Revisiting orogens during the OROGEN project: tectonic maturity, a key element to understand orogenic variability

Abstract

By demonstrating that extensional inheritance plays a decisive role in the formation of orogens, recent studies have questioned the ability of a unique, complete Wilson cycle model to explain the diversity of collisional orogens. For 5 years, the OROGEN Research Project had therefore the ambition to challenge this classical Wilson cycle model. By focusing on the diffuse Africa-Europe plate boundary in the Biscay-Pyrenean-Western Mediterranean system, the project questioned the preconceived “Orogen singularity” assumption and investigated the role of divergent and convergent maturities in orogenic and post-orogenic processes. This work led us to rethink the development of collisional orogens in a genetic (or process-driven) way and to propose an updated version of the ” classical Wilson cycle”, the Wilson Cycle 2.0, and the ORO-Genic ID concept presented in this paper. The particularity of the Wilson Cycle 2.0 is to take into account the divergence and convergence maturity reached during extensional and orogenic processes in proposing different tectonic tracks associated with different ORO-Genic ID numbers. The ORO-Genic ID is composed of a letter (or track), corresponding to the maturity of divergence reached and a number corresponding to the maturity of convergence reached during the formation of the orogen. This new concept relies on the observed pre- and syn- convergent tectono- stratigraphic and magmatic record and deformation history and can be identified in using diagnostic criteria presented in this paper. It represents therefore a powerful tool that can be used to characterize the evolution and the architectural type of an orogenic system. Moreover, as a mappable concept, it can be easily used worldwide and can help us to explain differences in the style of deformation at crustal scale between orogens.

Full text

Special Issue Orogen lifecycle: learnings and perspectives from Pyrenees, Western Mediterranean and
analogues, ed. O. Lacombe, S. Tavani, A. Teixell, D. Pedreira et S. Calassou
Revisiting orogens during the OROGEN project: tectonic maturity,
a key element to understand orogenic variability
Emmanuel Masini
1,2,*
, Suzon Jammes
1
, Sylvain Calassou
3
, Olivier Vidal
2
, Isabelle Thinon
4
,
Gianreto Manatschal
5
, Sébastien Chevrot
6
, Mary Ford
7
, Frédéric Mouthereau
6
, Olivier Lacombe
8
and The Orogen Team
1
M&U SASU, Geology by Research,38360 Sassenage, France
2
ISTERRE, University of Grenoble Alpes,38000 Grenoble, France
3
TOTAL SE, R&D Department,64000 Pau, France
4
BRGM, Orléans, France
5
Universitede Strasbourg, CNRS, ITES UMR 7063, Strasbourg F-67084, France
6
GET, UMR 5563, Observatoire Midi Pyrénées, Université Paul Sabatier, CNRS, IRD, Toulouse, France
7
CRPG, Université de Lorraine, Nancy, France
8
Sorbonne Université, Institut des Sciences de la Terre de Paris (ISTeP), CNRS-INSU,75005 Paris, France
Received: 8 March 2024 / Accepted: 16 September 2024 / Publishing online: 26 November 2024
Abstract –By demonstrating that extensional inheritance plays a decisive role in the formation of orogens,
recent studies have questioned the ability of a unique, complete Wilson cycle model to explain the diversity
of collisional orogens. For 5 years, the OROGEN Research Project had therefore the ambition to challenge
this classical Wilson cycle model. By focusing on the diffuse Africa-Europe plate boundary in the Biscay-
Pyrenean-Western Mediterranean system, the project questioned the preconceived “Orogen singularity”
assumption and investigated the role of divergent and convergent maturities in orogenic and post-orogenic
processes. This work led us to rethink the development of collisional orogens in a genetic (or process-
driven) way and to propose an updated version of the ”classical Wilson cycle”, the Wilson Cycle 2.0, and the
ORO-Genic ID concept presented in this paper. The particularity of the Wilson Cycle 2.0 is to take into
account the divergence and convergence maturity reached during extensional and orogenic processes in
proposing different tectonic tracks associated with different ORO-Genic ID numbers. The ORO-Genic ID is
composed of a letter (or track), corresponding to the maturity of divergence reached and a number
corresponding to the maturity of convergence reached during the formation of the orogen. This new concept
relies on the observed pre- and syn- convergent tectono- stratigraphic and magmatic record and deformation
history and can be identified in using diagnostic criteria presented in this paper. It represents therefore a
powerful tool that can be used to characterize the evolution and the architectural type of an orogenic system.
Moreover, as a mappable concept, it can be easily used worldwide and can help us to explain differences in
the style of deformation at crustal scale between orogens.
Keywords: Wilson cycle / orogenesis / rifting inheritances / tectonic maturity / Africa-Europe plate boundary / Bay of
Biscay-Pyrenean system
Résumé –En démontrant que l’héritage extensional joue un rôle décisif dans la formation des orogènes,
des études récentes ont remis en question le cycle de Wilson et sa capacité, en tant que modèle unique, à
expliquer la diversité des orogènes collisionnels. Pendant 5 ans, le projet de recherche OROGEN s’est donc
donné pour ambition de questionner ce modèle classique du cycle de Wilson. En se concentrant sur la
frontière diffuse entre les plaques Afrique-Europe dans le système Golfe de Gascogne-Pyrénées-
Méditerranée occidentale, le projet a remis en cause l’hypothèse préconçue de la « singularité orogénique »
et a exploré le rôle de la maturité divergente et de la maturité convergente dans les processus orogéniques et
post-orogéniques. Ce travail nous a amenés à repenser le développement des orogènes collisionnels d’un
*e-mail: e.masini@mandu-geology.fr
BSGF - Earth Sciences Bulletin 2024, 195, 23
©E. Masini et al., Published by EDP Sciences 2024
https://doi.org/10.1051/bsgf/2024021
Available online at:
www.bsgf.fr
This is an Open Access article distributedunder the terms of the Creative Commons Attribution License(https://creativecommons.org/licenses/by/4.0),which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

