Figure - uploaded by Oguz H. Göğüş
Content may be subject to copyright.
Map showing main orogenic belts in the Alpine–Mediterranean region
Red stars indicate locations of the microcontinents that underwent pre-collisional extensional deformation (inset). a, Tectonic setting of a microcontinent approaching a subduction trench. b, Back-arc extension on the overriding plate due to slab retreat (modified from Brun and Faccenna⁶). c, Interpreted extensional tectonics of a microcontinent (continental block) in the pro-plate, discussed in this article. d, Palaeotectonic interpretation for the Western Alps made by Rosenbaum and Lister³⁵ with pre-accretion locations of several microcontinents including the Sesia block. The base map in the figure was made with GeoMapApp (www.geomapapp.org) under a Creative Commons licence CC BY 4.0⁵⁶. EAF, East Anatolian Fault.

Map showing main orogenic belts in the Alpine–Mediterranean region Red stars indicate locations of the microcontinents that underwent pre-collisional extensional deformation (inset). a, Tectonic setting of a microcontinent approaching a subduction trench. b, Back-arc extension on the overriding plate due to slab retreat (modified from Brun and Faccenna⁶). c, Interpreted extensional tectonics of a microcontinent (continental block) in the pro-plate, discussed in this article. d, Palaeotectonic interpretation for the Western Alps made by Rosenbaum and Lister³⁵ with pre-accretion locations of several microcontinents including the Sesia block. The base map in the figure was made with GeoMapApp (www.geomapapp.org) under a Creative Commons licence CC BY 4.0⁵⁶. EAF, East Anatolian Fault.

Source publication
Article
Full-text available
Terrane accretion is a ubiquitous process of plate tectonics that delivers fragments of subduction-resistant lithosphere into a subduction zone, resulting in events such as ocean plateau docking or continental assembly and orogenesis. The post-collisional extension of continental terranes is a well-documented tectonic process linked with gravitatio...

Contexts in source publication

Context 1
... extension in conjunction with plate subduction and collision 4,5 . In such settings, continental lithosphere of the back-arc (overriding) environment extends, and/or the microcontinent (terrane and/or blocks) that accompanies the subducting oceanic lithosphere undergoes an extension after the collision as high-pressure exhumation occurs 6 (Fig. 1a,b). Both mechanisms infer that slab-pull forcing transmits stresses through the crust to yield a trenchward retreat of the subduction (that is, the subduction rate is faster than the plate convergence) 4 . A key aspect of these tectonic deformational events on the overriding continent or in the microcontinent terrane is their temporal ...
Context 2
... temporal occurrence: the extension is contemporaneous (syn) or proceeding (post) the collision/ subduction time of the continental block. We propose that there is another fundamental class of extensional tectonics which occurs during the pre-collisional stages of the tectonic cycle as microcontinents (terranes) drift towards a subduction zone (Fig. 1c), and that this pre-collisional episode of plate tectonic deformation has been ...
Context 3
... studies in the Western Alps suggest that the burial and exhumation of polymetamorphosed (high pressure-low temperature) Austro-alpine continental crust (including eclogites) of the Sesia-Lanzo zone (microcontinent) occurs through the development of extensional and/or detachment faulting 7 (Figs. 1 and 4a). Notably, these events occur prior to the Eocene continent-continent collision in the Alps 8 . ...
Context 4
... test quantitatively the deformational behaviour of microcontinents prior to a collision-accretion event, we used the geodynamic numerical modelling tool SOPALE 15 . SOPALE is a geodynamic code that solves plane strain deformation of viscoplastic materials using arbitrary Lagrangian-Eulerian techniques. Extended Data Fig. 1 and Extended Data Table 1 describe the configuration of the models. A full explanation of the governing equations and formulation for rheology is given in Methods and in numerous previous applications of the SOPALE code [16][17][18][19][20] ...
