and 2D U-Pb Maps
To better constrain the spatial architecture of zircon overgrowths, we collected CL data to image zonation patterns
and 2D LA-ICP-MS elemental maps to constrain their radiometric ages. Several representative grains from three
orthogneisses (19SSA10, 19SSN12A, 18SSF08) with Eocene and Miocene rims revealed by depth-profiling
data were selected for CL analyses. These grains were hand-picked, rotated, and mounted to double-sided sticky
tape, covered with epoxy, and polished for analysis. CL images reveal that Eocene rims are generally thin with
homogeneous textures (Figure3a and Figure S1 in Supporting InformationS1). These rims are darker than their
corresponding magmatic cores and follow the oscillatory zoning geometry of the grain cores but preserve differ-
ent textural morphology and are overall euhedral. In contrast, Miocene rims appear thicker and more heterogene-
ous with complex porous spongy textures (Figure3b and Figure S1 in Supporting InformationS1). These rims
are asymmetric with variable thickness around the grain edges and are brighter than their corresponding cores.
Three representative grains from sample 19SSA10 were selected for 2D elemental mapping. These analyses provide
a 2D map of age constraints throughout the zircon grain and thus reveal their isotopic morphology. In Figure3a
(19SSA10_16) the Eocene rim is only ∼10μm thick and has low (<0.05) Th/U with high U concentrations. The
core of this grain is Permian and clear zoning is observed in the corresponding CL image with low U (∼530 ppm)
concentration and high Th/U. Zircon grains 19SSA10_52 and 19SSA10_60 (Figures3b and3c) have Miocene rims
enclosing a Permian core. These rims are as thick as 50μm in places with lower Th/U (∼0.01) relative to their cores
(>0.06). CL images show that these rims appear to have variable textures, with some regions growing along the
oscillatory zoning, but others seemingly intruding and overprinting core zonation with porous structures.
3.2. Apatite U-Pb Geochronology and CL Imaging
Apatite U-Pb data were collected from samples from the lower- and upper-unit successions and analyzed both
in situ on thin sections as well as on grain separates. Prior to in situ analyses, we collected element dispersive
Elemental Dispersive Spectroscopy (EDS) maps to measure Ca, P, Si, and Ti and identify apatite within our thin
sections. Afterward, we aligned the EDS map to the laser stage to target the mapped apatite grains. A 30μm spot
with a total of 200 ablation shots was used for in situ thin section analyses, while a 40μm spot with 300 ablation
shots was used for apatite grain separates. For selected grains, we performed 2D elemental maps using 15μm
and following the same methodology as for the zircon maps. For all three methods, MAD apatite (Thomson

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
9 of 33
Figure 3. (a–c) CL images and zircon two-dimensional maps showing
238U/
206Pb age, Th/U values, and [U] concentration. (d
and e) CL images and apatite two-dimensional maps showing [U] and [Th] concentrations. The laser spot size for zircon is 6
and 15μm for apatite. Pixel sizes correspond to spot size and data have been interpolated.

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
10 of 33
etal.,2012, in-house TIMS age of 472.4±0.7Ma) was used as the primary standard, and McClure Mountain
(523.5±1.5 Ma; Schoene & Bowring, 2006) as the secondary standard. Raw data from apatite analyses are
plotted in Tera-Wasserburg Concordia diagrams (Figures4 and5; Tera and Wasserburg,1972; Vermeesch,2018).
In our samples from the NFC, we distinguish four distinct groups of apatite grains based on their ages and
textures. The first group is defined by late Paleozoic and early Mesozoic U-Pb ages, which are older than
subduction initiation and convergence between Africa and Iberia. Samples in this group are solely from the
Veleta unit, with two in situ analyses (19SSN01, 19SSN02) and two from grain separates (18SSN09, 18SSA02).
Graphitic mica-schist samples (18SSN09, n=13; 18SSA02, n=44) with Carboniferous MDAs yielded apatite
U-Pb ages of 379.1± 11.4 Ma and 307.6 ±2.6 Ma, respectively, and a common Pb composition of ∼0.84
(Figures4a and4c). A Carboniferous graphitic quartz mica schist (19SSN01, n=44) yielded in situ apatite
ages of 152.3±7.0Ma. Similarly, in situ apatite from a metabasite within the Veleta unit yielded a Jurassic age
of 197.0±6.0Ma (Figure4b; Poulaki & Stockli,2022). CL images from these apatite grains show an overall
Figure 4. Pre-Cenozoic, Group 1 apatite U-Pb data plotted on Tera-Wasserburg Concordia plots (error ellipses represent single analyses in two sigma error) (a and b) in
situ on thin sections analyses (c and d) grain separates.

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
11 of 33
Figure 5. Subduction related metamorphic (Groups 2, 3, 4) apatite U-Pb data plotted on Tera Wasserburg Concordia plots (error ellipses represent single analyses in
two sigma error). CL images showing representative apatite grains.

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
12 of 33
homogeneous grain structure with minor patches of bright spots on grain surfaces (Figure4 and Figure S2 in
Supporting InformationS1).
The second group is characterized by Eocene apatite cores and rims. This group contains two Permian tourmaline-bearing
orthogneisses from the Mulhacén succession in the Sierra Nevada (19SSN12A, n=484; 19SSN20, n=88) and were
previously found to have zircon crystallization ages of ∼275Ma (Poulaki & Stockli,2022). Apatite U-Pb ages from
grain separate from these samples are Eocene with ages at 45.0±2.2 and 42.5±5.8Ma, respectively, and a common
Pb composition of ∼0.7 (Figures5a and5b). Due to the complicated structure revealed by the CL images and the high
common Pb composition in sample 19SSN12A, we exported and plotted the data in 3-s increments as described in
Odlum & Stockli(2020). CL images from these grains exhibit bright irregular cores with darker rims. Additionally, a
network of fractures crosscutting in irregular orientations is observed on many of these grains (Figure3d). Hence, it
appears that these bright fractures postdate apatite rim formation. With our depth-profiling method for these grains,
we can subdivide the raw data acquisition window into distinct plateaus, which yields an Eocene age for the apatite
core. However, we were not able to obtain ages for the rims due to low U and high concentration of common Pb.
In our 2D U-Pb maps, the apatite core and rims can be easily differentiated by differences in the U and Th concen-
trations (Figures3d and3e). In both grains from samples 19SSN12A and 18SSN20, the cores are highly enriched
in U (∼60–100 ppm) in comparison to the rims (∼10–30 ppm). In contrast, Th concentration in grains from sample
19SSN12A is the same in rims and cores (∼20 ppm) but higher in cores (∼20 ppm) than rims (∼5 ppm) in grains
from sample 19SSN20 (Figures2d and2e).
The third group of apatite grains were collected from metasedimentary rocks from the Mulhacén succession at Sierra
Nevada and are distinguished by Miocene apatite U-Pb ages. A Triassic protolith garnet quartz mica schist (18SSN14,
n=123) was analyzed in situ and yielded an age of 9.4±4.9Ma and a common Pb composition of 0.8. A Devonian
quartz rich schist (19SSN11, n=341) yielded a U-Pb apatite age of 16.2±3.7Ma and a common Pb composition of
0.83. Similar to sample 19SSN12A, we exported these data in 3-s increments. CL images from these grains show an
amorphous core with many dark and light patches and bright rims around the cores (Figures5c and5d).
The fourth and final apatite group is distinguished by partially reset apatite. Grains for this group are from samples
collected from Sierra Alhamilla and Sierra de los Filabres. Our data show that these grains are partially recrystallized,
evidenced by large dispersion on individual analyses within the Tera-Wasserburg plots (Figures5e and5f). By isolat-
ing the different ellipse clusters within the age spectra, we can reconstruct the oldest and youngest events the apatite
has recorded from the grouped lower intercepts. A calcite mica quartz schist (19SSF09) from Sierra de los Filabres
displays a lower youngest intercept of 47.1±16.7Ma and a lower oldest intercept of 270.1±11.1Ma (Figure5e).
Orthogneiss samples from Sierra Alhamilla (18SSA10) yielded a younger lower intercept of 48.6±2.2Ma and an
older lower intercept of 293.2±12.6Ma (Figure5f). CL images from these grains show a darker core with lighter
patches and a very bright rim with a porous, spongy texture (Figure5f). The thickness of rims varies from 1 to
2μm up to 20μm. Last, a Devonian quartzite (19SSN07) in the southern Sierra Nevada exhibited an apatite age of
40.9±17.1Ma (Figure S3 in Supporting InformationS1). Due to the large error attributed to low U concentration
and high amounts of common Pb, we do not lump this sample into the four apatite groups.
3.3. Microstructural Analyses
Since the relationship between temperature and deformational patterns expressed in quartz and feldspar microstruc-
tures is well established, we conducted detailed observations on samples from Sierra Nevada to complement apatite
U-Pb thermo-chronometer data. Collectively, these tools provide estimates of the relative temperatures (∼400–550°C)
that these rocks experienced during their polymetamorphic evolution and place timing constraints on strain accom-
modation during these events. Microstructures were qualitatively assessed with petrographic microscopes and quanti-
fied using EBSD techniques. All samples for these analyses were cut perpendicular to the foliation and parallel to the
lineation. EBSD mapping was performed at the Geomaterials Characterization and Imaging Facility at the University
of Texas at Austin. We used AzTec software to clean the raw quartz and feldspar EBSD data by removing wild spikes
and plotted the data using the MTEX software package (Bachmann etal.,2010). In this section, we describe the
textural observations in structural order from the lower to upper units of the NFC.
Two graphitic quartz mica schists from the Veleta unit (19SSN01, 19SSN09) show similar microstructural
characteristics. Both exhibit ∼1mm euhedral quartz crystals within microlithons (Figures 6a, 6b, 6e, and 6f).
Misorientation maps from these samples record limited internal strain, with a few quartz grains preserving some

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
13 of 33
Figure 6. (a and b) Graphitic quartz mica schist from the Veleta unit in cross-polarized light and with the gypsum plate collected from South-West Sierra Nevada,
showing quartz grains and lack of Lattice Preferred Orientation (LPO). (c and d) Electron Backscatter Diffraction (EBSD) data from that same sample showing the lack
of LPO (MI=MisorientationIndex). (e and f) Graphitic quartz mica schist from the Veleta unit collected from West Sierra Nevada, showing quartz grains with gypsum
plate in highlighting the strong LPO separated by mica domains. (c and d) EBSD data from the same sample in panels (e and f) showing a lack of LPO. (i) Orthogneiss
from South Sierra Alhamilla. (j) Quartz and feldspar microstructures in sample 18SSFO8 showing grain boundary migration and bulging.

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
14 of 33
subgrains and minor undulatory extinction and minor evidence of grain boundary migration. However, the major-
ity of the quartz crystals in these samples show no evidence of intracrystalline plasticity. We also found evidence
for normal grain growth with 120° angles in quartz grains. Mica in these samples are aligned along the quartz
ribbons. EBSD data show that these samples have absent or weak Lattice Preferred Orientation (LPO) as defined
by their Misorientation index (M) (M=0.0038 and M=0.0068; Figures6c, 6d, 6g, and6h), but there is a Shape
Preferred Orientation (SPO) parallel to the foliation. In sample 19SSN01, albite crystals contain graphitic inclu-
sions that define microfolds (Figure S4 in Supporting InformationS1) and show some subgrains and minor undu-
latory extinction but no evidence of major plastic deformation within the grains. Albite grains contain inclusion
graphite trails and exhibit evidence of rotated textures relative to the main foliation orientation.
Samples from the higher parts of the Veleta unit contain garnet porphyroblasts, in contrast to the lower sections
that do not contain garnets, as documented by this work and previous studies (e.g., Behr & Platt,2012; Sanz de
Galdeano & Santamaría-López,2019). A quartz mica schist with feldspar and minor garnet and a quartz-rich
schist (19SSN03) collected from within the uppermost Veleta close to the Veleta-Tahal contact have quartz crys-
tals with distinct layers of elongated ribbons with grain boundary migration and bulging (Figures7a and 7b).
Additionally, quartz forms large ameboid grains and has a strong LPO (M=0.1036), as shown by the mis2mean
maps (Figures7c and7d), which are indicative of moderate temperatures (∼500°C; Passhier & Trouw,2005).
Similar structures have been observed by Behr and Platt(2013) in Sierra Alhamilla. Albite porphyroblasts in this
sample are euhedral with minor subgrains but overall do not show evidence of recrystallization (Figure7b). A
Devonian quartzite from within the Bédar-Macael unit (19SSN11) also exhibits a moderate LPO (M=0.0833)
with bulging in quartz and grain boundary rotation (Figures7e, 7f, and7g). However, the presence of feldspar
grains in between quartz grains in this sample could potentially hinder the development of quartz LPO fabrics.
Within the Tahal schist, a garnet mica schist (18SSN14) preserves significantly different microstructures than
previous samples from lower stratigraphic domains. Garnet porphyroblast growth predates the current foliation,
and they have well-defined inclusion trails with quartz, mica, and minor rutile. Quartz within the main foliation
shows evidence of grain boundary migration and recrystallization. Albite crystals show significant dynamic
recrystallization and breakdown due to mica growth and subgrain rotation (Figures7h and7i), with evidence of
subgrains indicating temperatures >550°C. Within the uppermost Bédar-Macael unit, two tourmaline-bearing
orthogneisses were further investigated (19SSN12A, 18SSN20, 18SSF08). Feldspar grains have discontinuous
undulatory extinction, subgrains, and bulging, but no dynamic recrystallization is observed (Figure6j). Quartz
within these samples shows grain boundary migration with ameboid structures and many subgrains (Figure6j).
4. Discussion
4.1. Stratigraphic Rearrangement: Current Structural Position of NFC Units
Subduction complex rocks are highly deformed and often have experienced multiple metamorphic episodes,
causing much of their initial crustal anatomy and stratigraphic architecture to be overprinted and obscured. Some
rocks from subduction complexes appear to have been deformed and/or underplated in a mélange style with
significant levels of lateral flow and mixing, resulting in a complex loss of presubduction context (e.g., Angiboust
etal.,2013; Cloos & Shreve,1988). These HP rocks are often accreted to the overriding plate in a complex
fashion and subsequently exhumed, involving orogenesis, uplift, erosion, and syn- and postorogenic extension.
Hence, constraining the temporal and spatial scales of progressive deformation and underplating as well as meta-
morphism along the deep subduction interface is challenging solely based on large-scale field observations.
Recent breakthroughs combining geochronology with detailed field observations in the Cyclades of the Hellenic
subduction zone revealed large-scale stratigraphic coherency of these deformed rocks with structural imbrication
and stacking of tectonic slivers (Kotowski etal.,2022; Poulaki etal.,2019; Seman,2016). In this study, we lever-
age this approach by combining detailed geochronologic analyses and utilizing the presubduction stratigraphic
reconstructions of the NFC based on MDAs established by Poulaki & Stockli(2022). Their work showed that
the provenance signature of the NFC is remarkably stable throughout its depositional history and largely records
unroofing of late Paleozoic Variscan basement and early Mesozoic Alpine Tethyan rifting. The consistent young-
ing of MDAs within tectonic slivers, regional lithological correlations, and dating of igneous orthogneisses
provide strong evidence that these zircon ages provide a robust chronostratigraphic framework for the NFC. For
this study, we interpret MDA patterns from 12 regional transects across the NFC to assess how these rocks have
been structurally rearranged and stacked during Cenozoic subduction and exhumation.