point de vue génétique (ou axé sur les processus) et nous a amené à proposer une version actualisée du
« cycle de Wilson classique », appelée Cycle de Wilson 2.0 et le concept d’ID ORO-génique présenté dans
cet article. La particularité du Cycle de Wilson 2.0 est de prendre en compte la maturité de la divergence et la
maturité de la convergence atteinte au cours des processus d’extension et d’orogénèse, en proposant
différents parcours tectoniques associés à différents numéros d’identité ORO-génique. Le numéro d’identité
ORO-génique est composé d’une lettre (ou d’un parcours), correspondant à la maturité de la divergence
atteinte, et d’un numéro correspondant à la maturité de la convergence atteinte lors de la formation de
l’orogène. Ce nouveau concept repose sur l’enregistrement tectono-stratigraphique et magmatique avant et
pendant la phase de convergence, ainsi que sur l’histoire de la déformation observée, et peut être identifiéen
utilisant les critères diagnostiques présentés dans cet article. Il constitue donc un outil puissant pouvant être
utilisé pour caractériser l’évolution et le type architectural d’un système orogénique. De plus, en tant que
concept cartographiable, il peut être facilement utilisé dans le monde entier et nous aider à expliquer les
différences de style de déformation à l’échelle crustale entre les orogènes.
Mots clés : Cycle de Wilson / orogénèse / héritage extensif / maturité tectonique / limite de plaque Afrique-Europe /
système du Golfe de Gascogne et des Pyrénées
1 Preamble
Orogens display a large variability of size, relief,
lithotypes, along- and across-strike structures, as well as in
their tectono-stratigraphic and metamorphic records, suggest-
ing that each orogen is unique. What controls this apparent
diversity remains an open question: does it relate to a
variability in the orogenic processes at work during conver-
gence? Or does it relate to a variability in the characteristics of
the oceanic/rift system involved, which we refer to as
“divergence inheritance”or to a combination of both? The
OROGEN research project, an academic-industry joint-
venture involving more than one hundred geoscientists, was
set up to answer these questions. Over 5 years, 30 PhD and
post-doctoral projects handled by young talents, to whom this
paper is dedicated, have challenged the preconceived “orogen
singularity”assumption. The study area chosen for the project
was the diffuse Africa-Europe plate boundary in the Biscay-
Pyrenean-Western Mediterranean system because it provides a
present- day access to different evolutionary steps of a Wilson
Cycle spatially (un-shortened rift, early orogen, evolved
collisional orogen, post-orogenic rift).
Based on new seismic imaging methods, focused
multidisciplinary field studies, and innovative analytical and
simulation methods, a new observation-driven, holistic
understanding of orogenic processes has emerged. Never
conceptualized before as such, it evaluates each tectonic stage
with respect of its precursors including pre-convergence
records. Although the Biscay-Pyrenean system is one of the
best documented orogenic systems in the world, the new
approach developed in the OROGEN project has achieved a
new level in the detailed description of the architecture of this
orogenic system and in the understanding of its evolution.
The results of the OROGEN Research Project have been
published in around a hundred papers, within and outside this
special volume. The main results, concepts and interpretations
have been summarized in five review papers that build the
backbone of the special volume. They are respectively about:
(1) a geophysical passive seismic imaging techniques (Chevrot
et al., 2022); (2) the key role of pre-orogenic inheritance with a
specific focus on rift inheritance (Manatschal et al., 2021); (3)
the tectono-sedimentary record and how it can help unravel the
link between relief and basin genesis from pre- to post-
orogenic stages (Ford et al., 2022); (4) the impact of near-
versus far-field interactions on orogenesis (Mouthereau et al.,
2021); and (5) the role of the subducting slab dynamics in syn-
and post-orogenic records (Jolivet et al., 2021).
The following contribution builds on the results of the
OROGEN Research Project and on the five aforementioned
review papers. It certainly cannot compile all of the individual
outcomes of the OROGEN project, but we hereby aim to
introduce, provide examples, and discuss the concept of
“tectonic maturity”, which has emerged from extensive
discussions among the OROGEN researchers. The “tectonic
maturity”concept aims to integrate the variability of the re-,
syn- and post-orogenic settings considering that each stage of
the Wilson cycle (divergence and convergence) can continue
until its most mature evolutionary stage or can stop
prematurely if the driving forces cease. This requires us
therefore to look at a given final orogenic product as the result
of the interactions between “inheritances”and convergence-
induced processes. This approach contrasts with the traditional
view, which considers that an orogen is primarily controlled by
convergence-induced processes and a partially inherited
mechanical stratigraphic template. In this view, each orogen
is unique and cannot be understood in a genetic way and time-
space geological prediction strictly relies on a regional expertise.
2 Introduction
In the 1960s, scientists started to understand that orogens
are part of the plate tectonic process that became known as the
Wilson Cycle (Wilson, 1966;Dewey and Bird, 1970). The
Wilson Cycle was quickly accepted, and rapidly became a
paradigm and a starting point in plate tectonic reconstructions.
The main assumption was that orogens went through the same
life-cycle including rifting, seafloor spreading, oceanic
subduction, continental collision and post-orogenic collapse
and that diversity amongst orogens resulted from unique
geological processes and different boundary conditions rather
than from differences in their life-cycle. Recent studies in the
Pyrenees and the Alps, both belonging to the best studied
orogens world-wide, have raised questions about the role of
pre-orogenic structures during early collision, formation of
Page 2 of 21
E. Masini et al.: BSGF 2024, 195, 23