Context 5
... models test varying microcontinent widths from 120 to 600 km and three cases of convergence velocity: 0 cm yr -1 (lithospheric motion is driven only by the subducting ocean plate), and 2 and 4 cm yr -1 convergence velocity (as a proxy for large-scale plate tectonics, such as ridge push). Supplementary Figs. 1 and 2 show sets of additional test models that compare a range of different rheology parameters, a continental overriding plate and an additional convergence rate; the Supplementary Table lists relevant modelling parameters. Model EXP-1 has a 120-km-wide microcontinent with a 0 cm yr -1 imposed convergent rate (Fig. 2). ...
Context 6
... necessary to convert the data from uniaxial laboratory experiments into a state of stress that is independent of the choice of coordinate system 16 . The experiment set-up has a 100-km-thick microcontinent (30 km continental crust and 70 km lithospheric mantle) drifting towards an intra-oceanic subduction zone with a convergence rate of 0, 2 and 4 cm yr -1 , a 90-km-thick oceanic lithosphere (7 km oceanic crust and 83 km lithospheric mantle) and sublithospheric mantle as deep as 660 km at the closed bottom of the box (Extended Data Fig. 1). An imposed convergence velocity, if present, is applied at the right lithospheric boundary of the model by introducing new lithosphere into the box. ...
Context 7
... mantle lithosphere on the left and right boundaries of the model set-up has relatively high cohesion values (300 MPa) to prevent deformation at the model box boundaries in case of the presence of imposed convergence velocities. These cohesion values were initially chosen for practical reasons and they do not have any significant effect on the pre-collisional extension of microcontinents, as evidenced by our supplementary test models ( Supplementary Figs 1 and 2). ...

Similar publications

Chapter
Full-text available
The rise of plate tectonics theory in the 1960s contributed to a revival of the long-neglected idea of continental drift, and revolutionized Earth sciences by shifting people’s perception that continents were fixed to a belief that they were in a constant state of motion.
Preprint
Full-text available
Face-to-face double subduction systems, in which two oceanic plates are subducted toward each other, are common elements of plate tectonics. Two subduction zones in such systems are typically uneven in age and their subduction dynamics vary both temporarily and spatially and remain enigmatic. Here we use 2D geodynamic numerical modeling to show tha...
Article
Full-text available
The paradigm of plate tectonics holds that ocean plates are rigid during drift and only experience tectonic deformation at subduction zones, but new findings from the Pacific challenge this idea. Geological and geophysical evidence from the Ontong Java, Shatsky, Hess, and Manihiki oceanic plateaux indicates that extensional deformation during plate...

Citations

... Subsequently, to examine the effects of convergence velocity (u c ), we perform several experiments with values that are lower than in the reference experiment (4.5 cm yr 1 ): 3.0, 1.5, and 0.5 cm yr 1 (models 8-10). It is well known that in natural collisional settings, the presence of a small continental block (microcontinent) extending along the passive margin can add complexity not only to the architecture of the original passive margin but also to the resulting collisional orogen (Eskens et al., 2024), potentially affecting the processes of slab breakoff and tear propagation (Gün et al., 2021;Handy et al., 2010). We therefore complete our modeling set with experiments containing a microcontinent for both convergence-perpendicular (i.e., α is 0°; model 11) and oblique passive margin (i.e., α is 7.5°and 15°; models 12-13). ...
... In contrast to all previous experiments, in which the collision phase always begins after the complete detachment of the entire oceanic plate along strike, model 11 (passive margin obliquity of 0°in the presence of the microcontinent; Figure 7) shows an earlier collision between the microcontinental block and the right continental plate (Figure 7b-ii), when the tearing of subducting slab has not yet reached its terminal point in the back segment of the convergence zone (Figures 7b-i). In other words, the presence of the microcontinent leads to a synchronous continental collision and slab breakoff, as also reported in a previous study by Gün et al. (2021). Moreover, the existence of the microcontinent appears to delay slab breakoff (by ∼0.86 Myr) in the back segment compared to the front segment, which includes the microcontinent area. ...