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
15 of 33
Figure 7. (a and b) Quartz structures in sample 19SSN03 showing grain boundary migration and bulging. (c and d) Mis2mean map and pole diagrams indicating a
moderate Lattice Preferred Orientation (MI=Misorientation Index). (e and g) Mis2mean map and pole diagrams for sample 19SSN11. (f) Feldspar bulging and quartz
grain boundary migration in cross polars in sample 19SSN11. (h and i) Garnet bearing, sample 18SSN14 showing albite crystals breaking appearing recrystallization
and subgrain rotation.

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
16 of 33
Throughout the structural column of the NFC, we identified at least three MDA reversals indicative of older
on top of younger rocks, and eight total reversals within our transects (Figure8). These reversals show that the
original stratigraphic architecture of the units has been modified, requiring a structural explanation, such as the
presence of either recumbent folds or thrust fault imbrication. While small-scale folds are present, large-scale
recumbent folds (Arend Zevenhuizen,1989; García-Dueñas etal.,1988; Martínez-Martínez etal.,2002,2010)
should result in age reversals across the fold axis and symmetry of lithological and age progressions from old to
young and to old again. Instead, we consistently observe younging MDA estimates within each separated sliver
and abrupt changes back to old ages at lithological boundaries. These relationships are best explained by the
presence of discrete thrust faults that imbricate coherent and upright tectonic slivers, forming a nappe stack and
preserving original stratigraphic packages that are young within each individual fault-bounded sliver. Addition-
ally, we find consistent foliation patterns across the MDA-defined sliver boundaries (Figure8; Ruiz-Fuentes &
Aerden,2018) but differences in metamorphic pressure/temperature conditions and metamorphic and maximum
depositional ages (this study; e.g., Santamaría-López etal.,2019). Collectively, these lines of evidence argue for
the presence of multiple thrust repetitions and stacking within the NFC. Below, we integrate the MDAs, micro-
structures, field observations, and metamorphic ages to discuss where, when, and how these large-scale (∼100s
m) deformation features formed and the implications for subduction underplating processes.
The majority of the Veleta unit exhibits monotonous MDAs ranging from Early to Late Carboniferous and we inter-
pret this unit as a thick coherent Variscan basement block that did not experience any significant post-Variscan inter-
nal imbrication and hence largely preserves its presubduction architecture. However, along the uppermost parts of
Veleta unit in the Sierra Nevada and Sierra de Los Filabres, we find Cambrian/Devonian rocks intercalated with
Carboniferous strata, and in some cases, sandwiched between Permian strata (Figures8a, 8b, and8e). This age rever-
sal corresponds to the base of the Calar-Alto unit mapped by Martínez-Martínez etal.(2010). The observed Devo-
nian on top of Carboniferous relationships could be explained as thrusts or large folds formed during the Variscan
orogeny. However, we observe similar relationships with Devonian atop Permian rocks in the western Sierra Nevada
and southern Sierra de los Filabres. Additionally, the first age reversal above the Veleta coincides with the position
of the Dos Picos shear zone, where hotter rocks where emplaced over lower-temperature ones at a late stage in the
metamorphic evolution of the NFC complex (Augier, Agard, etal.,2005; B. Li & Massonne,2018). Together, these
evidence show that these tectonic contacts postdate the Variscan deformation in the Carboniferous and imply thrust
imbrication during Cenozoic convergence and subduction (Figures1 and8).
Moving up section, the relationship between the overlying Mulhacén succession and the Veleta unit is spatially varia-
ble. While in most locations, we observe a continuous depositional relationship from Carboniferous to Permian rocks
(Figures1 and8f), supporting similar findings by Sanz de Galdeano and Santamaría López(2019), along the western
domain of Sierra Nevada and Sierra Alhamilla, Carboniferous rocks of Veleta are in direct contact with Triassic
strata of the Tahal unit of the Mulhacén Succession (Figures1 and8a). This hiatus could be interpreted as a synrift
unconformity in the depositional record, although a more complicated structural relationship between the Veleta and
Mulhacén units has been proposed (Ruiz-Fuentes & Aerden,2018). Alternatively, this age relationship could also
likely be related to extensional shearing during late-stage exhumation (Martínez-Martínez etal.,2002).
The Mulhacén succession exhibits the most variability in lithologies and MDAs, with mixed metabasites, marbles,
schists, and orthogneisses, and ages ranging from Early Permian to Early Jurassic. There is ample evidence for
older on younger MDA relationships within the Mulhacén succession, indicating thrust relationships and perva-
sive structural imbrication. Several locations show slivers of Permian rocks wedged above Triassic but below
Devonian strata (Figures8a and8b). Similar tectonic slivers have been previously identified in the eastern Sierra
de los Filabres and were interpreted as three distinct thrust sheets with Paleozoic on top of Mesozoic cover (de
Jong,1993a,1993b; Porkoláb etal.,2022). Our new data confirm this interpretation and show Permian rocks of
the lower unit thrust above Triassic strata (Tahal formation; Figure8d). We also observed similar imbrication
patterns in the upper structural portions of the Sierra Nevada. Comparable age reversal patterns are present in
the western and southwestern Sierra Nevada, where Permian rocks are structurally juxtaposed against Triassic
and Devonian slivers. The dominant S2 foliation in all slivers consistently dips direction toward N/NW in West
Sierra Nevada and NNE in Sierra de los Filabres (Figures8d and8e). Ruiz-Fuentes and Aerden(2018) showed
that S1 and S2 foliations associated with subduction fabrics are slightly more variable within the Mulhacén and
along the Mulhacén/Veleta contact, whereas they are more consistent throughout the Veleta unit, supporting our
observations that Mulhacén has more internal structural complexity.

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
17 of 33
Figure 8.

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
18 of 33
Thrust relationships, similar to those in the NFC, have also been identified in the adjacent Alpujárride Complex
by field observations (Balanyá etal.,1997; Booth-Rea etal.,2005; Rossetti etal.,2005) and recent geochron-
ologic data (Poulaki & Stockli,2022), showing Carboniferous graphitic schist structurally overlaying Permian
phyllites and schists. Hence, both the NFC and Alpujárride units have experienced subduction imbrication and
subsequent underplating and exhumation.
4.2. Pre-Cenozoic Metamorphism of the Veleta Basement
The integration of zircon and apatite U-Pb and microstructural analyses strongly suggests that the NFC Veleta unit
primarily records presubduction deformation and metamorphism during the late Paleozoic Variscan orogeny, despite
being subducted and exhumed during the Cenozoic. In general, apatite grains are rare in the lithologies of the Veleta
unit, and only four samples yielded apatite grains. Two samples from Veleta in Sierra Nevada and Sierra Alhamilla
gave Carboniferous apatite U-Pb ages (Figure 4). While these metasedimentary protoliths are characterized by
Carboniferous MDAs and cosmopolitan detrital zircon spectrum spanning 3Ga to 300Ma (Poulaki & Stockli,2022),
the Carboniferous/Devonian apatite U-Pb ages appear to record Variscan tectonism and metamorphism.
A metabasite and graphitic mica schist from the Veleta unit in the southern Sierra Nevada both yielded the earliest
Jurassic apatite U-Pb ages (Figures4a and4b). The metabasite age likely represents the timing of magmatic crystalli-
zation and has been interpreted as recording dike emplacement as part of the Central Atlantic Magmatic Province and
coeval with early Jurassic rifting (Poulaki & Stockli,2022). The Late Jurassic apatite U-Pb age from the Carboniferous
country rock records subsequent rifting and break-up during the formation of the Alpine Tethys. This age is consistent
with previously reported zircon ages from metabasites within the NFC (Puga etal.,2002) and has been attributed to
Jurassic rifting in the Western Mediterranean following the Variscan Orogeny (e.g., Saspiturry etal.,2019). Inter-
estingly, Cenozoic metamorphic zircon rims in the Veleta unit are sparse or entirely absent (Figures1, 8c, and8f).
In terms of metamorphic paragenesis, the lower part of the Veleta unit is dominantly composed of quartz, feldspar,
muscovite, biotite, chlorite, and rutile, consistent with these rocks not having exceeded midgreenschist facies meta-
morphic conditions. Despite evidence of later static recrystallization with some polygonal quartz grains, EBSD data
show a very weak or absent LPO fabric in quartz grains. While experimental work has shown that quartz LPO is
commonly preserved even when rocks undergo static recrystallization (Heilbronner & Tullis,2002), the evidence
for some static recrystallization of quartz does not support the annealing or complete removal of a preexisting fabric.
Additionally, Veleta samples are characterized by the lack of evidence for intracrystalline plasticity in quartz and
recrystallization of feldspar (Figures6a–6h). Similar microstructures have been observed in the Veleta unit in the
Sierra de los Filabres (González-Casado etal.,1995) and Sierra Alhamilla (Behr & Platt,2013). The latter study
attributed the lack of LPO and presence of SPO to pressure-solution creep during subduction and exhumation with
the presence of free water at estimated temperatures of 490–530°C (Behr & Platt,2012).
Our new apatite U-Pb data from the majority of Veleta yield robust preCenozoic ages, suggesting that this unit did
not experience temperatures >450°C during subduction-related metamorphism and escaped major fluid alteration
necessary for apatite recrystallization. We propose that the Veleta unit experienced high-temperature metamorphism
(>∼500°C) during the late Paleozoic Variscan tectonic events but remained largely unaltered during Cenozoic subduc-
tion. Presubduction metamorphism of the Veleta unit may have affected the rheology and deformation behavior of
this section of the NFC during Cenozoic subduction compared to the overlying post-Variscan NFC strata, which show
evidence for younger apatite ages and hence higher temperature subduction metamorphism.
4.3. Cenozoic Metamorphism During Subduction and Underplating
Systematic LA-ICP-MS depth profiling analyses revealed two primary metamorphic events in the Eocene and
Miocene recorded by metamorphic zircon rim ages and metamorphic apatite grains (Figures2 and5). A Miocene
Figure 8. (a and b) Cross-section from southwest and west Sierra Nevada, indicating lithologies and interpreted blue letters indicate apatite U-Pb ages, yellow letters
indicate Maximum Depositional Ages. In cross section (a) North stands at coordinates 37°0′1.12″N, 3°15′41.85″W and south stands at coordinates 36°55′32.30″N,
3°17′19.33″W. In cross section (b) East stands at coordinates 37°3′21.93″N, 3°21′56.53″W and west at coordinates 37°7′8.64″N, 3°27′7.40″W. (c and f) Schematic
tectonostratigraphic columns representing the current structural position of units and metamorphic geochronometers in the Nevado-Filábride Complex. CAMP stands
for Central Atlantic Magmatic Province. (d and e) Outcrop picture of thrust sheet in Sierra de los Filabres and Sierra Nevada with stereonets representing foliation
planes. Red lines indicate thrust relationships, while blue lines indicate no jump in their MDAs.

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
19 of 33
age for metamorphism of the NFC has been widely reported in numerous studies; however, Eocene metamor-
phism remains controversial. This marks the first study to propose a polyphase metamorphic evolution for the
NFC from multiple geochronometers and consistently resolve the multistage Cenozoic evolution of the region.
4.3.1. Eocene Metamorphism
An Eocene HP/Low-Temperature (HP/LT) metamorphic phase in the NFC has been suggested based on
40Ar/
39Ar
analyses (Augier, Agard, etal.,2005; Augier, Jolivet, & Robin,2005; Monié etal.,1991; Porkoláb etal.,2022),
while other studies have disregarded these data and attributed them to excess Ar because they do not fit evidence
for younger Miocene metamorphic ages interpreted as a HP/LT event (Behr & Platt,2012, de Jong,2003; De
Jong etal.,2001; Kirchner etal.,2016; Platt etal.,2006). However, B. Li and Massonne(2018) identified Eocene
monazite ages in the Mulhacén succession of the Sierra Nevada that support the Eocene
40Ar/
39Ar data and
suggest that the subduction of the NFC must have occurred prior to the Miocene metamorphic event. This was
corroborated by Aerden etal.(2022), who reported a late Eocene garnet Sm-Nd age (∼35Ma).
This study presents robust apatite and zircon overgrowth U-Pb ages that document a well-defined Eocene/Pale-
ocene metamorphic event between ∼60 and 35Ma (Figures2, 5a, 5b, 5e, and5f). On the basis of these data,
we suggest that this event represents a metamorphic event with temperatures that exceeded ∼450°C in the Betic
subduction zone. The Eocene metamorphic event is also recorded by apatite groups 2 and 4 (Figure2). Zircon
rims are observed at the upper parts of the structural column within the Mulhacén succession and the uppermost
Veleta unit. In most cases, zircon rims are euhedral while still following the oscillatory zoning of their cores
(Figure3a) and have Th/U ratios consistently less than 0.1, which argues for their metamorphic nature (Figure
S6 in Supporting InformationS1; e.g., Rubatto,2002; Williams,2001). With our depth-profiling techniques,
we were able to analyze the very thin rims (∼5μm) and recover a metamorphic population that previous studies
overlooked. Eocene rims are not observed throughout most of the Veleta unit and, in some cases, on samples from
the hanging wall of the thrust faults (Figure1), which confirms their subduction-related genesis and supports
differential metamorphic conditions across imbrication thrusts and argues for a post-Eocene age of fault activity.
Eocene apatite grains from Bédar-Macael orthogneisses (Group 2) exhibit bright cores and dark rims (Figures5a
and5b). Our apatite U-Pb depth-profiling data and the 2D apatite U-Pb mapping indicate that these bright core
zones correspond to high U concentrations (Figures3d and 3e). Previous studies have shown that recrystal-
lized apatite rims have significantly lower U concentrations than their cores (Henrichs etal., 2018; O'Sullivan
et al., 2020), which is in agreement with our 2D maps. Given the high U cores, we are confident that the
Eocene ages correspond to the core of the grains, and hence the original magmatic apatite cores must have been
completely reset. Due to the low U concentration and high common Pb composition of the rims, we are unable
to obtain a robust U-Pb age, but their formation must postdate the Eocene metamorphism. These samples also
contain quartz ameboid structures with grain boundary migration and feldspar crystals with evidence of bulging.
Together, the microstructural observations and apatite ages indicate that these rocks exceeded ∼450°C during
subduction metamorphism, which agrees with previously published P/T estimates (Augier, Agard, etal.,2005;
Augier, Jolivet, & Robin,2005; Booth-Rea etal.,2015; Ruiz-Cruz etal.,2015).
Apatite grains in Group 4 from Sierra de los Filabres and Sierra Alhamilla show a large dispersion of ages in the
Tera-Wasserburg space with lower-intercept ages ranging from Carboniferous to Eocene (Figures5e and5f). We
interpret this age dispersion as resulting from partially recrystallized apatite, where some zones of the crystal
lattice preserve the Eocene metamorphic event. Similar patterns of partially recrystallized apatite have been
observed in mylonitic zones in the Pyrenees (Odlum & Stockli,2020; Odlum etal.,2022), and the youngest ages
have been thought to record the most recent deformation event. Thin sections from our samples show evidence
of fluid-rock interactions with feldspar replacement by sericite (Figure6i). Because apatite grains from Sierra
Nevada are fully reset, the partially recrystallized apatite from Sierra de los Filabres and Sierra Alhamilla might
indicate that these rocks experienced lower peak temperatures. Similar temperature variations between the Betic
orogens have been previously observed in both the NFC and Alpujárride with higher temperatures in the west and
lower in the eastern domains (Bessière etal.,2022; Bessière, Augier, etal.,2021; Bessière, Jolivet, etal.,2021;
Platt et al., 2006). Additionally, different P/T conditions have also been observed among units in the same
localities, which results in a discrepancy among P/T work done in the area as compiled by Santamaría-López
etal.(2019).