internal parts of these orogens and the control that an orogen
segment can have on adjacent segments as a boundary
condition. In both alpine and pyrenean orogens, the
observations of preserved remnants of distal margins within
their inner (internal) units suggest that some of the present-day
complexities may be inherited from the pre-orogenic rifting
phase. More generally, Chenin et al. (2017) and Vasey et al.
(2024), suggest that orogens resulting from the closure of
narrow oceans and essentially controlled by crustal-deforma-
tion processes (Vlaar and Cloetingh, 1984;Pognante et al.,
1986;Rosenbaum and Lister, 2005;Mohn et al., 2010) differ
from orogens resulting from the closure of wide oceans and
subduction-induced processes (Uyeda, 1981;Willett et al.,
1993;Ernst, 2005;Handy et al., 2010). By demonstrating that
extensional inheritance plays a decisive role in the formation of
orogens, these results pave the way to new interpretations of
the internal parts of collisional orogens and generate a new
genetic way (meaning process-driven way in this paper) to
classify them as a function of divergent and convergent
maturities. This in turn challenges the ability of a unique,
complete Wilson cycle model to explain the diversity of
collisional orogens.
No study prior to the OROGEN project has explored in
such a systematic way the architecture of a wide area
preserving different evolutionary steps of the Wilson Cycle, as
observed along the diffuse Africa-Europe plate boundary in the
Biscay-Pyrenean-Western Mediterranean system. The work of
more than one hundred Earth scientists involved in the project
did not only produce new seismic images of the subsurface,
new mapping of critical structures and new analytical data,
including chronological and dynamic models, but also a new
observation-driven, holistic understanding of orogenic pro-
cesses, from the pre- to the post-orogenic stage. The OROGEN
community developed the new concept of “tectonic maturity”,
which can integrate so-called immature extensional systems
(i.e., extensional systems devoid of wide oceanic domains or
hyperextended distal margins) in a Wilson Cycle and thus
proposes an updated version of the Wilson Cycle. As it is, the
classical Wilson cycle represents only orogen resulting of the
closure of wide oceanic domain and subsequent collision of
margins. On the contrary, the updated model, referred to as
Wilson Cycle 2.0, has been developed to integrate the different
degrees of maturity that can be reached in magma-poor
divergent settings and how these divergence templates interact
with convergence. The conceptual model, as well as examples
and applications are presented in Sections 3 and 4.Asa
disclaimer, it is important to note that the concept has been
developed based on observation made in Western European
Orogens built on failed rift and/or narrow oceans. Its
applicability to Himalayan and Andean systems remains to
be investigated.
3 The concept of tectonic maturity and the
Wilson Cycle 2.0
The Wilson Cycle 2.0 (WC 2.0), like the traditional
version, is a representation of successive divergent and
convergent tectonic stages that can be reached through time as
stable continents diverge and converge (see Fig. 1). However,
the WC 2.0, allows, in contrast to the original version, for
possible “shortcuts”that depend on the tectonic maturity