Article
Full-text available
The horizontal propagation of slab detachment (slab tearing) is known to control lateral migration of the mountain uplift along the collisional belt. However, along‐strike differential collision due to an oblique passive margin geometry can make the topography response more complex. In this study, we employ 3D thermomechanical modeling to distinguish between the lateral migration of the mountain topography driven by slab tearing and oblique continental collision itself. In our models, slab breakoff is triggered by the transition from oceanic to continental subduction, occurring earlier on one side of the passive margin than on the other due to the initial oblique configuration. However, once slab breakoff has begun, it spreads horizontally in the form of tearing at high velocity (∼38–118 cm yr⁻¹), and associated topographic uplift also propagates with the same velocity. In contrast, the along‐strike migration of subsequent continental collision and related topographic uplift propagation is typically much slower (∼2–34 cm yr⁻¹). Similarly, the vertical magnitude of surface uplift caused by slab tearing is higher (up to 10 mm yr⁻¹) than the following collision phase (<4 mm yr⁻¹). The parametric analysis reveals that slab tearing velocity and the associated horizontal propagation of mountain uplift depends on obliquity angle and slab age, whereas the migration of collision‐induced topographic growth is controlled by the convergence velocity and obliquity angle. Finally, we show that presence of microcontinental block detached from the passive margin leads to spatial and temporal transition from horizontal to vertical slab tearing and more intense syn‐collisional mountain building.
... Despite advances in understanding the coupling between mantle convection patterns and plate motions (e.g. Zhong et al. 2007Zhong et al. , 2008Li and Zhong 2009;Yoshida andSantosh 2011, 2014;Yoshida 2016;Heron 2019;Gün et al. 2021;Langemeyer et al. 2021;Wolf and Evans 2021), the tectonic and kinematic descriptions of these geodynamic scenarios in the context of supercontinent cycles are lacking. Here, we propose new tectonic definitions for interior and exterior oceans that acknowledge the improved understanding of coupled supercontinent and convective mantle dynamics, thus allowing for the consistent identification of supercontinent formation by introversion and/or extroversion. ...
Article
Supercontinent amalgamation is described by the end-member kinematic processes of introversion - closure of interior oceans; extroversion - closure of exterior oceans; or orthoversion - amalgamation 90° from the centroid of the previous supercontinent. However, supercontinent formations are often ascribed to contradictory mechanisms; for example, Pangea has been argued to have formed by introversion from Pannotia/Gondwana, and extroversion from Rodinia. Conflicting interpretations arise partly from attempting to define oceans as interior or exterior based on paleogeography, or the age of the oceanic lithosphere relative to the time of supercontinent breakup. We define interior and exterior oceans relative to the external subduction ring, and associated accretionary orogens that surround amalgamated supercontinents. All oceans within the continental dominated cell and internal to the subduction ring are interior oceans. The exterior ocean is separated from the interior oceans by the subduction ring and bordered by external accretionary orogens. Wilson cycle tectonics dominate the interior continental cell, conversely, subduction of the exterior ocean is doubly vergent and lacks continent-continent collision. For the exterior ocean to close, the subduction ring must collapse upon itself, leading to the collision of external accretionary orogens. Employing this definition, Rodinia formed by extroversion, but all other supercontinents formed by introversion.
... Subduction of the oceanic lithosphere into the mantle exerts slab pull force on the trailing plate, the prime force that drives plate tectonic motions (Forsyth & Uyeda, 1975). In general, subduction may continue until the trailing passive margin and continental lithosphere enter the trench and some 5-15 Myr later, detachment of slab (i.e., break-off) occurs, and the subduction is terminated (Gün et al., 2021;Hafkenscheid et al., 2006;Wortel & Spakman, 2000). The termination of subduction has far-reaching geodynamic consequences, one of which is the initiation of changes in plate motions that may ignite a plate tectonic chain reaction (Gürer et al., 2022). ...