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
20 of 33
Our new data unequivocally show strong evidence for an Eocene metamorphic event and are coeval with Eocene
metamorphic ages found by previous studies. Collectively, the textures we observe in apatite and zircon rims,
the closure temperature of apatite at ∼450°C, and the general absence of zircon rims in the structurally deepest
Veleta unit and across the thrust contacts confirm that metamorphism is subduction-related and not formed prior
to underthrusting. Augier, Jolivet, and Robin(2005) performed a detailed P-T study from syn-kinematic white-
mica ages that conclusively showed that HP conditions existed throughout the Eocene. Therefore, it is most likely
that the growth of our zircon rims and resetting of apatite grains can be attributed to HP metamorphic conditions
during the Eocene, although additional geochemical and in situ data in HP assemblages are needed to holistically
evaluate the nature of Eocene metamorphism.
4.3.2. Miocene Metamorphism
The Miocene metamorphic event has been well documented in the NFC and has been generally interpreted as
an HP/LT metamorphic event with age constraints spanning from ∼20 to 13Ma (Gómez-Pugnaire etal.,2012;
Lopez Sanchez-Viscaino etal., 2001; Platt et al., 2006). We find a distinct Miocene zircon rim population
spanning ∼30-10Ma, in good agreement with ages from previous studies. The Miocene zircon metamorphic
overgrowths show a different morphology than the Eocene ones, with porous structures and thick, uneven rims
around the cores of the zircon that suggest a metasomatic nature for these rims (Figures3b and3c) (e.g., Poulaki
etal.,2021). The majority of samples with Miocene zircon rims also have Eocene zircon rims and are found only
in the upper structural levels of the NFC. The two samples that yielded Eocene core apatite ages (Group 2) also
yielded Miocene zircon rims (Figures5a and5b). Hence, it is possible that the Group 2 apatite rims from these
grains are Miocene in age and coeval with zircon rim formation, but we were not able to obtain an age due to the
high common lead composition and low U concentrations (Figures3d and3e).
Additionally, we found Miocene (∼15Ma) apatite ages (Group 3) in the Mulhacén succession in the Sierra
Nevada (Figures5c and5d). These grains have complicated internal textures with multiple mixed zones of bright
rims and patchy cores (Figure5d and Figure S2 in Supporting InformationS1). Even though we depth-profiled
these grains, the complicated internal structure does not allow us to clearly differentiate if the rim or core of the
apatite corresponds to the Miocene age we obtain; nevertheless, the cores must be reset in the Miocene since we
do not observe a dispersive age spectrum as seen in Group 4. Microstructures from this sample (19SSN11) show
a strong maximum in the center, but a large opening angle, and feldspar does not show recrystallization, possibly
indicating lower temperatures (Figures7f and7g). Another sample with Miocene apatite contains garnet, and
the quartz grains are elongated and exhibit grain boundary migration and feldspar recrystallization (Figures7h
and7i). The recrystallization of feldspar with subgrains and subgrain rotation are indicators of temperatures at
∼550°C. However, the ages of apatite do not necessarily record the precise timing and magnitude of these temper-
atures since apatite could reset under lower temperatures (∼450°C) and be influenced by the presence of fluids
that these rocks experienced during Early Miocene reheating and rapid exhumation. Hence, recrystallization of
apatite might have occurred at lower temperatures and postdate the recrystallization of feldspar grains.
Metamorphism in the NFC during the Miocene is complex, and more recent studies have challenged the classic
HP/LT interpretation of this event. Various scenarios include stages of late reheating (Bakker etal.,1989; Booth-
Rea etal., 2015; B. Li & Massonne, 2018; Vissers etal., 1995), decompression (Augier, Agard, etal.,2005;
Augier, Jolivet, & Robin,2005; Ruiz-Cruz etal.,2015), and/or fluid involvement that contributed to new mineral
growth such as apatite, zircon, and garnet. This reheating stage might also be the reason for the confusion in the
literature regarding the nature of Miocene metamorphism and whether it reflects an HP/LT or HT/LP event. Stud-
ies dating garnet argue for HP/LT metamorphism in the Miocene (e.g., Kirchner etal.,2016; Platt etal.,2006).
If the Eocene metamorphic event also represents HP/LT metamorphism, that could possibly indicate diachronous
metamorphism of the NFC units, with peak metamorphism experienced at different times. Our data show strong
evidence for metasomatic apatite and zircon formation during the Late Miocene (∼15 Ma). These ages are
slightly younger than the Early Miocene ages attributed to HP/LT metamorphism by previous studies (Kirchner
etal.,2016; Platt etal.,2006). Therefore, we suggest that our Miocene chronometers may record both HP/LT
peak metamorphic conditions in the Early Miocene followed by reheating and fluid-rich metamorphism coeval
with exhumation in the Late Miocene. Previous work has identified at least five stages of fluid pulses starting
in the Miocene, with the initial pulse corresponding to metamorphic fluids related to reheating and dehydration
reactions (Dyja etal.,2016). The involvement of fluid pulses in the Late Miocene suggests that the NFC was struc-
turally positioned above a dehydrating slab and actively exhumed in the overriding plate at this time. The spatial
distribution of observed Miocene metamorphism only in the upper unit may indicate that fluid-rock interactions

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
21 of 33
were preferentially localized along the upper units where the weak strata initially deformed by thrust faulting
and later reactivated as extensional shear zones may have facilitated fluid flow (Martínez-Martínez etal.,2010;
Porkoláb etal.,2022). The distribution of new metamorphic ages found in our study also aligned well with previ-
ous descriptions of the metamorphic history and structural mapping by Martínez-Martínez etal.(2010).
4.4. Reconciling Temperature Estimates and Chronological Constraints
The majority of the Veleta unit does not show any MDA duplications and has consistent foliation fabrics, argu-
ing against widespread structural imbrication. Microstructural analyses show minor subgrains with no quartz LPO
or feldspar deformation, indicating either static recrystallization or pressure solution mechanisms (Passchier &
Trouw,2005; Rutter,1983; Stöckhert,2002). Studies from the exhumed Arosa zone in the Alps have shown that pres-
sure solution is dominant under temperatures less than ∼400°C (Condit etal.,2022). These microstructures, combined
with pre-Cenozoic apatite U-Pb ages, suggest that the majority of Veleta experienced lower temperatures than the
rest of the NFC, likely less than ∼450°C. In contrast, MDAs and petrological relationships indicate older-on-younger
relationships at the upper structural parts of the NFC, including the Mulhacén succession and the uppermost Veleta
unit. At these structurally higher levels, we observed Cenozoic metamorphic zircon rims and Cenozoic apatite grains
(Figures1, 8c, and8f). In the upper section of the Veleta unit, a higher degree of metamorphism is evidenced by
the appearance of garnets, intracrystalline plasticity in quartz and feldspar, and reset Cenozoic apatite ages. The
Mulhacén succession likely recorded the highest overall temperatures among the NFC inferred by intracrystalline
plasticity in both quartz and feldspar grains, with higher temperatures in Tahal exhibiting dynamic recrystallization in
feldspar and lower temperatures in the Bédar-Macael with bulging in feldspar grains. In Sierra Nevada, these upper
units exceeded ∼550°C with reset apatite, grain boundary migration in quartz, and recrystallization of feldspar grains.
Previous studies observed this apparent upward increase in the metamorphic record and attributed it to an
inverted thermal gradient in the Betic subduction zone. Specifically, Behr and Platt(2013) argue that the upper
parts of Veleta unit experienced deformation with pressure solution creep under relatively lower temperatures of
490–530°C (Behr & Platt,2012), while the Mulhacén succession deformed at higher temperatures under dislo-
cation creep locally up to 623±68°C (Behr & Platt,2012). Santamaría-López etal.(2019) demonstrated the
similarity of P/T paths among the different NFC units with higher temperatures at the upper parts and also argued
for an inverted thermal gradient rather than tectonic relationships between the units. Another scenario proposed
that overheating occurred during this time due to contact from the overriding hot Alpujárride complex, causing
heat and fluid transfer (Aerden etal.,2013; Bakker etal.,1989). We suggest that differences in the temperatures
and deformation mechanisms are instead best explained by variations in the peak subduction depths throughout
the NFC. This interpretation is supported by thermal grading from fully reset apatite in the West to partially reset
apatite grains in the East within the same level of the Mulhacén Succession along the strike.
The Carboniferous and Jurassic metamorphic ages of the Veleta unit reveal that it has previously experienced meta-
morphism and hence dehydration prior to entering the subduction system. Additionally, the apparent unconformities
with missing Permian strata and overall thicker stratigraphic sequence in the Veleta unit could indicate that it was
deposited in a more proximal domain to the Variscan Orogeny and Pangea rifting events than the overlying NFC
units (Poulaki & Stockli,2022) despite subsequent minor thinning due to extension and detachment faulting during
the latest Miocene. These conditions would result in a more buoyant succession that would provide resistance to
deep subduction. Accordingly, previous work estimated pressures in the Veleta unit 2–8kbar lower than the overlay-
ing Mulhacén succession (Booth-Rea etal.,2015; B. Li & Massonne,2018). Our data argue that the lower Veleta
basement could not have exceeded ∼450°C during subduction since apatite grains do not record any Cenozoic meta-
morphism. Collectively, we propose that the monotonous Veleta unit acted as a thick and homogeneous basement
suite during the subduction of the NFC. The buoyant nature of Veleta may have provided a mechanism to trigger
underplating of the NFC units and transfer to the overriding plate of the Iberian margin.
4.5. Regional Implications for the Betic Subduction Zone
The debate regarding the initiation and polarity of subduction in the Western Mediterranean derives from the compli-
cated plate tectonic configuration of the region. Many studies either propose southeast-dipping subduction followed by
reversal and northwest dipping subduction (Frizon de Lamotte etal.,2000; Rehault etal.,1984), a south-east dipping
subduction (Behr & Platt,2013) or generally a north-northwest dipping subduction zone (e.g., Bezada etal.,2013;
Booth-Rea etal.,2007; Brun & Faccenna,2008; Carminati etal.,2012; Chertova etal.,2014; Faccenna etal.,2004;

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
22 of 33
Rosenbaum etal.,2002; van Hinsbergen etal.,2020). Geochronologic constraints on the Cenozoic evolution of the
Alpujárride complex suggest that it has experienced at least two metamorphic events. The first HP/LT metamorphic
event is evidenced by the presence of carpholite, kyanite, chloritoid, and aragonite (Azañón & Crespo-Blanc,2000;
Booth-Rea etal.,2002,2005). Pressure and temperature estimates yield 400±100°C and 1±0.2GPa (Azañón &
Crespo-Blanc,2000; Platt etal.,2013) with an estimated timing of Eocene (e.g., Bessière etal.,2022; Bessière, Augier,
etal.,2021; Bessière, Jolivet, etal.,2021; Marrone etal.,2021; Monié etal.,1991; Platt etal.,2005). After the HP/
LT event, fine-grained Permo-Triassic schists of the Alpujárride may have experienced 400°C and 0.3–0.4GPa in the
Miocene (Azañón & Crespo-Blanc,2000; Bakker etal.,1989; Monié etal.,1991; Platt etal.,2005). Even though the
P/T conditions of Alpujárride and the NFC are different, the timing of the metamorphic events is similar (Bessière
etal., 2022; Bessière, Augier, et al., 2021; Bessière, Jolivet, etal.,2021). Additionally, Poulaki & Stockli(2022)
showed that the NFC and Alpujárride have nearly identical sedimentary provenance signatures and were likely depos-
ited nearby in similar tectonic settings, showing a close affinity between the Internal Betic terranes.
The similarity in provenance data between NFC and Alpujárride suggests that these units may have been laterally
continuous throughout their depositional history but experienced different levels of Cenozoic metamorphism.
These differences can be explained by the subduction of the NFC to greater depths beneath the Iberian margin
than the Alpujárride Complex. In this study, the new age constraints from the NFC indicate that Alpujárride and
the NFC were subducted at similar times. Since Alpujárride is currently on the hanging wall of low-angle normal
faults, Alpujárride must have been subducted first, followed by the NFC in a lateral continuation of the same
subduction system as recently described by several studies (Aerden etal.,2022; Porkoláb etal.,2022; Poulaki &
Stockli,2022). Previous models suggest that the subduction of the NFC occurs much later in the Miocene (e.g.,
Van Hinsbergen etal.,2020); however, our data, along with recently published data (Aerden etal.,2022; B. Li
& Massonne,2018; Porkoláb etal.,2022), suggests that the subduction of the NFC is likely to have commenced
around the Early Eocene (Figure9). New precise metamorphic ages in this study show that the Betic subduction
Figure 9. Compilation of ages from the Nevado-Filábride Complex with focus on the metamorphic ages during Cenozoic
subduction. Symbols highlighted by the red outline are from this study. Garnet Lu/Hf: Platt etal.(2006); Monazite U-Pb: B.
Li and Massonne(2018); Allanite: Santamaría-López etal.(2019); Ar/Ar: Augier Agard, etal.(2005) and Augier, Jolivet,
and Robin(2005); Rb-Sr Garnet: Kirchner etal.(2016); Zircon U-Pb; Gómez-Pugnaire etal.(2012); Garnet Sm-Nd: Aerden
etal.(2022); Porkoláb etal.(2022).