reached during divergence. Indeed, the WC 2.0’s main
assumption is that the fate of convergent systems depends
partly on the degree of maturity reached during divergence. To
integrate possible shortcuts in the WC 2.0, we associate
divergent maturity levels (A, B, C, or D) to convergent
maturity levels (1, 2, 3 or 4) within an orogenic life-cycle,
referred to as tectonic tracks. For clarity, the different possible
tectonic tracks (A, B, C and D) are fully represented in
supplementary material (see Figures A1,A2,A3 and A4). Note
that “impossible domains”, indicated in grey in Fig. 1 and
supplementary material, correspond to the shortcuts in the
track, which depend on the final maturity reached during
divergence (i.e. function of when continents stop separating).
For example, without the formation of a wide ocean, no mature
oceanic subduction associated with a volcanic arc can form as
it cannot give birth to a subducting plate with sufficient
negative buoyancy (Chenin et al., 2017). A key point in the
new approach is to be able to define the degree of divergent and
convergent maturity reached in a track, based on first order
geological observations and clear diagnostic criteria (see
Tabs. 1 and 2). Rigorous application of the diagnostic criteria
allows the definition of the so-called Orogenic-Genetic
Identification number (ORO-Genic ID). This code corresponds
to a letter and a number corresponding to the maximum
maturity reached during a track (for instance D1 for a full,
classical Wilson cycle). The ORO-Genic ID can express the
evolution of an orogenic system but can also be used to map
domains that result from different tracks (see Sect. 4).
It is important to note that some ORO-Genic IDs do not
exist as shown with the grey areas in Figure 1. Examples are
A1, A2, and A3 along track A (Fig. A1), or B1 and B2 along
track B (Fig. A2). The main reason is that the formation of an
oceanic subduction system requires, to initiate and be
sustainable, a wide oceanic domain. In the case of track C
(immature, narrow oceanic domain, Fig. A3), a subduction can
initiate (ORO-Genic ID C1), however, continents start to
interact (stage 3) before the negative buoyancy of the slab
reaches the critical value leading to a mature, self-sustained
subduction (slab-pull efficient enough to sustain the subduc-
tion) (Chenin et al., 2017). Such systems will therefore take a
short cut and evolve, if not abandoned, to early orogenesis
(ORO-Genic ID C3) and collision (ORO-Genic ID C4)
without creating a mature subduction (impossible ORO-Genic
ID C2) (Fig. 1).
Defining the respective degree of divergent and convergent
maturity and therefore the ORO-Genic ID requires distinctive
and clear criteria, based on rigorous geological or geophysical
observations, and can result in a mapping approach as shown in
Section 4. Similar approaches have been used in the Alps and
are described in McCarthy et al. (2021). In the following
paragraphs we define the diagnostic criteria and the approach
used to define divergent and convergent maturity stages.
3.1 Divergent maturity
In the WC 2.0, we define 4 stages of increasing divergent
maturity that can be characterized as follow (see Tab. 1):
–Early Rift (A): This stage shows only local and very limited
crustal thinning and extension (ß <1.5), with top and base
Page 3 of 21
E. Masini et al.: BSGF 2024, 195, 23