... These geological as well as seismic tomography observations suggest that the down-going oceanic slab has detached from the trailing, most likely stretched continental, Sinai Microplate. Such slab tearing along the oceanic-continental transition zone at around 200 km depth has previously been predicted by numerical models (Gün et al., 2021;van Hunen & Allen, 2011). We note that although detached at depth from the leading oceanic slab, the tomographic images suggest that the shallow subducted continental lithosphere (i.e., <200 km depth) is still being attached to the subducting oceanic lithosphere found west of Cyprus (part of the Nubian Plate). ...
Article
Full-text available
The detachment (i.e., break‐off) of down‐going subducting oceanic slabs is a major geodynamic event with far‐reaching consequences, one of which is the reduction of the slab pull force acting on the trailing plate. We investigate the motion of the Sinai Microplate where a recent (∼1 Myr ago) slab break‐off occurred along its sole converging plate boundary (Cyprian Arc) with the overriding Anatolia Microplate. Based on new bathymetric mapping, high‐resolution seismic reflection imaging, geodetic and earthquake data, we show that Sinai is actively moving in a northwest direction with respect to Nubia. Our results indicate that despite the recent slab break‐off, Sinai has and is still being pulled (or pushed) toward the overriding Anatolia Microplate. The continued convergence possibly occurs because of a persistent slab pull force, a suction force induced by the down‐going detached slab and/or by the upper mantle flow induced by the Afar Plume.
... Based on our seismic models and other geophysical evidences, we propose that the anisotropic structures observed in the SCB may demarcate a set of continental fragments that were accreted through successive orogenic events. Such continental fragments exhibit different tectonic responses to long-term evolution (e.g., Heron et al., 2023;Gün et al., 2021), and our new multiscale seismic approach presented in this study illustrates its potential to provide deep constraints that can enhance comprehension of these processes. ...
Article
Full-text available
... The geological record from the eastern Mediterranean and western Alps indicates that drifting microcontinental terranes underwent extensional deformation prior to their collision at the Tethyan subduction zone (Avigad, 1996;Gün et al., 2021;Topuz et al., 2017). It has been suggested that such pre-collisional extension may be the consequence of a "subduction pulley" (Figure 3c) where the subducted slab pulls on the lithosphere and localizes deformation at a weaker microcontinent embedded in the ocean plate (Gün et al., 2021). ...
... The geological record from the eastern Mediterranean and western Alps indicates that drifting microcontinental terranes underwent extensional deformation prior to their collision at the Tethyan subduction zone (Avigad, 1996;Gün et al., 2021;Topuz et al., 2017). It has been suggested that such pre-collisional extension may be the consequence of a "subduction pulley" (Figure 3c) where the subducted slab pulls on the lithosphere and localizes deformation at a weaker microcontinent embedded in the ocean plate (Gün et al., 2021). The syn-drift tectonics observed in the Pacific may be a plate-scale process akin to these in the Tethyan realm. ...
... For the Manihiki Plateau, it has been suggested that the extensional Suvarov and unnamed troughs and grabens reflect a change in the Pacific plate motion and slab-pull regimes (Pietsch & Uenzelmann-Neben, 2016). We agree (Gün et al., 2021). (d) Stretching factor (current ocean plateau width/initial width) evolution plots of EXP-1 to 4. Experiments show a similar plateau extension development regardless of the initial distance from trench. ...
Article
Full-text available
The paradigm of plate tectonics holds that ocean plates are rigid during drift and only experience tectonic deformation at subduction zones, but new findings from the Pacific challenge this idea. Geological and geophysical evidence from the Ontong Java, Shatsky, Hess, and Manihiki oceanic plateaux indicates that extensional deformation during plate drift is a widespread phenomenon across the Pacific plate. These anomalously thick oceanic plateaux are weaker regions of the ocean lithosphere and more prone to tectonic deformation. Numerical geodynamic models demonstrate that a slab pull force from distant subduction plate boundaries can be effectively transmitted to oceanic plateaux through strong ocean lithosphere and cause substantial extension during plate drift. Our findings reveal that a wide expanse of the Pacific has experienced syn‐drift plate tectonics linked to pull from the western Pacific subduction factory.