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
23 of 33
zone initiated at least since the Eocene and progressively subducted and underplated units of the NFC. Our zircon
rim age constraints on the timing of subduction zone metamorphism give an approximate timing of initial under-
thrusting around ∼60Ma, which reconciles the controversy regarding subduction initiation and the large range of
metamorphic ages spanning from Eocene to Miocene.
5. Implications
5.1. The Significance of Presubduction Architecture for Subduction Underplating
5.1.1. The Buoyancy of the Crystalline Basement (Veleta)
Geochronological data, combined with the MDAs along other transects, indicate that the Veleta unit did not form
any large duplications or repetitions during subduction or exhumation and has also experienced metamorphism
prior to subduction. We suggest that the Veleta unit behaves as a thick buoyant basement during the subduction
of the NFC due to its large thickness and its prior dehydration from multiple previous metamorphic events
during the Variscan orogeny and subsequent Jurassic rifting (Figure 10b). Prior metamorphism significantly
contributes to the homogenization of the unit and may anneal some of the previous stratigraphic weaknesses. We
envision that the metamorphic Veleta basement would behave more as a strong and coherent continental crustal
block compared to unmetamorphosed sedimentary rocks. Additionally, even though some lithologies similar to
the Veleta appear in the higher units, their intercalation with various lithologies such as metabasites and serpen-
tinites result in weak and negatively buoyancy pockets that differ from the homogenous thick and continuous
Veleta sequence.
Despite being subducted in the Cenozoic, our thermochronometers coupled with microstructures suggest that
the Veleta basement did not exceed ∼450°C, which contradicts previous P/T estimates. Similar controversies are
present in the Alps, where garnet and zircon ages are ∼320–340Ma (Liati etal.,2009; Sandmann etal.,2014)
and preserve Variscan metamorphism rather than later Alpine Orogeny metamorphism. This discrepancy merits
a reevaluation of P/T estimates based on various methods or further investigation into the conditions under which
minerals grow and reset their thermo-chronometer clocks during metamorphic events.
5.1.2. The Imbrication of the Sedimentary/Igneous Cover (Mulhacén Succession)
The Mulhacén succession forms a Permian to Mesozoic syn- and postrift sedimentary/igneous package with
heterogeneous lithologies, including mostly metasedimentary rocks in addition to orthogneisses, metabasic rocks,
marble and ultramafic slivers (Figure10a; e.g., Poulaki & Stockli,2022; Puga etal.,2005; Menzel etal.,2019).
During Cenozoic subduction, the Mulhacén succession was cut by a series of imbricate thrust sheets and expe-
rienced significantly higher temperatures during HP/LT metamorphism than the underlying Veleta basement
unit. In contrast to the monotonous Veleta basement, the heterogeneous architecture with varying lithologies
in the Mulhacén succession may have contained presubduction inherited faults or a mechanical stratigraphy
that allowed for the localization of strain and formation of imbricate thrusts to stack tectonic slivers decoupled
from the intact basement. Additionally, as has been shown in other subduction zones, underplating of sediments
is largely facilitated by the involvement of lithological heterogeneities (Tewksbury-Christle etal.,2021). Even
though some of the lithologies in the Mulhacén succession are similar to Veleta, the rheological layering likely
assists the development of large thrust faults, which also lead to different P/T conditions. This scenario would be
similar to basement-detached imbrication during fold-thrust belt development (Pfiffner,2016). Since Veleta and
Mulhacén indeed have somewhat similar lithologies, we conclude that the primary factors controlling the differ-
ent structural styles are the unit thickness, metamorphic history, and presubduction architecture.
These findings have important implications for dynamics within subduction systems since the basement plays an
important role in the forces that drive and resist subduction, as well as the exhumation processes. As previously
proposed for the Western Mediterranean, the main driver of exhumation for the Betic subduction complex is slab
rollback (e.g., Brun & Faccenna,2008; Gautier etal.,1999; Jolivet etal.,2003) with the contribution of buoyant
continental crust and the basement rocks that today represent graphitic mica schist at cores of elongated exten-
sional domes. The involvement of thick and buoyant basement rocks in the Mediterranean is one of the major
drivers of underplating (Agard etal.,2009,2018; Jolivet etal.,2005) and contributes to the mass transfer and
recycling of older continental crust (Doin & Henry,2001).

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
24 of 33
Figure 10.

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
25 of 33
5.2. Subduction Zone Coherent Underplating
Underplating along the deep subduction interface has been imaged by geophysical studies along conver-
gent margins such as Chile, North-West America, Alaska, Japan, and New Zealand, as summarized by
Scholl(2021). All these studies imaged underplating at depths of ∼20–30km, but due to limitations of the
methods, crucial information is missing from the deeper underplating zone down to ∼60km depth where
we know these rocks experienced metamorphism before returning back to the surface. At shallower depths,
underplating may be initiated as the decollement steps down and accretes slivers to the base of the overriding
plate (e.g., Bangs etal.,2020). Furthermore, the involvement of elevated topography may provide physical
mechanisms or enhanced vertical buoyancy forces to detach crust and sediments from the sinking slab (e.g.,
Cloos,1993). Work by Piana Agostinetti and Faccenna(2018) shows imbrication and underplating occur-
ring at the Adriatic continental convergent zone at about 40km depth using active seismic data and receiver
function analysis. In this study, we were able to identify contacts that represent fossil thrust imbricate faults
that accommodate underplating and shed light on the nature of these contacts (Figures10b and10c). Seis-
mic reflection data have also shown that the plate boundary often changes from a single bright reflection at
shallow depths to a wide package of bright reflectivity, which may indicate underplating at greater depths
(e.g., J. Li etal.,2015).
Our systematic high-density sampling and petrographic observations from the NFC show continuous strati-
graphic successions and multiple older-on-younger relationships at the structurally higher levels. Although the
formation of metamorphic zircon rims depends on many factors such as mineral budget and fluid composition,
we can assess general trends in their presence or absence from our structural column to infer the metamorphic
conditions and timing of imbrication. The absence of Eocene zircon rims in several samples from the hanging
wall and different apatite ages across the thrust faults suggests that stacking and underplating began during or
after peak metamorphism and continues while these rocks are in the exhumation path (Figure10b). The timing
of their formation is also supported by the recent study by Porkoláb etal.(2022), where in situ Ar/Ar analyses
suggest that imbrication occurs after peak metamorphism with contraction continuing until the units pass through
the brittle-ductile transition (Behr and Platt,2012; Booth-Rea etal.,2005,2015). This is further supported by the
large distribution of temperatures that have been revealed from various studies for the NFC as recently compiled
by Santamaría-López etal. (2019). The overall higher temperatures in the upper NFC have also been previ-
ously observed for these units (Behr & Platt,2012; Santamaría-López etal.,2019). These studies proposed an
inverted metamorphic gradient; however, the lower pressures in Veleta than in the Mulhacén succession (Booth-
Rea etal., 2015; Menzel et al., 2019), as well as the different metamorphic conditions between these units,
instead argue that these observations can be reconciled by different maximum depths of subduction (Figure10).
In this scenario, the Mulhacén succession would be subducted first and reach peak metamorphic conditions
starting in the Eocene and prolonged until the Early Miocene. The heterogeneous layering of lithologies within
the Mulhacén succession allowed for the localization of strain and formation of imbricate thrust sheets around
peak metamorphic conditions near the decoupling depth. These thrust sheets continued to develop during exhu-
mation as they were subsequently stacked onto the trailing Veleta unit at shallower depths in the Late Miocene.
Together, the culmination of a thick, buoyant package drove underplating of the fused Veleta and Mulhacén
succession to the overriding plate (Figure10b). These processes may have varied slightly between ranges in
the Betic Cordillera due to different depths of NFC decoupling indicated by the partially recrystallized apatite
in Sierra de los Filabres and Sierra Alhamilla suggesting that they experienced lower temperatures than Sierra
Nevada (Figures5e and5f).
While underplating is often thought to involve the formation of mélange zones and chaotic mixtures (Cloos
& Shreve,1988; Shreve & Cloos,1986), we present concrete evidence for coherent underplating of imbricate
stacks of tectonic slivers thrusted on top of each other. In many cases, the base of these thrusts is characterized by
orthogneiss slivers. The differences in material rheologies might be due to the weak decoupling horizons where
Figure 10. Tectono-metamorphic evolution of the Nevado-Filábride Complex (NFC) from subduction to subsequent exhumation. (a) Presubduction configuration
of the NFC (modified from Poulaki and Stockli(2022)) illustrates the units' succession from Devonian to Early Jurassic. (b) Subduction schematic during the Eocene
high-pressure (HP)/LT metamorphism. The Veleta unit acts as a buoyant basement resisting subduction, while the sedimentary Mulhacén strata reach greater depths and
are underplated, forming imbricate thrusts. Insets of Apatite and zircon CL images formed during the Eocene HP/LT metamorphism and their relative position on the
subduction interface. (c) Subduction schematic during Miocene exhumation. The NFC is partially exhumed during this phase and reheated, metamorphism is continuing
with strong effects of fluids, as indicated by the apatite and zircon textures.

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
26 of 33
fault formation occurs. Similar coherent structures have been observed in the Cyclades (Kotowski etal.,2022;
Poulaki etal.,2019; Seman,2016) and on Syros with mixed brittle-ductile deformation where brittle blueschist
veins are coeval with ductile shearing (Kotowski & Behr,2019; Kotowski etal.,2022). Underplating of the NFC
likely occurred around peak metamorphic conditions at ∼40–60km depth, approximately where the slab reaches
the Moho depth of the overlying Iberian plate. Duplex structures like the ones we documented here have been
imaged in active subduction zones (Calvert etal.,2011; Henrys etal.,2013; Moore etal.,1991) but are also
predicted to occur during the underplating process by geodynamic models (e.g., Menant etal.,2019). In contrast
to this coherent manner of underplating, subduction zones dominated by pelagic sediments atop oceanic crust
can potentially form a chaotic mélange during underplating (e.g., Angiboust etal.,2013; Cloos & Shreve,1988).
However, recent work by Harvey etal.(2021) shows decoupling and coherent underplating beneath a mélange
zone by juxtaposition with the amphibolite domain of the slab, suggesting that even in mélange-like underplating,
mixing may occur in a more systematic manner than previously thought. Many studies have shown that slabs
often stall and stagnate at the mantle transition zone as a possible mechanism for rollback and trench retreat
(e.g., Agrusta etal.,2017; Billen,2010; Marquardt & Miyagi,2015; Torii & Yoshioka,2007). Therefore, if the
Betic slab could not easily penetrate into the lower mantle, this could be a mechanism for triggering slab rollback
during Miocene, underplating of the NFC, and the massive trench migration toward the West as has been docu-
mented by various studies (e.g., Brun & Faccenna,2008; Faccenna etal.,2004).
The presence of Miocene apatite and zircon ages with metasomatic morphologies located only within the upper
NFC records metamorphism under the presence of abundant fluids. Hence, the previously formed thrust faults are
not only potential zones of localized strain but also act as weak zones during the exhumation processes and path-
ways for fluids during various fluid pulses that have been identified in the upper units of the NFC (Figure10c;
Dyja etal.,2016). Additionally, Late Miocene extensional shear zones along the NFC units have been previously
proposed by various authors, and the thrust faults identified in this study would be ideal inherited weak zones for
subsequent reactivation during unroofing (Martínez-Martínez etal.,2002,2010; Porkoláb etal.,2022). Rapid
rollback and trench migration could potentially facilitate slab tearing and give rise to the reheating, abundant fluid
percolation, and punctuated arc magma genesis observed in the Late Miocene. Similar polyphase metamorphic
relationships have been observed in other tectonic settings in the western United States (Constenius etal.,2003)
as well as in Cyclades, Greece (Poulaki etal.,2019,2021).
6. Conclusions
In this study, zircon and apatite geo/thermochronology coupled with microstructural and field observations
provide unprecedented details on the underplated subduction complex in Southern Spain. Within the NFC,
we identify at least two phases of subduction zone metamorphism in the Eocene and Miocene as well as an
increase in the metamorphic grade from the lower to upper units. Our findings indicate that subduction must
have initiated at least since ∼60Ma, which is significantly earlier than previous models. The polyphase meta-
morphic history of the NFC includes diachronous HP/LT peak metamorphic conditions in the Eocene and
Early Miocene, followed by reheating and fluid-driven metasomatism during underplating and exhumation
in the Late Miocene.
This work highlights the importance of the presubduction architecture for structural styles of deformation
during underthrusting and underplating. The Veleta basement of the NFC had already experienced metamor-
phism during the Variscan orogeny and Jurassic rifting prior to subduction. Upon entering the subduction
system, it behaved as a thick, buoyant block that resisted deep subduction and acted as an internal force
mechanism to assist underplating and transfer to the overriding plate. In contrast, the structurally higher
Mulhacén succession of the NFC formed coherent slivers with imbricate thrusts coeval with peak meta-
morphism above 500°C. Sedimentary protoliths and stratigraphic layering play an important role in where
deformation becomes localized within thicker shear zones (∼100s m) and strain localization of thrust faults,
which appear to preferentially develop along the boundary of more buoyant lithologies, such as slivers of
orthogneisses. Decoupling of subducted materials from the downgoing slab occurs during or after peak
metamorphism. For the Betic subduction zone, density contrasts between metamorphosed sediments and the
overriding mantle wedge, the trailing subduction of a buoyant coherent block, and slab stagnation near the
mantle transition zone may have been contributing factors to underplating the NFC, transitioning to exhu-
mation, and trench migration to its current position at the Gibraltar Arc.