Fig. 1. On the right : Wilson cycle updated representing the 4 maturity stages of divergence (A, B, C and D) and the 4 maturity stages of
convergence (1, 2, 3 and 4). Both the divergent and convergent cycle are predated and follow by pre and post deformation phases (i.e. stable
continent and inactive ocean basin). In the case of the end of convergence, different post-convergent scenarios are possible depending of the
maturity stage of the convergence. Those scenarios are illustrated on the left side of the figure.
Page 4 of 21
E. Masini et al.: BSGF 2024, 195, 23

Table 1. The diagnostic criteria summarizing the key observations that are characteristics of each maturity stage of divergence.
(1) Mc Kenzie (1978); (2) Stein and stein (1992)
Page 5 of 21
E. Masini et al.: BSGF 2024, 195, 23

Table 2. The diagnostic criteria summarizing the key observations that are characteristics of each maturity stage of convergence.
Page 6 of 21
E. Masini et al.: BSGF 2024, 195, 23

crust remaining tabular at a crustal scale. Rift basins are
high-angle normal fault controlled (limited crustal-scale
subsidence due to crustal thinning), distributed and often
later- ally disconnected (distributed strain). Faults are high-
angle and sole out at mid-crustal ductile levels. Syn-rift
sediments can either show high thickness and/or facies
variations over short distances (fault- controlled), whereas
post-rift sediments show, over wide areas, little accommo-
dation (km) and limited regional thermal subsidence.
–Hyperextended rift (B): This stage is characterized by a
proximal domain where the crust is weakly extended
(similar to the rift domain formed in A) and a distal
hyperextended crust (<10 km thick, ß >2) with deep, wide
and long segmented basins. The proximal and distal
domains are limited by a crustal necking zone where the
crust tapers across variable distances. Extension is
accommodated by long-offset normal faults / detachment
faults that first thin the crust (necking faults) and then
exhume the mantle underneath a progressively embrittled,
hydrated and tapering continental crust. This structural
style reflects strain localization rifting by comparison with
early rifting and efficiently forms horizontal space by
exhuming new surfaces. Mantle-decoupled hyper-exten-
sion ultimately leads to exhumation of lower crust beneath
supra-detachment basins whereas mantle-coupled hyper-
extension leads to juxtaposition of sediments with mantle
rocks. As faults are long-offset (high strain) and cross the
entire crust, fluids efficiently circulate leading to hydrated
crustal and mantle rocks (i.e. serpentinization). Note that
magmatic processes also interact with rifting and can range
between N-MORB and alkaline. Syn-rift accommodation
space is maximum within a wide and highly subsiding rift
basin. Syn-rift sediments can therefore be up to 10 km-
thick for fully-filled basins but generally show deepening
depositional environments to abyssal environments if syn-
rift sedimentation rates are low. Post-rift sediments are also
generally deep-marine but can be in extreme cases (e.g.
front of large deltas) shallow marine/continental but with
kilometric thicknesses.
–Narrow Oceanic basin (C): This stage includes, in addition to
the aforementioned characteristics, an OCT (Oceanic-
Continent Transition) domain (with exhumed mantle and/
or magmatic additions ranging from alkaline to T-MOR
compositions) and an embryonic oceanic lithosphere made
of exhumed subcontinental mantle. We consider an oceanic
system as “narrow”or “immature”when it is too narrow and
not dense enough (density being composition and/or age-
dependent) to create a slab able to generate and sustain a
subduction by negative buoyancy (i.e. slab pull) only.
–Wide Ocean (D): This stage is related to the formation of a