... Accretion and subduction zone jumps are impacted by the width and rheological structure of allochthonous terranes, the thickness of the crust, convergence rates, boundary convergence forces, mantle convection, pre-existing weak zones, rheological strength and the thermal structure of passive continental margins, and the geometry of subduction zones (e.g., Cloos, 1993;Nikolaeva et al., 2010Nikolaeva et al., , 2011Marques et al., 2013Marques et al., , 2014Buiter, 2012, 2014;Moresi et al., 2014;Vogt and Gerya, 2014;Leng and Gurnis, 2015;Wan et al., 2019;Kiss et al., 2020;Gün et al., 2021;Yan et al., 2021Yan et al., , 2022Zhong and Li, 2022). However, past studies only considered the dynamics of continental accretion (e.g., Moresi et al., 2014), the subduction initiation of the passive continental margin without the collision process (e.g., Marques et al., 2013Marques et al., , 2014, or a single phase of subduction zone jump (e.g., Yan et al., 2021). ...
Article
Full-text available
The accretion of future allochthonous terranes (e.g., microcontinents or oceanic plateaus) onto the southern margin of Asia occurred repeatedly during the evolution and closure of the Tethyan oceanic realm, but the specific geodynamic processes of this protracted convergence, successive accretion, and subduction zone initiation remain largely unknown. Here, we use numerical models to better understand the dynamics that govern multiple terrane accretions and the polarity of new subduction zone initiation. Our results show that the sediments surrounding the future terranes and the structural complexity of the overriding plate are important factors that affect accretion of multiple plates and guide subduction polarity. Wide (≥400 km) and buoyant terranes with sediments behind them and fast continental plate motions are favorable for multiple unidirectional subduction zone jumps, which are also referred to as subduction zone transference, and successive terrane-accretion events. The jumping times (∼3−20+ m.y.) are mainly determined by the convergence rates and rheology of the overriding complex plate with preceding terrane collisions, which increase with slower convergence rates and/or a greater number of preceding terrane collisions. Our work provides new insights into the key geodynamic conditions governing multiple subduction zone jumps induced by successive accretion and discusses Tethyan evolution at a macro level. More than 50 m.y. after India-Asia collision, subduction has yet to initiate along the southern Indian plate, which may be the joint result of slower plate convergence and partitioned deformation across southern Asia.
... Based on our seismic models and other geophysical evidences, we propose that the anisotropic structures observed in the SCB may demarcate a set of continental fragments that were accreted through successive orogenic events. Such continental fragments exhibit different tectonic responses to long-term evolution (e.g., Heron et al., 2023;Gün et al., 2021), and our new multiscale seismic approach presented in this study illustrates its potential to provide deep constraints that can enhance comprehension of these processes. ...
Article
Full-text available
The lithospheric architecture of the South China Block (SCB) is crucial to understanding the formation and evolution of this distinctive and highly reworked continental lithosphere with over 3 billion years of tectonic history. However, due to a lack of high‐resolution geophysical datasets, a detailed picture of the SCB lithosphere is absent, and fundamental questions regarding its formation, assembly, and subsequent reworking processes are actively debated. Assuming that unique deformation patterns due to such tectonic processes can be mapped by seismic anisotropy, we present a new crustal radially anisotropic shear‐wave velocity model along a 1500‐km seismic transect that spans the major tectonic domains of the SCB to characterize the past deformation processes. The new seismic models show significant lateral variations in seismic anisotropy and velocity, suggesting that the SCB consists of several separated (micro)continental blocks or terranes that likely have different origins and have survived the prolonged deformation history since the early formation of these continental fragments. Combining available geophysical datasets, we link individual crustal domains of distinct anisotropy to constrain the multiphase deformation processes of the SCB, including the early formation of the Proto‐Yangtze and Cathaysia Blocks, the assembly of the SCB, and the subsequent reactivation of the interior and extensive deformation that have formed the Basin‐and‐Range style tectonics in the Cathaysia Block. We suggest that relict continental fragments have played critical roles in the formation and reactivation of the SCB lithosphere.