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
27 of 33
Data Availability Statement
All of the data are publicly available at https://doi.org/10.5281/zenodo.7644485. All the geochronology data can
also be found at www.geochron.org.
References
Aerden, D. G. A. M., Bell, T. H., Puga, E., Sayab, M., Lozano, J. A., & de Federico, A. D. (2013). Multi-stage mountain building vs. relative plate
motions in the Betic Cordillera deduced from integrated microstructural and petrological analysis of porphyroblast inclusion trails. Tectono-
physics, 587, 188–206. https://doi.org/10.1016/j.tecto.2012.11.025
Aerden, D. G. A. M., Farrell, T. P., Baxter, E. F., Stewart, E. M., Ruiz-Fuentes, A., & Bouybaouene, M. (2022). Refined tectonic evolution
of the Betic-Rif orogen through integrated 3-D microstructural analysis and Sm-Nd dating of garnet porphyroblasts. Tectonics, 41(10),
e2022TC007366. https://doi.org/10.1029/2022tc007366
Agard, P., Plunder, A., Angiboust, S., Bonnet, G., & Ruh, J. (2018). The subduction plate interface: Rock record and mechanical coupling (from
long to short timescales). Lithos, 320, 537566–566. https://doi.org/10.1016/j.lithos.2018.09.029
Agard, P., Yamato, P., Jolivet, L., & Burov, E. (2009). Exhumation of oceanic blueschists and eclogites in subduction zones: Timing and mecha-
nisms. Earth-Science Reviews, 92(1–2), 53–79. https://doi.org/10.1016/j.earscirev.2008.11.002
Agrusta, R., Goes, S., & Van Hunen, J. (2017). Subducting-slab transition-zone interaction: Stagnation, penetration and mode switches. Earth and
Planetary Science Letters, 464, 10–23. https://doi.org/10.1016/j.epsl.2017.02.005
Angiboust, S., Agard, P., De Hoog, J. C. M., Omrani, J., & Plunder, A. (2013). Insights on deep, accretionary subduction processes from the Sistan
ophiolitic “mélange” (Eastern Iran). Lithos, 156, 139–158. https://doi.org/10.1016/j.lithos.2012.11.007
Arend Zevenhuizen, W. (1989). Quartz fabrics and recumbent folds in the Sierra de Los Filabres (SE-Spain). Geodinamica Acta, 3(1), 95–105.
https://doi.org/10.1080/09853111.1989.11105177
Asti, R., Lagabrielle, Y., Fourcade, S., Corre, B., & Monié, P. (2019). How do continents deform during mantle exhumation? Insights from the
northern Iberia inverted paleopassive margin, western Pyrenees (France). Tectonics, 38(5), 1666–1693. https://doi.org/10.1029/2018tc005428
Augier, R., Agard, P., Monié, P., Jolivet, L., Robin, C., & Booth-Rea, G. (2005). Exhumation, doming and slab retreat in the Betic Cordillera
(SE Spain): In situ
40Ar/
39Ar ages and P–T–d–t paths for the Nevado-Filabride Complex. Journal of Metamorphic Geology, 23(5), 357–381.
https://doi.org/10.1111/j.1525-1314.2005.00581.x
Augier, R., Jolivet, L., & Robin, C. (2005). Late orogenic doming in the eastern Betic Cordilleras: Final exhumation of the Nevado-Filabride
complex and its relation to basin genesis. Tectonics, 24(4), TC4003. https://doi.org/10.1029/2004tc001687
Azañón, J. M., & Crespo-Blanc, A. (2000). Exhumation during a continental collision inferred from the tectonometamorphic evolution of the
Alpujárride Complex in the central Betics (Alboran Domain, SE Spain). Tectonics, 19(3), 549–565. https://doi.org/10.1029/2000tc900005
Azañón, J. M., Galve, J. P., Pérez-Peña, J. V., Giaconia, F., Carvajal, R., Booth-Rea, G., etal. (2015). Relief and drainage evolution during the
exhumation of the Sierra Nevada (SE Spain): Is denudation keeping pace with uplift? Tectonophysics, 663, 19–32. https://doi.org/10.1016/j.
tecto.2015.06.015
Bachmann, F., Hielscher, R., & Schaeben, H. (2010). Texture analysis with MTEX–free and open source software toolbox. In Solid state phenom-
ena (Vol. 160,pp.63–68). Trans Tech Publications Ltd.
Bakker, H. E., Jong, K. D., Helmers, H., & Biermann, C. (1989). The geodynamic evolution of the Internal Zone of the Betic Cordilleras (south-
east Spain): A model based on structural analysis and geothermobarometry. Journal of Metamorphic Geology, 7(3), 359–381. https://doi.
org/10.1111/j.1525-1314.1989.tb00603.x
Balanyá, J. C., & García-Dueñas, V. (1987). Les directions structurales dans le Domaine d'Alborán de part et d'autre du Détroit de Gibraltar.
Comptes rendus de l'Académie des sciences. Série 2, Mécanique, Physique, Chimie, Sciences de l'univers, Sciences de la Terre, 304(15),
929932.
Balanyá, J. C., García-Dueñas, V., Azañón, J. M., & Sánchez-Gómez, M. (1997). Alternating contractional and extensional events in the Alpujar-
ride nappes of the Alboran Domain (Betics, Gibraltar Arc). Tectonics, 16(2), 226–238. https://doi.org/10.1029/96tc03871
Bangs, N. L., Morgan, J. K., Tréhu, A. M., Contreras-Reyes, E., Arnulf, A. F., Han, S., etal. (2020). Basal accretion along the south central
Chilean margin and its relationship to great earthquakes. Journal of Geophysical Research: Solid Earth, 125(11), e2020JB019861. https://doi.
org/10.1029/2020jb019861
Behr, W. M., & Bürgmann, R. (2021). What’s down there? The structures, materials and environment of deep-seated slow slip and tremor. Phil-
osophical Transactions of the Royal Society A, 379(2193), 20200218. https://doi.org/10.1098/rsta.2020.0218
Behr, W. M., & Platt, J. P. (2012). Kinematic and thermal evolution during two-stage exhumation of a Mediterranean subduction complex. Tecton-
ics, 31(4). https://doi.org/10.1029/2012tc003121
Behr, W. M., & Platt, J. P. (2013). Rheological evolution of a Mediterranean subduction complex. Journal of Structural Geology, 54, 136–155.
https://doi.org/10.1016/j.jsg.2013.07.012
Bessière, E., Augier, R., Jolivet, L., Précigout, J., & Romagny, A. (2021). Exhumation of the Ronda peridotite during hyper-extension: New
structural and thermal constraints from the Nieves Unit (western Betic Cordillera, Spain). Tectonics, 40(10), e2020TC006271. https://doi.
org/10.1029/2020tc006271
Bessière, E., Jolivet, L., Augier, R., Scaillet, S., Précigout, J., Azañon, J. M., etal. (2021). Lateral variations of pressure-temperature evolution in
non-cylindrical orogens and 3-D subduction dynamics: The Betic-Rif Cordillera example. BSGF-Earth Sciences Bulletin, 192(1), 8. https://
doi.org/10.1051/bsgf/2021007
Bessière, E., Scaillet, S., Augier, R., Jolivet, L., Miguel Azañón, J., Booth-Rea, G., etal. (2022).
40Ar/
39Ar age constraints on HP/LT meta-
morphism in extensively overprinted units: The example of the Alpujárride subduction complex (Betic Cordillera, Spain). Tectonics, 41(2),
e2021TC006889. https://doi.org/10.1029/2021TC006889
Bezada, M. J., Humphreys, E. D., Toomey, D. R., Harnafi, M., Dávila, J. M., & Gallart, J. (2013). Evidence for slab rollback in westernmost Medi-
terranean from improved upper mantle imaging. Earth and Planetary Science Letters, 368, 51–60. https://doi.org/10.1016/j.epsl.2013.02.024
Billen, M. I. (2010). Slab dynamics in the transition zone. Physics of the Earth and Planetary Interiors, 183(1–2), 296–308. https://doi.
org/10.1016/j.pepi.2010.05.005
Booth-Rea, G., Azañón, J. M., Goffé, B., Vidal, O., & Martínez-Martínez, J. M. (2002). High-pressure, low-temperature metamorphism in Alpu-
járride units of southeastern Betics (Spain). Comptes Rendus Geoscience, 334(11), 857–865. https://doi.org/10.1016/s1631-0713(02)01787-x
Booth-Rea, G., Azañón, J. M., Martínez-Martínez, J. M., Vidal, O., & García-Dueñas, V. (2005). Contrasting structural and P-T evolution of
tectonic units in the southeastern Betics: Key for understanding the exhumation of the Alboran Domain HP/LT crustal rocks (western Medi-
terranean). Tectonics, 24(2), TC2009. https://doi.org/10.1029/2004tc001640
Acknowledgments
This work was funded by GSA and UT
research grants (Poulaki), the Chevron
(Gulf) Centennial Endowment (Stockli),
and UTChron laboratory funds. We
would like to thank Lisa Stockli for her
assistance in the laboratory, Sharon
Mosher and Cailey Condit for their help
with the microstructures, Phil Orlandini
for his help with EBSD data collection,
and Sofia Laskari for her assistance in
the field. Many thanks to Mark Cloos,
Claudio Faccenna, Margo Odlum,
William Hoover, Romain Augier, and
Eloise Bessière for thoughtful discus-
sions. We thank John Platt and Guillermo
Booth-Rea for their constructive reviews
that greatly improved the manuscript, as
well as Whitney Behr for the editorial
handling.

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
28 of 33
Booth-Rea, G., Martínez-Martínez, J. M., & Giaconia, F. (2015). Continental subduction, intracrustal shortening, and coeval upper-crustal
extension: PT evolution of subducted south Iberian paleomargin metapelites (Betics, SE Spain). Tectonophysics, 663, 122–139. https://doi.
org/10.1016/j.tecto.2015.08.036
Booth-Rea, G., Ranero, C. R., & Grevemeyer, I. (2018). The Alboran volcanic-arc modulated the Messinian faunal exchange and salinity crisis.
Scientific Reports, 8(1), 1–14. https://doi.org/10.1038/s41598-018-31307-7
Booth-Rea, G., Ranero, C. R., Martínez-Martínez, J. M., & Grevemeyer, I. (2007). Crustal types and Tertiary tectonic evolution of the Alborán
sea, western Mediterranean. Geochemistry, Geophysics, Geosystems, 8(10), Q10005. https://doi.org/10.1029/2007gc001639
Brandon, M. T., Roden-Tice, M. K., & Garver, J. I. (1998). Late Cenozoic exhumation of the Cascadia accretionary wedge in
the Olympic Mountains, northwest Washington State. Geological Society of America Bulletin, 110(8), 985–1009. https://doi.
org/10.1130/0016-7606(1998)110<0985:lceotc>2.3.co;2
Brun, J. P., & Faccenna, C. (2008). Exhumation of high-pressure rocks driven by slab rollback. Earth and Planetary Science Letters, 272(1–2),
1–7. https://doi.org/10.1016/j.epsl.2008.02.038
Burov, E., Jolivet, L., Le Pourhiet, L., & Poliakov, A. (2001). A thermomechanical model of exhumation of high pressure (HP) and ultra-
high pressure (UHP) metamorphic rocks in Alpine-type collision belts. Tectonophysics, 342(1–2), 113–136. https://doi.org/10.1016/
s0040-1951(01)00158-5
Calvert, A. J., Preston, L. A., & Farahbod, A. M. (2011). Sedimentary underplating at the Cascadia mantle-wedge corner revealed by seismic
imaging. Nature Geoscience, 4(8), 545–548. https://doi.org/10.1038/ngeo1195
Capella, W., Spakman, W., van Hinsbergen, D. J., Chertova, M. V., & Krijgsman, W. (2020). Mantle resistance against Gibraltar slab dragging as
a key cause of the Messinian Salinity Crisis. Terra Nova, 32(2), 141–150. https://doi.org/10.1111/ter.12442
Carminati, E., Lustrino, M., & Doglioni, C. (2012). Geodynamic evolution of the central and western Mediterranean: Tectonics vs. igneous
petrology constraints. Tectonophysics, 579, 173–192. https://doi.org/10.1016/j.tecto.2012.01.026
Casalini, M., Tommasini, S., Guarnieri, L., Avanzinelli, R., Lanari, R., Mattei, M., & Conticelli, S. (2022). Subduction-related lamproitic signa-
ture in intraplate-like volcanic rocks: The case study of the Tallante alkali basalts, Betic Chain, South-Eastern Spain. Italian Journal of
Geosciences, 141(1), 144–159. https://doi.org/10.3301/ijg.2022.06
Chemenda, A. I., Mattauer, M., Malavieille, J., & Bokun, A. N. (1995). A mechanism for syncollisional rock exhumation and associated normal fault-
ing: Results from physical modelling. Earth and Planetary Science Letters, 132(1–4), 225–232. https://doi.org/10.1016/0012-821x(95)00042-b
Cherniak, D. J., Lanford, W. A., & Ryerson, F. J. (1991). Lead diffusion in apatite and zircon using ion implantation and Rutherford backscatter-
ing techniques. Geochimica et Cosmochimica Acta, 55(6), 1663–1673. https://doi.org/10.1016/0016-7037(91)90137-t
Chertova, M. V., Spakman, W., Geenen, T., Van Den Berg, A. P., & Van Hinsbergen, D. J. J. (2014). Underpinning tectonic reconstructions of
the western Mediterranean region with dynamic slab evolution from 3D numerical modeling. Journal of Geophysical Research: Solid Earth,
119(7), 5876–5902. https://doi.org/10.1002/2014jb011150
Chew, D. M., & Spikings, R. A. (2021). Apatite U-Pb thermochronology: A review. Minerals, 11(10), 1095. https://doi.org/10.3390/min11101095
Civiero, C., Custódio, S., Duarte, J. C., Mendes, V. B., & Faccenna, C. (2020). Dynamics of the Gibraltar arc system: A complex interaction
between plate convergence, slab pull, and mantle flow. Journal of Geophysical Research: Solid Earth, 125(7), e2019JB018873. https://doi.
org/10.1029/2019jb018873
Cloos, M. (1982). Flow melanges: Numerical modeling and geologic constraints on their origin in the Franciscan subduction complex, California.
Geological Society of America Bulletin, 93(4), 330–345. https://doi.org/10.1130/0016-7606(1982)93<330:fmnmag>2.0.co;2
Cloos, M. (1993). Lithospheric buoyancy and collisional orogenesis: Subduction of oceanic plateaus, continental margins, island arcs, spreading ridges,
and seamounts. Geological Society of America Bulletin, 105(6), 715–737. https://doi.org/10.1130/0016-7606(1993)105<0715:lbacos>2.3.co;2
Cloos, M., & Shreve, R. L. (1988). Subduction-channel model of prism accretion, melange formation, sediment subduction, and subduction
erosion at convergent plate margins: 1. Background and description. Pure and Applied Geophysics, 128(3), 455–500. https://doi.org/10.1007/
bf00874548
Collot, J. Y., Agudelo, W., Ribodetti, A., & Marcaillou, B. (2008). Origin of a crustal splay fault and its relation to the seismogenic zone and
underplating at the erosional north Ecuador–south Colombia oceanic margin. Journal of Geophysical Research, 113(B12), B12102. https://
doi.org/10.1029/2008jb005691
Comas, M. C., Platt, J. P., Soto, J. I., & Watts, A. B. (1999). 44. The origin and tectonic history of the Alboran Basin: Insights from Leg 161
results. In Proceedings of the Ocean Drilling Program Scientific Results (Vol. 161,pp.555–580).
Condit, C. B., French, M. E., Hayles, J. A., Yeung, L. Y., Chin, E. J., & Lee, C. T. A. (2022). Rheology of metasedimentary rocks at the base of
the subduction seismogenic zone. Geochemistry, Geophysics, Geosystems, 23(2), e2021GC010194. https://doi.org/10.1029/2021gc010194
Constenius, K. N., Esser, R. P., & Layer, P.W. (2003). Extensional collapse of the Charleston-Nebo salient and its relationship to space-time
variations in Cordilleran orogenic belt tectonism and continental stratigraphy. Rocky Mountain Section (SEPM).
Crespo-Blanc, A. (1995). Interference pattern of extensional fault systems: A case study of the Miocene rifting of the Alboran basement (North of
Sierra Nevada, Betic Chain). Journal of Structural Geology, 17(11), 1559–1569. https://doi.org/10.1016/0191-8141(95)e0044-d
de la Peña, L. G., Ranero, C. R., Gràcia, E., & Booth-Rea, G. (2021). The evolution of the westernmost Mediterranean basins. Earth-Science
Reviews, 214, 103445. https://doi.org/10.1016/j.earscirev.2020.103445
de Lis Mancilla, F., Booth-Rea, G., Stich, D., Pérez-Peña, J. V., Morales, J., Azañón, J. M., etal. (2015). Slab rupture and delamination under the
Betics and Rif constrained from receiver functions. Tectonophysics, 663, 225–237. https://doi.org/10.1016/j.tecto.2015.06.028
de Jong, K. (1993a). Large-scale polyphase deformation of a coherent HP/LT metamorphic unit: The Mulhacén Complex in the eastern Sierra de
Ios Filabres (Betic Zone, SE Spain). Geologie en Mijnbouw, 71, 327–336.
de Jong, K. (1993b). The tectono-metamorphic and chronologic development of the Betic Zone (SE Spain) with implications for the geodynamic
evolution of the western Mediterranean area. Proceedings of the Koninklijke Nederlandse Akademie van Wetenschappen. Series C. Biological
and Medical Sciences, 96, 295–333.
de Jong, K. (2003). Very fast exhumation of high-pressure metamorphic rocks with excess
40Ar and inherited
87Sr, Betic Cordilleras, southern
Spain. Lithos, 70(3–4), 91–110. https://doi.org/10.1016/s0024-4937(03)00094-x
De Jong, K., Féraud, G., Ruffet, G., Amouric, M., & Wijbrans, J. R. (2001). Excess argon incorporation in phengite of the Mulhacén Complex:
Submicroscopic illitization and fluid ingress during late Miocene extension in the Betic Zone, south-eastern Spain.
Dewey, J. F., Helman, M. L., Knott, S. D., Turco, E., & Hutton, D. H. W. (1989). Kinematics of the western Mediterranean. Geological Society,
London, Special Publications, 45(1), 265–283. https://doi.org/10.1144/gsl.sp.1989.045.01.15
Doin, M. P., & Henry, P. (2001). Subduction initiation and continental crust recycling: The roles of rheology and eclogitization. Tectonophysics,
342(1–2), 163–191. https://doi.org/10.1016/s0040-1951(01)00161-5