wide oceanic lithosphere between diverging continents.
Mantle and magmatic rocks are genetically linked and
expected to be N-MORB except if a plume is present. We
consider the ocean as “wide”or “mature”if it can generate
a sustainable (i.e., slab-pull controlled) subduction. Note
that Chenin et al. (2017) proposed that oceans wider than
300 km can be considered as “wide oceans”. However, as
subduction is a consequence of the negative buoyancy of a
slab, the age and the composition of the slab should be also
considered at the onset of convergence.
While the divergent maturity stages A to D are easy to
define at present day rifted margins using seismic data (see rift-
domain concept of Tugend et al. (2014)), in orogenic systems
their recognition is more difficult and based mainly on
diagnostic criteria (see 1). A major challenge in orogenic
systems is also that parts of the divergent system and especially
wide oceans have been subducted, and, therefore, must be
recognized by indirect criteria, such as the occurrence of arc
signatures or by tomographic mapping of detached slabs in the
underlying mantle. In contrast, distal parts of magma-poor
margins, including the serpentinized mantle, either commonly
escape subduction or are subducted and then exhumed and
emplaced as high-pressure rocks in internal units of collisional
orogens. Magma-rich margins are likely to be subducted and
therefore not to be present in collisional orogens (see Gómez-
Romeu et al. (2023);Ganade et al. (2023)).
In a more applied way, and as explained previously, in the
ORO-Genic ID (see Fig. 1 and Tab. 1), it is important to
identify the highest stage of divergent maturity reached prior to
convergence, which can be done by answering, in a
consecutive way, the following three questions.
Q
D1
: Did rifting stop before necking, i.e., before thinning
the crust to less than 20 km thickness?
Q
D2
: Did rifting result in crustal separation and formation
of a proto-oceanic domain?
Q
D3
: Did seafloor spreading result in a wide/mature
oceanic domain that could give birth to a mature subduction?
A“yes”to QD1 points to stage A (Early Rift), while a “no”to
QD1 and QD2 is characteristic of stage B (Hyperextended Rift);
a“yes”to QD2 and a “no”to QD3 points to stage C (Narrow
Oceanic basin), and finally, a “yes”to QD3 is compatible with
stage D (Wide Ocean). Answering QD1, QD2 and QD3 requires
the use of diagnosticcriteria listed in Table 1. An example of how
toapplythis newconceptispresentedin Section 4 usingthe focus
area of the OROGEN project.
3.2 Convergent maturity
In the WC 2.0, we define 4 stages of convergent maturity
labelled as 1, 2, 3 and 4 in Figure 1 that can be characterized as
follow:
–Immature Subduction (1): In this stage, most of the
deformation is localized along the subducting slab made
either of mature or proto-oceanic lithosphere. Structurally,
this results in thin-skinned dominated deformation in the
accretionary wedge with limited deformation involving
the basement in the retro-wedge. Subduction-related
magmatism may be in an embryonic stage or simply
absent. If far-field driven convergence stops, the gravity-
driven forces (slab-pull) are as yet insufficient to counteract
the buoyancy of the slab and therefore subduction fails and
freezes (see dead subduction system in Fig. 1).
–Mature Subduction (2): In this convergence stage,
deformation is still localized along the subducting slab
and results mostly in thin-skinned deformation in the
accretionary wedge mostly involving oceanic sediments.
Calc-alkaline magmatism is expected in the upper plate
forming a mature arc, but can be inhibited by the magma-
poor nature of the oceanic lithosphere (McCarthy et al.,
2018). If far-field driven convergence stops, the negative
Page 7 of 21
E. Masini et al.: BSGF 2024, 195, 23