... Determination of the Earth's internal structure, either on local or global scales, is essential in studying tectonic zones (Pysklywec et al. 2002;Heron et al. 2016;Gun et al. 2021). One of the crucial parameters related to the lithosphere (including the crust and upper mantle) is its resistance to applied load and deformation, which is quantified by flexural rigidity (see Watts 2001, and references therein). ...
Article
This study derives the spatial variation of the elastic thickness (Te) and its implications for understanding the structure, geodynamic, and seismicity of the lithosphere for the Zagros fold and thrust belt region of the Arabia-Eurasia collision zone. Te is calculated using the coherence function in the fan wavelet domain based on recent terrestrial Bouguer gravity and topography data as input signals. Utilizing the load deconvolution method and Brent's method of 1D minimization, the final Te for the survey region is estimated for each grid node of the studied area. To illustrate the mass distribution in the studied area, the subsurface loading fraction (F) is calculated simultaneously with Te in the inversion. The crust thickness and density from three different global crustal models are tested and the results obtained for these input models do not yield substantially different Te patterns. The final results are in accord with the global Te models as well as previous rheological, geodynamical, and flexural studies, however, this study establishes much more detailed regional information. The calculations yield a mean value of Te of 61 km for the Zagros, with a mean estimated error of about 5 km. The high-Te values (>70 km) are observed in the southeast of the studied area (some parts of the Sanandaj-Sirjan zone, Urumieh-Dokhtar magmatic arc and most of the Central Iranian blocks); while over most of the northwest of the studied area, the value of Te is about 58 km. The Te results are consistent with the lithospheric structure of the study area and also support the idea of the crust-mantle decoupling. Further, there is a positive and negative correlation between the surface wave velocity and surface heat flow, respectively. The mean value estimated for the internal loading friction (F) of 0.4 means in most of the studied areas we may consider that the surface loading is dominant, or at least the ratio of the surface and subsurface loading can be assumed equal. Based on earthquake distribution in the period 1900–2020, seismicity is more likely to occur in areas with a relatively low value of Te.
... After the forced subduction of a certain amount of lithosphere (e.g., Faccenna et al., 1999;Hall et al., 2003), its sinking into the asthenosphere becomes a self-sustained process, given that the negative buoyancy of the subducted lithosphere exceeds the various forces playing against subduction (e.g., Gurnis et al., 2004), such as the elastic resistance to bending and the viscous resistance of the asthenosphere (Forsyth and Uyeda, 1975;Conrad and Lithgow-Bertelloni, 2002;Ranero et al., 2003;Schellart, 2004). At this tipping point, the downgoing slab starts to pull the entire lower plate toward the trench (Spence, 1987), and an extensional state of stress can be established even at hundreds of kms from the trench (Gün et al., 2021). Extensional deformation in the lower plate associated with the inception of slab pull has been already documented hundreds of kms far from the trench (Capitanio et al., 2009;Tavani et al., 2020;Gün et al., 2021). ...
... At this tipping point, the downgoing slab starts to pull the entire lower plate toward the trench (Spence, 1987), and an extensional state of stress can be established even at hundreds of kms from the trench (Gün et al., 2021). Extensional deformation in the lower plate associated with the inception of slab pull has been already documented hundreds of kms far from the trench (Capitanio et al., 2009;Tavani et al., 2020;Gün et al., 2021). Given the central Mediterranean plate framework during the Aptian-Cenomanian interval, with coeval extension in Adria and Sirt basin and the subduction on the Neotethys to the north (Fig. 8), we infer that slab pull is a viable mechanism to explain the reviewed Aptian-Cenomanian extension. ...