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
29 of 33
Duggen, S., Hoernle, K., Klügel, A., Geldmacher, J., Thirlwall, M., Hauff, F., etal. (2008). Geochemical zonation of the Miocene Alborán Basin
volcanism (westernmost Mediterranean): Geodynamic implications. Contributions to Mineralogy and Petrology, 156(5), 577–593. https://doi.
org/10.1007/s00410-008-0302-4
Duggen, S., Hoernle, K., van den Bogaard, P., & Harris, C. (2004). Magmatic evolution of the Alboran region: The role of subduction in forming
the western Mediterranean and causing the Messinian Salinity Crisis. Earth and Planetary Science Letters, 218(1–2), 91–108. https://doi.
org/10.1016/s0012-821x(03)00632-0
Duggen, S., Hoernle, K., Van den Bogaard, P., Rüpke, L., & Phipps Morgan, J. (2003). Deep roots of the Messinian salinity crisis. Nature,
422(6932), 602–606. https://doi.org/10.1038/nature01553
Dyja, V., Hibsch, C., Tarantola, A., Cathelineau, M., Boiron, M. C., Marignac, C., etal. (2016). From deep to shallow fluid reservoirs: Evolution
of fluid sources during exhumation of the Sierra Almagrera, Betic Cordillera, Spain. Geofluids, 16(1), 103–128. https://doi.org/10.1111/
gfl.12139
Egeler, C. G., & Simon, O. J. (1969). Orogenic evolution of the Betic Zone (Betic Cordilleras, Spain), with emphasis on the nappe structures.
Geologie en Mijnbouw, 48(3), 296–305.
Esteban, J. J., Tubía, J. M., Cuevas, J., Vegas, N., Sergeev, S., & Larionov, A. (2011). Peri-Gondwanan provenance of pre-Triassic metamor-
phic sequences in the western Alpujarride nappes (Betic Cordillera, southern Spain). Gondwana Research, 20(2–3), 443–449. https://doi.
org/10.1016/j.gr.2010.11.006
Faccenna, C., Piromallo, C., Crespo-Blanc, A., Jolivet, L., & Rossetti, F. (2004). Lateral slab deformation and the origin of the western Mediter-
ranean arcs. Tectonics, 23(1), TC1012. https://doi.org/10.1029/2002tc001488
French, M. E., & Zhu, W. (2017). Slow fault propagation in serpentinite under conditions of high pore fluid pressure. Earth and Planetary Science
Letters, 473, 131–140. https://doi.org/10.1016/j.epsl.2017.06.009
Frizon de Lamotte, D., Saint Bezar, B., Bracène, R., & Mercier, E. (2000). The two main steps of the Atlas building and geodynamics of the
western Mediterranean. Tectonics, 19(4), 740–761. https://doi.org/10.1029/2000tc900003
Galindo-Zaldivar, J., Gil, A. J., Borque, M. J., González-Lodeiro, F., Jabaloy, A., Marın-Lechado, C., etal. (2003). Active faulting in the internal
zones of the central Betic Cordilleras (SE, Spain). Journal of Geodynamics, 36(1–2), 239–250. https://doi.org/10.1016/s0264-3707(03)00049-8
Galindo-Zaldívar, J., González-Lodeiro, F., & Jabaloy, A. (1993). Stress and palaeostress in the Betic-Rif cordilleras (Miocene to the present).
Tectonophysics, 227(1–4), 105–126. https://doi.org/10.1016/0040-1951(93)90090-7
Garcia-Castellanos, D., & Villaseñor, A. (2011). Messinian salinity crisis regulated by competing tectonics and erosion at the Gibraltar arc.
Nature, 480(7377), 359–363. https://doi.org/10.1038/nature10651
García-Dueñas, V., Martinez Martinez, J. M., Orozco, M., & Soto, J. I. (1988). Plis-nappes, cisaillements syn-à post-métamorphiques et cisaille-
ment ductiles-fragiles en distension dans les Nevado-Filábrides (Cordillères Bétiques, Espagne). Comptes rendus de l'Académie des sciences.
Série 2, Mécanique, Physique, Chimie, Sciences de l'univers, Sciences de la Terre, 307(11), 1389–1395.
Gautier, P., Brun, J. P., Moriceau, R., Sokoutis, D., Martinod, J., & Jolivet, L. (1999). Timing, kinematics and cause of Aegean extension: A scenario
based on a comparison with simple analogue experiments. Tectonophysics, 315(1–4), 31–72. https://doi.org/10.1016/s0040-1951(99)00281-4
Gerya, T. V., Stöckhert, B., & Perchuk, A. L. (2002). Exhumation of high-pressure metamorphic rocks in a subduction channel: A numerical
simulation. Tectonics, 21(6), 6-1–6-19. https://doi.org/10.1029/2002tc001406
Gómez de la Peña, L., Grevemeyer, I., Kopp, H., Díaz, J., Gallart, J., Booth-Rea, G., etal. (2020). The lithospher ic structure of the Gibraltar Arc System
from wide-angle seismic data. Journal of Geophysical Research: Solid Earth, 125(9), e2020JB019854. https://doi.org/10.1029/2020jb019854
Gómez-Pugnaire, M. T., & Fernández-Soler, J. M. (1987). High-pressure metamorphism in metabasites from the Betic Cordilleras (SE Spain)
and its evolution during the Alpine orogeny. Contributions to Mineralogy and Petrology, 95(2), 231–244. https://doi.org/10.1007/bf00381273
Gómez-Pugnaire, M. T., & Franz, G. (1988). Metamorphic evolution of the Palaeozoic series of the Betic Cordilleras (Nevado-Filábride Complex,
SE Spain) and its relationship with the alpine orogeny. Geologische Rundschau, 77(3), 619–640. https://doi.org/10.1007/bf01830174
Gómez-Pugnaire, M. T., Franz, G., & Sánchez-Vizcaino, V. L. (1994). Retrograde formation of NaCl-scapolite in high pressure metaevaporites
from the Cordilleras Béticas (Spain). Contributions to Mineralogy and Petrology, 116(4), 448–461. https://doi.org/10.1007/bf00310911
Gómez-Pugnaire, M. T., Galindo-Zaldívar, J., Rubatto, D., González-Lodeiro, F., Lopez SanchezVizcaino, V., & Jabaloy, A. (2004). A reinterpre-
tation of the Nevado-Filábride and Alpujárride complexes (Betic Cordillera): Field, petrography and U-Pb ages from orthogneisses (western
Sierra Nevada, S Spain). Schweizerische Mineralogische und Petrographische Mitteilungen, 84(3), 303322.
Gómez-Pugnaire, M. T., Rubatto, D., Fernández-Soler, J. M., Jabaloy, A., López-SánchezVizcaíno, V., González-Lodeiro, F., et al. (2012).
Late Variscan magmatism in the Nevado-Filábride Complex: U-Pb geochronologic evidence for the preMesozoic nature of the deepest Betic
complex (SE Spain). Lithos, 146, 93–111. https://doi.org/10.1016/j.lithos.2012.03.027
González-Casado, J. M., Casquet, C., Martínez-Martínez, J. M., & García-Dueñas, V. (1995). Retrograde evolution of quartz segregations from
the Dos Picos shear zone in the Nevado-Filabride Complex (Betic chains, Spain). Evidence from fluid inclusions and quartz c-axis fabrics.
Geologische Rundschau, 84(1), 175–186.
Gutscher, M. A. (2012). Subduction beneath Gibraltar? Recent studies provide answers. Eos, Transactions American Geophysical Union, 93(13),
133–134. https://doi.org/10.1029/2012eo130001
Harvey, K. M., Walker, S., Starr, P.G., Penniston-Dorland, S. C., Kohn, M. J., & Baxter, E. F. (2021). A mélange of subduction ages: Constraints
on the timescale of shear zone development and underplating at the subduction interface, Catalina Schist (CA, USA). Geochemistry, Geophys-
ics, Geosystems, 22(9), e2021GC009790. https://doi.org/10.1029/2021gc009790
Heilbronner, R., & Tullis, J. (2002). The effect of static annealing on microstructures and crystallographic preferred orientations of quartzites
experimentally deformed in axial compression and shear. Special Publication - Geological Society of London, 200(1), 191–218. https://doi.
org/10.1144/gsl.sp.2001.200.01.12
Heit, B., Mancilla, F. D. L., Yuan, X., Morales, J., Stich, D., Martín, R., & Molina-Aguilera, A. (2017). Tearing of the mantle lithosphere along
the intermediate-depth seismicity zone beneath the Gibraltar Arc: The onset of lithospheric delamination. Geophysical Research Letters, 44(9),
4027–4035. https://doi.org/10.1002/2017gl073358
Henrichs, I. A., O'Sullivan, G., Chew, D. M., Mark, C., Babechuk, M. G., McKenna, C., & Emo, R. (2018). The trace element and U-Pb system-
atics of metamorphic apatite. Chemical Geology, 483, 218–238. https://doi.org/10.1016/j.chemgeo.2017.12.031
Henrys, S., Wech, A., Sutherland, R., Stern, T., Savage, M., Sato, H., etal. (2013). SAHKE geophysical transect reveals crustal and subduc-
tion zone structure at the southern Hikurangi margin, New Zealand. Geochemistry, Geophysics, Geosystems, 14(7), 2063–2083. https://doi.
org/10.1002/ggge.20136
Jabaloy-Sánchez, A., Talavera, C., Gómez-Pugnaire, M. T., López-Sánchez-Vizcaíno, V., Vázquez-Vílchez, M., Rodríguez-Peces, M. J., & Evans,
N. J. (2018). U-Pb ages of detrital zircons from the Internal Betics: A key to deciphering paleogeographic provenance and tectono-stratigraphic
evolution. Lithos, 318, 244–266. https://doi.org/10.1016/j.lithos.2018.07.026