buoyancy of the subducted oceanic slab (slab-pull) remains
dominant. As a result, the subduction cannot stop, leading
to the retreat of the slab and the development of a back-arc
basin in the upper plate (see back-arc system in post
convergence situation in Fig. 1). Note that a decrease in
plate convergence can lead to a similar record.
–Early Orogenesis (3): In this stage, most of the deformation
is concentrated in the inverting hyperextended domain.
Reactivation occurs in the presence of flysch type (deep-
water syn-orogenic turbidite) sedimentation and if previ-
ously present, arc-type magmatic activity stops in the upper
plate as continental material enters the subduction zone (so
called “continental subduction”). The front of thick-
skinned deformation (or deformation involving the
basement) remains in between the necking lines (see
Fig. 2b) implying that at this stage only former distal
(hyperextended) parts of the rifted margin are consumed
and rift/post-rift sedimentation deforms within the accre-
tionary wedge. The distal parts of the down going crustal
taper in the lower plate can reach HP to UHP conditions
(>15 kbars) prior to being exhumed back in the subduction
channel, leading to a prograde-retrograde metamorphic
record. If convergence stops, an early orogen involving
only inversion of the hyperextended domain is formed (see
early orogen system in post convergence situation in
Fig. 1). If this early orogenesis stage follows a mature
subduction (track D, see Fig. A4), the hanging wall
contains former arc material. In addition, the underthrust-
ing of the hyperextended domain made of low-density
crustal material increases slab buoyancy and plays against
the slab-pull force. The subduction can stop, and the slab
can detach (e.g., slab breakoff of Davies and von
Blanckenburg (1995)). Alternatively, if early orogenesis
follows an immature subduction (track C, see Fig. A3), the
hanging wall is formed by the former conjugate margin
without former arc activity. The slab can reach high-
pressure conditions but may not be exhumed. Slab breakoff
is not necessarily expected. The slab is therefore preserved
at depth and visible in tomographic data section which can
explain the lack of exhumation of high-pressure rocks.
–Mature Collision or Inverted Basin (4): In this convergence
stage, deformation migrates out over previously weakly
thinned crust (crust >20 km thick) and propagates outside
the necking domain in the pro-wedge side. Thick-skinned
structural shortcuts are formed and the orogen develops
into a double- vergent geometry (Fig. 2c). Two contrasting
cases can be envisaged. Either a former Early Rift (stage A)
is inverted, resulting in an inverted basin (ORO-Genic ID
A1, see Fig. A1), a process that is local and involves
limited shortening, often triggered by far field stresses to
deform thick crust. A second, and very different case, is the
formation of a collisional belt that deforms crust that
followed tracks B, C and D. During the collision stage, the
classical fold-and-thrust belts form, including thin- and
thick-skinned nappe-stacking. Crustal thickening, resulting
in the formation of isostatically induced high topography
often between external (former proximal) and internal
(former distal) domains at the location of the former
necking zone. The nature of the internal parts of the orogen
will strongly differ depending on the maturity reached
during the divergent stage (see Figs. A2,A3 and A4).
While arc material can be expected for track D, ophiolites
including subcontinental mantle, remnants of crustal
blocks including pre-rift lower crustal rocks, associated
with deep water sediments can be expected for track B
and C, with in addition T-MOR and alkaline magmas for
track C, to more classical N-MORB for track D. Outside
the necking zones, in the former proximal margin above a
>20 km thick crust, flexural foreland basins are formed
due to the increasing load of the forming collisional belt.
Pro and retro-foreland basins are filled by molasse type
(syn-orogenic marine and continental) sedimentary
sequences. The nature of this domain seems to be
independent of the previous convergent history (see
Fig. 2c) and is controlled more by an interplay between
an inherited mechanical stratigraphy (specific to local pre-
rift geological record and therefore not predictable
genetically), erosion and sedimentation. The vergence of
the belt has also consequences for the respective dynamics
of pro- and retro-foreland basins. The prowedge accom-
modates high shortening by horizontal propagation of
deformation (lower plate), whereas the retrowedge
accommodates considerably less shortening above the
orogenic buttress (less propagational, see details in Ford
et al. (2022) and references therein). When convergence
stops in a mature collisional orogen, orogenic collapse and
related extension can occur, being-favored by high
gravitational potential energy (GPE), isostatic disequili-
bration and the presence of an orogenic root. This process
does not occur in less mature orogens (see post-
convergence situation in Fig. 1).
As in the divergent case, answering, in a consecutive way,
questions Q
C1
and Q
C2
, formulated below, can define the
ORO-Genic ID (see Fig. 1 and Tab. 2) of the system.
Q
C1
: Did an oceanic subduction/slab form and if yes, did it
reach steady state?
Q
C2
: Does the front of the thick-skinned deformation go
beyond the necking line?
If the answer to Q
C1
is “yes”convergent stage 2 was
reached, but if the answer is “no”only convergent stage 1 was
reached. If the answer to Q
C2
is “no”the convergent stage 3
was reached, and if the answer is “yes”, stage 4 was attained.
However, in most cases convergent stages can be modified by
the so- called post-convergence stages that can include a dead
subduction, long-lasting arc activity, back-arc extension or
orogenic collapse. These post-convergence stages are not
included in the ORO-Genic ID but are indicated with the
symbol * and shown in the WC 2.0 in Figure 1.
4 The oro-genic id approach applied to the
Biscay/Pyrenean system
The along strike variation of the orogenic architecture in
the Biscay/Pyrenean system, with a well- preserved divergent
stage in the Bay of Biscay and a dominant convergent overprint
in the Pyrenees, makes this system an ideal example to
illustrate the ORO-Genic ID approach and to exemplify
different tracks within the WC 2.0. In the past, the highly
variable orogenic architecture along strike, reflected by
different structures, nature and compositions of basements
rocks, tectono-stratigraphic and metamorphic records resulted
Page 8 of 21
E. Masini et al.: BSGF 2024, 195, 23