... The occurrence of extension in the upper plate (Europe) at 90 Ma (Toljić et al., 2018 and references therein), and onset of extension in the lower plate (Adria and Sirt basin) at about 100 Ma as documented in this work (Fig. 9), nicely fits the slab pull scenario. Another supporting observation, coming from numerical modeling of subduction pull, is that related extension is particularly efficient in small continental fragments, whereas the oceanic lithosphere of the lower plate is essentially unaffected by extension (Gün et al., 2021). The fact that Aptian-Cenomanian extension in Adria has mostly affected continental ribbons (i.e., the carbonate platforms), and that the continental crust of both Adria and the Sirt basin have experienced extension which is not developed in the oceanic lithosphere of the Ionian Ocean in between, is in good agreement with results by Gün et al. (2021). ...
... The incipient process of extension in the crust of the LAT basement, and consequent lithospheric thinning, probably resulted in an "erosion" of the lithospheric mantle, with the lithosphere-asthenosphere boundary (LAB) rising from ∼ 142 km to ∼ 128 km during the Basin Stage. The extension of the cratonic lithosphere probably occurred passively during the collision with the surrounding terranes between 605 and 590 Ma (Lino et al., 2021;Quiroz-Valle et al., 2023), and therefore precludes pre-collisional extension by a "subduction pulley" mechanism as recently proposed for microcontinental terranes (e.g., Gün et al., 2021). On the other hand, the second period of extension seems to have been much more intense, and the thickness of the eroded (root-collapsed) lithosphere of the LAT basement resulted in a further rise of the LAB to ∼ 93 km. ...
Article
Full-text available
The Ediacaran Campo Alegre-Corupá Basin in South Brazil developed in two stages, the synorogenic passive rift (Basin Stage ∼605–590 Ma) and the post-collisional caldera volcano (Caldera Stage ∼583–577 Ma), respectively. Volcanic rocks from the Basin Stage show a bimodal compositional spectrum with dominant basalt and subordinate silicic rocks. The basaltic rocks are transitional to mildly alkaline, exhibiting Ocean Island Basalt-like (OIB-like) trace element enrichment patterns, with depletion in Nb and Ta, however, and crustal-like Sr-Nd isotopic signatures, suggesting that they were derived from low degrees (∼5%) of partial melting of an enriched lithospheric mantle source. The silicic rocks are transitional to mildly alkaline trachydacites associated with subordinate rhyolites, exhibiting trace element compositions typical of A2-type granitoids, produced by fractional crystallization of the coeval basalts in the Moho. Volcanic rocks from the Caldera Stage are constituted mainly by alkaline trachytes and rhyolites, occurring primarily as pyroclastic sequences coupled to minor effusive lava flows and domes, also exhibiting trace element compositions typical of A2-type granitoids. They are associated with subordinated effusive transitional to mildly alkaline basalts with Island Arc Basalt-like (IAB-like) trace element signatures. Compared to the Basin Stage, the basalts from the Caldera Stage result from higher degrees (∼15 %) of partial melting of possibly the same enriched lithospheric-mantle sources during the lithospheric root collapse of a cratonic terrane. The silicic rocks from the Caldera Stage are also derived from the coeval basalts by fractional crystallization in the Moho. However, an additional stage of differentiation in the upper crust is required to explain their silica-enriched compositions and eruptive styles. Results from this study support a connection between the silicic volcanic rocks from the Caldera Stage and the plutonic bodies from the nearby A-type Graciosa Province. Lu-Hf isotopes from detrital zircon suggest an Andean arc-type tectonic setting during the Paleoproterozoic (∼2,185 Ma) history of the Luis Alves Terrane (LAT) basement. This tectonic setting was responsible for the arc-like signatures of the intraplate lithospheric-derived rocks of both bimodal volcanic sequences. Crustal-like Sr-Nd-Hf isotopic characteristics result from a protracted isotope evolution of their enriched mantle sources, and each tectono-magmatic stage results from a different extensional setting, which has implications for the metacratonization of the LAT.