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
30 of 33
Jabaloy-Sánchez, A., Talavera, C., Rodríguez-Peces, M. J., Vázquez-Vílchez, M., & Evans, N. J. (2021). U-Pb geochronology of detrital and igne-
ous zircon grains from the Águilas Arc in the Internal Betics (SE Spain): Implications for Carboniferous-Permian paleogeography of Pangea.
Gondwana Research, 90, 135–158. https://doi.org/10.1016/j.gr.2020.10.013
Jackson, S. E., Pearson, N. J., Griffin, W. L., & Belousova, E. A. (2004). The application of laser ablation-inductively coupled plasma-mass spec-
trometry to in situ U–Pb zircon geochronology. Chemical Geology, 211(1–2), 47–69. https://doi.org/10.1016/j.chemgeo.2004.06.017
Jammes, S., Manatschal, G., Lavier, L., & Masini, E. (2009). Tectonosedimentary evolution related to extreme crustal thinning ahead of a propa-
gating ocean: Example of the western Pyrenees. Tectonics, 28(4), TC4012. https://doi.org/10.1029/2008tc002406
Jolivet, L., Faccenna, C., Goffé, B., Burov, E., & Agard, P. (2003). Subduction tectonics and exhumation of high-pressure metamorphic rocks in
the Mediterranean orogens. American Journal of Science, 303(5), 353–409. https://doi.org/10.2475/ajs.303.5.353
Jolivet, L., Raimbourg, H., Labrousse, L., Avigad, D., Leroy, Y., Austrheim, H., & Andersen, T. B. (2005). Softening trigerred by eclogitiza-
tion, the first step toward exhumation during continental subduction. Earth and Planetary Science Letters, 237(3–4), 532–547. https://doi.
org/10.1016/j.epsl.2005.06.047
Kampschuur, W., & Rondeel, H. E. (1975). The origin of the Betic orogen, southern Spain. Tectonophysics, 27(1), 39–56. https://doi.
org/10.1016/0040-1951(75)90047-5
Kirchner, K. L., Behr, W. M., Loewy, S., & Stockli, D. F. (2016). Early Miocene subduction in the western Mediterranean: Constraints from Rb-Sr
multimineral isochron geochronology. Geochemistry, Geophysics, Geosystems, 17(5), 1842–1860. https://doi.org/10.1002/2015gc006208
Kohn, M. J., & Kelly, N. M. (2018). Petrology and geochronology of metamorphic zircon. Microstructural geochronology: Planetary records
down to atom scale (pp.35–61).
Kotowski, A. J., & Behr, W. M. (2019). Length scales and types of heterogeneities along the deep subduction interface: Insights from exhumed
rocks on Syros Island, Greece. Geosphere, 15(4), 1038–1065. https://doi.org/10.1130/ges02037.1
Kotowski, A. J., Cisneros, M., Behr, W. M., Stockli, D. F., Soukis, K., Barnes, J. D., & OrtegaArroyo, D. (2022). Subduction, underplat-
ing, and return flow recorded in the Cycladic Blueschist Unit exposed on Syros, Greece. Tectonics, 41(6), e2020TC006528. https://doi.
org/10.1029/2020tc006528
Laborda-López, C., Aguirre, J., Donovan, S. K., Navas-Parejo, P., & Rodríguez, S. (2015). Fossil assemblages and biostratigraphy of metamor-
phic rocks of the Nevado-Filábride Complex from the Águilas tectonic arc (SE Spain).
Levander, A., Bezada, M. J., Niu, F., Humphreys, E. D., Palomeras, I., Thurner, S. M., etal. (2014). Subduction-driven recycling of continental
margin lithosphere. Nature, 515(7526), 253–256. https://doi.org/10.1038/nature13878
Li, B., & Massonne, H. J. (2018). Two Tertiary metamorphic events recognized in high-pressure metapelites of the Nevado-Filábride Complex
(Betic Cordillera, S Spain). Journal of Metamorphic Geology, 36(5), 603–630. https://doi.org/10.1111/jmg.12312
Li, J., Shillington, D. J., Bécel, A., Nedimović, M. R., Webb, S. C., Saffer, D. M., etal. (2015). Downdip variations in seismic reflection charac-
ter: Implications for fault structure and seismogenic behavior in the Alaska subduction zone. Journal of Geophysical Research: Solid Earth,
120(11), 7883–7904. https://doi.org/10.1002/2015jb012338
Liati, A., Gebauer, D., & Fanning, C. M. (2009). Geochronological evolution of HP metamorphic rocks of the Adula nappe, Central Alps, in
pre-Alpine and Alpine subduction cycles. Journal of the Geological Society, 166(4), 797–810. https://doi.org/10.1144/0016-76492008-033
Lonergan, L., & White, N. (1997). Origin of the Betic-Rif mountain belt. Tectonics, 16(3), 504–522. https://doi.org/10.1029/96tc03937
López Sánchez-Vizcaíno, V., Trommsdorff, V., Gómez-Pugnaire, M. T., Garrido, C. J., Müntener, O., & Connolly, J. A. D. (2005). Petrology of
titanian clinohumite and olivine at the highpressure breakdown of antigorite serpentinite to chlorite harzburgite (Almirez Massif, S. Spain).
Contributions to Mineralogy and Petrology, 149(6), 627–646. https://doi.org/10.1007/s00410-005-0678-3
López Sánchez-Vizcaíno, V. L., Rubatto, D., Gómez-Pugnaire, M. T., Trommsdorff, V., & Müntener, O. (2001). Middle Miocene
high-pressure metamorphism and fast exhumation of the Nevado-Filábride Complex, SE Spain. Terra Nova, 13(5), 327–332. https://doi.
org/10.1046/j.1365-3121.2001.00354.x
Madarieta-Txurruka, A., Galindo-Zaldívar, J., González-Castillo, L., Peláez, J. A., Ruiz-Armenteros, A. M., Henares, J., etal. (2021). High-and
low-angle normal fault activity in a collisional orogen: The Northeastern Granada Basin (Betic Cordillera). Tectonics, 40(7), e2021TC006715.
https://doi.org/10.1029/2021TC006715
Marquardt, H., & Miyagi, L. (2015). Slab stagnation in the shallow lower mantle linked to an increase in mantle viscosity. Nature Geoscience,
8(4), 311–314. https://doi.org/10.1038/ngeo2393
Marrone, S., Monié, P., Rossetti, F., Lucci, F., Theye, T., Bouybaouene, M. L., & Zaghloul, M. N. (2021). The pressure–temperature–time–defor-
mation history of the Beni Mzala unit (Upper Sebtides, Rif belt, Morocco): Refining the Alpine tectono-metamorphic evolution of the Alboran
Domain of the western Mediterranean. Journal of Metamorphic Geology, 39(5), 591–615. https://doi.org/10.1111/jmg.12587
Marsh, J. H., & Stockli, D. F. (2015). Zircon U–Pb and trace element zoning characteristics in an anatectic granulite domain: Insights from
LASS-ICP-MS depth profiling. Lithos, 239, 170–185. https://doi.org/10.1016/j.lithos.2015.10.017
Martínez-Martínez, J. M., & Azañón, J. M. (1997). Mode of extensional tectonics in the southeastern Betics (SE Spain): Implications for the
tectonic evolution of the peri-Alborán orogenic system. Tectonics, 16(2), 205–225. https://doi.org/10.1029/97tc00157
Martínez-Martínez, J. M., Soto, J. I., & Balanyá, J. C. (2002). Orthogonal folding of extensional detachments: Structure and origin of the Sierra
Nevada elongated dome (Betics, SE Spain). Tectonics, 21(3), 3-1–3-20. https://doi.org/10.1029/2001tc001283
Martínez-Martínez, J. M., Torres-Ruiz, J., Pesquera, A., & Gil-Crespo, P.P. (2010). Geological relationships and U-Pb zircon and
40Ar/
39Ar
tourmaline geochronology of gneisses and tourmalinites from the Nevado–Filabride complex (western Sierra Nevada, Spain): Tectonic impli-
cations. Lithos, 119(3–4), 238–250. https://doi.org/10.1016/j.lithos.2010.07.002
Martin-Rojas, I., Somma, R., Delgado, F., Estévez, A., Iannace, A., Perrone, V., & Zamparelli, V. (2009). Triassic continental rifting of Pangaea:
Direct evidence from the Alpujárride carbonates, Betic Cordillera, SE Spain. Journal of the Geological Society, 166(3), 447–458. https://doi.
org/10.1144/0016-76492008-091
Melnick, D., Bookhagen, B., Echtler, H. P., & Strecker, M. R. (2006). Coastal deformation and great subduction earthquakes, Isla Santa María,
Chile (37°S). Geological Society of America Bulletin, 118(11–12), 1463–1480. https://doi.org/10.1130/b25865.1
Menant, A., Angiboust, S., & Gerya, T. (2019). Stress-driven fluid flow controls long-term megathrust strength and deep accretionary dynamics.
Scientific Reports, 9(1), 1–11. https://doi.org/10.1038/s41598-019-46191-y
Menzel, M. D., Garrido, C. J., López Sánchez-Vizcaíno, V., Hidas, K., & Marchesi, C. (2019). Subduction metamorphism of serpentinite-hosted
carbonates beyond antigoriteserpentinite dehydration (Nevado-Filábride Complex, Spain). Journal of Metamorphic Geology, 37(5), 681–715.
https://doi.org/10.1111/jmg.12481
Monié, P., Galindo-Zaldivar, J., Lodeiro, F. G., Goffe, B., & Jabaloy, A. (1991).
40Ar/
39Ar geochronology of Alpine tectonism in the Betic
Cordilleras (southern Spain). Journal of the Geological Society, 148(2), 289–297. https://doi.org/10.1144/gsjgs.148.2.0289

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
31 of 33
Moore, J. C., Diebold, J., Fisher, M. A., Sample, J., Brocher, T., Talwani, M., etal. (1991). EDGE deep seismic reflection transect of the eastern
Aleutian arc-trench layered lower crust reveals underplating and continental growth. Geology, 19(5), 420–424. https://doi.org/10.1130/0091-
7613(1991)019<0420:edsrto>2.3.co;2
Moragues, L., Ruano, P., Azañón, J. M., Garrido, C. J., Hidas, K., & Booth Rea, G. (2021). Two Cenozoic extensional phases in Mallorca and their
bearing on the geodynamic evolution of the western Mediterranean. Tectonics, 40(11), e2021TC006868. https://doi.org/10.1029/2021tc006868
Nance, R. D., Gutiérrez-Alonso, G., Duncan Keppie, J., Linnemann, U., Brendan Murphy, J., Quesada, C., etal. (2012). A brief history of the
Rheic Ocean. Geoscience Frontiers, 3(2), 125–135. https://doi.org/10.1016/j.gsf.2011.11.008
Odlum, M. L., Levy, D. A., Stockli, D. F., Stockli, L. D., & DesOrmeau, J. W. (2022). Deformation and metasomatism recorded by single-grain
apatite petrochronology. Geology, 50(6), 697–703. https://doi.org/10.1130/g49809.1
Odlum, M. L., & Stockli, D. F. (2020). Geochronologic constraints on deformation and metasomatism along an exhumed mylonitic shear zone
using apatite U-Pb, geochemistry, and microtextural analysis. Earth and Planetary Science Letters, 538, 116177. https://doi.org/10.1016/j.
epsl.2020.116177
O'Sullivan, G., Chew, D., Kenny, G., Henrichs, I., & Mulligan, D. (2020). The trace element composition of apatite and its application to detrital
provenance studies. Earth-Science Reviews, 201, 103044. https://doi.org/10.1016/j.earscirev.2019.103044
Padrón-Navarta, J. A., Hermann, J., Garrido, C. J., López Sánchez-Vizcaíno, V., & Gómez-Pugnaire, M. T. (2010). An experimental investiga-
tion of antigorite dehydration in natural silica-enriched serpentinite. Contributions to Mineralogy and Petrology, 159(1), 25–42. https://doi.
org/10.1007/s00410-009-0414-5
Passchier, C. W., & Trouw, R. A. (2005). Microtectonics. Springer Science & Business Media.
Paton, C., Woodhead, J. D., Hellstrom, J. C., Hergt, J. M., Greig, A., & Maas, R. (2010). Improved laser ablation U-Pb zircon geochronology through
robust downhole fractionation correction. Geochemistry, Geophysics, Geosystems, 11(3), Q0AA06. https://doi.org/10.1029/2009gc002618
Pedrera, A., Ruiz-Constán, A., García-Senz, J., Azor, A., Marín-Lechado, C., Ayala, C., etal. (2020). Evolution of the South-Iberian paleomar-
gin: From hyperextension to continental subduction. Journal of Structural Geology, 138, 104122. https://doi.org/10.1016/j.jsg.2020.104122
Pfiffner, O. A. (2016). Basement-involved thin-skinned and thick-skinned tectonics in the Alps. Geological Magazine, 153(5–6), 1085–1109.
https://doi.org/10.1017/s0016756815001090
Piana Agostinetti, N., & Faccenna, C. (2018). Deep structure of Northern Apennines subduction orogen (Italy) as revealed by a joint interpretation
of passive and active seismic data. Geophysical Research Letters, 45(9), 4017–4024. https://doi.org/10.1029/2018gl077640
Platt, J. P. (1986). Dynamics of orogenic wedges and the uplift of high-pressure metamorphic rocks. The Geological Society of America Bulletin,
97(9), 1037–1053. https://doi.org/10.1130/0016-7606(1986)97<1037:doowat>2.0.co;2
Platt, J. P. (1993). Exhumation of high-pressure rocks: A review of concepts and processes. Terra Nova, 5(2), 119–133. https://doi.
org/10.1111/j.1365-3121.1993.tb00237.x
Platt, J. P., Anczkiewicz, R., Soto, J. I., Kelley, S. P., & Thirlwall, M. (2006). Early Miocene continental subduction and rapid exhumation in the
western Mediterranean. Geology, 34(11), 981–984. https://doi.org/10.1130/g22801a.1
Platt, J. P., Behr, W. M., Johanesen, K., & Williams, J. R. (2013). The Betic-Rif arc and its orogenic hinterland: A review. Annual Review of Earth
and Planetary Sciences, 41(1), 313357–357. https://doi.org/10.1146/annurev-earth-050212-123951
Platt, J. P., Kelley, S. P., Car ter, A., & Orozco, M. (2005). Timing of tectonic events in the Alpujárride Complex, Betic Cordillera, southern Spain.
Journal of the Geological Society, 162(3), 451–462. https://doi.org/10.1144/0016-764903-039
Platt, J. P., Soto, J. I., Whitehouse, M. J., Hurford, A. J., & Kelley, S. P. (1998). Thermal evolution, rate of exhumation, and tectonic signif-
icance of metamorphic rocks from the floor of the Alboran extensional basin, western Mediterranean. Tectonics, 17(5), 671–689.
https://doi.org/10.1029/98tc02204
Porkoláb, K., Matenco, L., Hupkes, J., Willingshofer, E., Wijbrans, J., van Schrojenstein Lantman, H., & van Hinsbergen, D. J. (2022). Tectonic
evolution of the Nevado-Filábride Complex (Sierra de Los Filábres, Southeastern Spain): Insights from new structural and geochronological
data. Tectonics, 41(8), e2021TC006922. https://doi.org/10.1029/2021tc006922
Poulaki, E. M., & Stockli, D. F. (2022). Paleotectonic evolution of the Western Mediterranean: Provenance insights from the Internal Betics,
Southern Spain. Frontiers of Earth Science, 10, 929502.
Poulaki, E. M., Stockli, D. F., Flansburg, M. E., Gevedon, M. L., Stockli, L. D., Barnes, J. D., etal. (2021). Zircon U-Pb and geochemical
signatures in high-pressure, low-temperature metamorphic rocks as recorders of subduction zone processes, Sikinos and Ios islands, Greece.
Chemical Geology, 582, 120447. https://doi.org/10.1016/j.chemgeo.2021.120447
Poulaki, E. M., Stockli, D. F., Flansburg, M. E., & Soukis, K. (2019). Zircon U-Pb chronostratigraphy and provenance of the Cycladic Blueschist
Unit and the nature of the contact with the Cycladic Basement on Sikinos and Ios islands, Greece. Tectonics, 38(10), 3586–3613. https://doi.
org/10.1029/2018tc005403
Puga, E., De Federico, A. D., & Nieto, J. M. (2002). Tectonostratigraphic subdivision and petrological characterisation of the deepest complexes
of the Betic zone: A review. Geodinamica Acta, 15(1), 23–43. https://doi.org/10.1016/s0985-3111(01)01077-4
Puga, E., Fanning, C. M., Nieto, J. M., & De Federico, A. D. (2005). Recrystallization textures in zircon generated by ocean-floor and
eclogite-facies metamorphism: A cathodoluminescence and U–Pb SHRIMP study, with constraints from REE elements. The Canadian Miner-
alogist, 43(1), 183–202. https://doi.org/10.2113/gscanmin.43.1.183
Puga, E., Nieto, J. M., & De Federico, A. D. (2000). Contrasting P–T paths in eclogites of the Betic ophiolitic association, Mulhacén complex,
southeastern Spain. The Canadian Mineralogist, 38(5), 1137–1161. https://doi.org/10.2113/gscanmin.38.5.1137
Rehault, J. P., Boillot, G., & Mauffret, A. (1984). The western Mediterranean basin geological evolution. Marine Geology, 55(3–4), 447–477.
https://doi.org/10.1016/0025-3227(84)90081-1
Reinhardt, L. J., Dempster, T. J., Shroder Jr., J. F., & Persano, C. (2007). Tectonic denudation and topographic development in the Spanish Sierra
Nevada. Tectonics, 26(3), TC3001. https://doi.org/10.1029/2006tc001954
Ring, U., Brandon, M. T., Willett, S. D., & Lister, G. S. (1999). Exhumation processes. Geological Society, London, Special Publications, 154(1),
1–27. https://doi.org/10.1144/gsl.sp.1999.154.01.01
Rodríguez-Cañero, R., Jabaloy-Sánchez, A., Navas-Parejo, P., & Martín-Algarra, A. (2018). Linking Palaeozoic palaeogeography of the Betic
Cordillera to the Variscan Iberian Massif: New insight through the first conodonts of the Nevado-Filábride Complex. International Journal of
Earth Sciences, 107(5), 1791–1806. https://doi.org/10.1007/s00531-017-1572-8
Rodríguez-Fernández, J., Azor, A., & Miguel Azañón, J. (2011). The Betic intramontane basins (SE Spain): Stratigraphy, subsidence, and tectonic
history. Tectonics of sedimentary basins: Recent advances (pp.461–479).
Rosenbaum, G., Lister, G. S., & Duboz, C. (2002). Relative motions of Africa, Iberia and Europe during Alpine orogeny. Tectonophysics,
359(1–2), 117–129. https://doi.org/10.1016/s0040-1951(02)00442-0
Rossetti, F., Faccenna, C., & Crespo-Blanc, A. (2005). Structural and kinematic constraints to the exhumation of the Alpujárride Complex
(Central Betic Cordillera, Spain). Journal of Structural Geology, 27(2), 199–216. https://doi.org/10.1016/j.jsg.2004.10.008

Geochemistry, Geophysics, Geosystems
POULAKI ETAL.
10.1029/2022GC010802
32 of 33
Royden, L. H. (1993). Evolution of retreating subduction boundaries formed during continental collision. Tectonics, 12(3), 629–638. https://doi.
org/10.1029/92tc02641
Rubatto, D. (2002). Zircon trace element geochemistry: Partitioning with garnet and the link between U–Pb ages and metamorphism. Chemical
Geology, 184(1–2), 123–138. https://doi.org/10.1016/s0009-2541(01)00355-2
Ruiz-Cruz, M. D., de Galdeano, C. S., & Santamaría, A. (2015). Petrology and thermobarometric estimates for metasediments, orthogneisses,
and eclogites from the Nevado-Filábride complex in the western Sierra Nevada (Betic Cordillera, Spain). The Canadian Mineralogist, 53(6),
1083–1107. https://doi.org/10.3749/canmin.1500037
Ruiz-Fuentes, A., & Aerden, D. G. (2018). Transposition of foliations and superposition of lineations during polyphase deformation in the
Nevado-Filabride Complex: Tectonic implications. International Journal of Earth Sciences, 107(6), 1975–1988. https://doi.org/10.1007/
s00531-017-1582-6
Rutter, E. H. (1983). Pressure solution in nature, theory and experiment. Journal of the Geological Society, 140(5), 725–740. https://doi.
org/10.1144/gsjgs.140.5.0725
Sandmann, S., Nagel, T. J., Herwartz, D., Fonseca, R. O., Kurzawski, R. M., Münker, C., & Froitzheim, N. (2014). Lu–Hf garnet systematics of
a polymetamorphic basement unit: New evidence for coherent exhumation of the Adula Nappe (Central Alps) from eclogite-facies conditions.
Contributions to Mineralogy and Petrology, 168(5), 1–21. https://doi.org/10.1007/s00410-014-1075-6
Santamaría-López, Á., Lanari, P., & Sanz de Galdeano, C. S. (2019). Deciphering the tectonometamorphic evolution of the Nevado-Filábride
complex (Betic Cordillera, Spain)—A petrochronological study. Tectonophysics, 767, 128158. https://doi.org/10.1016/j.tecto.2019.06.028
Santamaría-López, Á., & Sanz de Galdeano, C. (2018). SHRIMP U–Pb detrital zircon dating to check subdivisions in metamorphic complexes: A
case of study in the Nevado–Filábride complex (Betic Cordillera, Spain). International Journal of Earth Sciences, 107(7), 2539–2552. https://
doi.org/10.1007/s00531-018-1613-y
Sanz de Galdeano, C., & Santamaría-López, Á. (2019). The lithological sequence of the NevadoFilábride complex (Betic internal zone) in the
Sierras Nevada and filabres La secuencia litológica del Complejo Nevado-Filábride (Zona Interna Bética) en las sierras Nevada y de los
Filabres.
Saspiturry, N., Cochelin, B., Razin, P., Leleu, S., Lemirre, B., Bouscary, C., etal. (2019). Tectono-sedimentary evolution of a rift system
controlled by Permian postorogenic extension and metamorphic core complex formation (Bidarray Basin and Ursuya dome, Western Pyre-
nees). Tectonophysics, 768, 228180. https://doi.org/10.1016/j.tecto.2019.228180
Schoene, B., & Bowring, S. A. (2006). U–Pb systematics of the McClure mountain syenite: Thermochronological constraints on the age of
the
40Ar/
39Ar standard MMhb. Contributions to Mineralogy and Petrology, 151(5), 615–630. https://doi.org/10.1007/s00410-006-0077-4
Scholl, D. W. (2021). Seismic imaging evidence that forearc underplating built the accretionary rock record of coastal North and South America.
Geological Magazine, 158(1), 104–117. https://doi.org/10.1017/s0016756819000955
Scott, R. J., & Lister, G. S. (1992). Detachment faults: Evidence for a low-angle origin. Geology, 20(9), 833–836. https://doi.
org/10.1130/0091-7613(1992)020<0833:dfefal>2.3.co;2
Seman, S. M. (2016). The tectonostratigraphy of the Cycladic Blueschist Unit and new garnet geo/thermochronology techniques (Doctoral
dissertation).
Shreve, R. L., & Cloos, M. (1986). Dynamics of sediment subduction, melange formation, and prism accretion. Journal of Geophysical Research,
91(B10), 10229–10245. https://doi.org/10.1029/jb091ib10p10229
Sláma, J., Košler, J., Condon, D. J., Crowley, J. L., Gerdes, A., Hanchar, J. M., etal. (2008). Plešovice zircon—A new natural reference material
for U–Pb and Hf isotopic microanalysis. Chemical Geology, 249(1–2), 1–35. https://doi.org/10.1016/j.chemgeo.2007.11.005
Smye, A. J., Marsh, J. H., Vermeesch, P., Garber, J. M., & Stockli, D. F. (2018). Applications and limitations of U-Pb thermochronology to middle
and lower crustal thermal histories. Chemical Geology, 494, 1–18. https://doi.org/10.1016/j.chemgeo.2018.07.003
Stacey, J. S., & Kramers, J. D. (1975). Approximation of terrestrial lead isotope evolution by a two-stage model. Earth and Planetary Science
Letters, 26(2), 207–221. https://doi.org/10.1016/0012-821x(75)90088-6
Stampfli, G. M., & Borel, G. D. (2002). A plate tectonic model for the Paleozoic and Mesozoic constrained by dynamic plate boundaries and
restored synthetic oceanic isochrons. Earth and Planetary Science Letters, 196(1–2), 17–33. https://doi.org/10.1016/s0012-821x(01)00588-x
Stern, R. J. (2002). Subduction zones. Reviews of Geophysics, 40(4), 3-1–3-38. https://doi.org/10.1029/2001rg000108
Stöckhert, B. (2002). Stress and deformation in subduction zones: Insight from the record of exhumed metamorphic rocks. Geological Society,
London, Special Publications, 200(1), 255–274. https://doi.org/10.1144/gsl.sp.2001.200.01.15
Tarling, M. S., Smith, S. A., & Scott, J. M. (2019). Fluid overpressure from chemical reactions in serpentinite within the source region of deep
episodic tremor. Nature Geoscience, 12(12), 1034–1042. https://doi.org/10.1038/s41561-019-0470-z
Tera, F., & Wasserburg, G. J. (1972). U-Th-Pb systematics in three Apollo 14 basalts and the problem of initial Pb in lunar rocks. Earth and
Planetary Science Letters, 14(3), 281–304. https://doi.org/10.1016/0012-821x(72)90128-8
Tewksbury-Christle, C. M., Behr, W. M., & Helper, M. A. (2021). Tracking deep sediment underplating in a fossil subduction margin: Impli-
cations for interface rheology and mass and volatile recycling. Geochemistry, Geophysics, Geosystems, 22(3), e2020GC009463. https://doi.
org/10.1029/2020GC009463
Thomson, S. N., Gehrels, G. E., Ruiz, J., & Buchwaldt, R. (2012). Routine low-damage apatite UPb dating using laser ablation–multicollector–
ICPMS. Geochemistry, Geophysics, Geosystems, 13(2), Q0AA21. https://doi.org/10.1029/2011gc003928
Torii, Y., & Yoshioka, S. (2007). Physical conditions producing slab stagnation: Constraints of the Clapeyron slope, mantle viscosity, trench
retreat, and dip angles. Tectonophysics, 445(3–4), 200–209. https://doi.org/10.1016/j.tecto.2007.08.003
Van Hinsbergen, D. J., Torsvik, T. H., Schmid, S. M., Maţenco, L. C., Maffione, M., Vissers, R. L., etal. (2020). Orogenic architecture of the
Mediterranean region and kinematic reconstruction of its tectonic evolution since the Triassic. Gondwana Research, 81, 79–229. https://doi.
org/10.1016/j.gr.2019.07.009
Varas-Reus, M. I., Garrido, C. J., Marchesi, C., Bosch, D., Acosta-Vigil, A., Hidas, K., etal. (2017). Sr-Nd-Pb isotopic systematics of crustal
rocks from the western Betics (S. Spain): Implications for crustal recycling in the lithospheric mantle beneath the westernmost Mediterranean.
Lithos, 276, 45–61. https://doi.org/10.1016/j.lithos.2016.10.003
Vergés, J., & Fernàndez, M. (2012). Tethys–Atlantic interaction along the Iberia–Africa plate boundary: The Betic–Rif orogenic system. Tectono-
physics, 579, 144–172. https://doi.org/10.1016/j.tecto.2012.08.032
Vermeesch, P. (2018). IsoplotR: A free and open toolbox for geochronology. Geoscience Frontiers, 9(5), 1479–1493. https://doi.org/10.1016/j.
gsf.2018.04.001
Vissers, R. L. M., Platt, J. P., & Van der Wal, D. (1995). Late orogenic extension of the Betic Cordillera and the Alboran domain: A lithospheric
view. Tectonics, 14(4), 786–803. https://doi.org/10.1029/95tc00086

Watson, E. B., Harrison, T. M., & Ryerson, F. J. (1985). Diffusion of Sm, Sr, and Pb in fluorapatite. Geochimica et Cosmochimica Acta, 49(8),
1813–1823. https://doi.org/10.1016/0016-7037(85)90151-6
Williams, I. S. (2001). Response of detrital zircon and monazite, and their U–Pb isotopic systems, to regional metamorphism and host-
rock partial melting, Cooma Complex, southeastern Australia. Australian Journal of Earth Sciences, 48(4), 557–580. https://doi.
org/10.1046/j.1440-0952.2001.00883.x
Erratum
The originally published version of this article contained some typographical errors. In the captions for Figures 5
and 7, several numbers were inserted in error. These errors have now been corrected and this may now be consid-
ered the authoritative version of record.
Geochemistry, Geophysics, Geosystems 10.1029/2022GC010802
POULAKI ETAL. 33 of 33