Fig. 2. Schematic representation of a rifted margin and two stages of convergent maturity highlighting the position of the front of the thick-
skinned deformation with respect to the former necking line. a) The proximal, distal and oceanic domains are illustrated as well as the main
structural limits between them (necking line, Outer limit of Continental crust (OLCC) and landward limit of Oceanic Crust (Laloc). b) In an early
Orogenesis convergent stage the front of the thick-skinned deformation doesn’t no traverse the former necking line. c) In a mature collision
stage, the front of the thick-skinned deformation traverses the former necking line thus involving formerly un-thinned continental crust.
Page 9 of 21
E. Masini et al.: BSGF 2024, 195, 23

in many different, and partly conflicting interpretations of the
Biscay/Pyrenean system. One of the major outcomes of the
OROGEN project was to demonstrate that the complexity is
not only the result of convergence, but also results from the
interplay between inherited divergent maturity and the
subsequent convergent overprint (Fig. 3). Based on new data
and observations acquired during the OROGEN project, it was
possible to answer the ORO-Genic questions (Q
D1
,Q
D2
,Q
D3
,
Q
C1
and Q
C2
) using the diagnostic criteria listed in Tables 1
and 2and to map the maturity levels of the divergent and
convergent stages reached in the Biscay/Pyrenean domain
(Fig. 4). Key information on which the study is based can be
found in the Orogen Headpapers (Chevrot et al. (2022);Jolivet
et al. (2021);Ford et al. (2022);Mouthereau et al. (2021);
Manatschal et al. (2021) and references therein compiling
results of the OROGEN project). They are: 1) the new
tomographic images that provide information on the existence
or non-existence of a slab along strike (see Q
C1a
andQ
C1b
in
Tab. 2), 2) the mapping of necking zones, the front of the thick-
skinned deformation and the syn-rift depocenters across the
Biscay-Pyrenean system (see Q
D1
in Tab. 1 and Q
C2
in Tab. 2),
3) the study of the syn- and post-tectonic depositional
environments and the nature of the exhumed mantle and
magmatic rocks (see Q
D1
in Tab. 1), and 4) new plate kinematic
models to test the width of the paleo-Biscay/Pyrenean domain
prior to convergence (Q
D3
in Tab. 1). Based on these new
results it was possible to propose new crustal scale sections
(Fig. 3) and maps (Fig. 4) that show the life-cycle track (from
A to C) and ORO-Genic ID of different domains in the Biscay-
Pyrenean system. It is interesting to note that all track types can
be found regionally as a non-reactivated mature ocean can be
identified in the Iberian Atlantic margin outside the Biscay-
Pyrenees area. This shows that the maturity of divergence can
change laterally (more mature and wider in the west vs. less
Fig. 3. Example of ORO-Genic ID assigned along three cross sections located in the Bay of Biscay/Pyrenean system. i) C1* : The Northern
Iberian margin (modified from Tugend et al. (2014)), ii) B3 : The Basque Cantabrian Basin (modified from Miró et al. (2021)) iii) B4 : The
Western Pyrenees (modified from Teixell et al. (2016);Gómez-Romeu et al. (2019)). See Figure 4 for location.
Page 10 of 21
E. Masini et al.: BSGF 2024, 195, 23

mature and narrower in the east). In the following we present
some examples, by going from West to East through the
Biscay/Pyrenean system.
–The North Iberian margin (Fig. 3a): The North Iberian
margin was interpreted as an accretionary prism related to
the formation of an oceanic subduction (Boillot et al.,
1984;Alvarez-Marron et al., 1997). However, seismic
refraction results refuted this hypothesis (Fernéndez-Viejo
et al., 1998;Ruiz Fernàndez, 2007). New studies in the
OROGEN project (Cadenas et al., 2020;Miró et al., 2021)
interpreted this domain as a former hyperextended domain
that has been reactivated during convergence leading to the
underthrusting of the domain by exhumed serpentinized
mantle. When convergence stopped, the gravity-driven
forces (slab-pull) were too low to counteract the buoyancy
of the slab. Therefore, subduction stopped naturally
resulting in a dead subduction system. In terms of maturity,
the divergence reached the level of maturity C (Narrow
Ocean, see Fig. 4a and Fig. A3) and the level 1 during
convergence (Fig. 1). The ORO-Genic ID of the northern
Iberian margin is therefore C1* (Figs. 3a and 4). The
asterisk (*) indicates that the system now forms a dead
subduction. It is important to note that thick-skinned
deformation is recorded within the Cantabrian mountains
located in the south- east of the section but this is not
related to the subduction but corresponds to a lateral border
effect of the Basque Cantabrian belt (BCB) discussed
below (see also Miró et al., 2022). The 3D implications will
be further explored below.
Fig. 4. Map of the Bay of Biscay and Pyrenean area representing: (a) the maturity of the divergence reached in the rift domains preserved in the
Bay of Biscay and in onshore fossil analogues. (b) The maturity of the convergence of the orogens present in the area. The location of the sections
presented in figure 3 is depicted in red and ORO-Genic IDs are indicated in blue.
Page 11 of 21
E. Masini et al.: BSGF 2024, 195, 23

–The Basque Cantabrian belt (Fig. 3b): The Basque Cantabrian
Belt is a good example of the Track B (Fig. A2) as it results
from the shortening of an aborted hyperextended rift where
mantle rocks have been exhumed (see Fig. 4a)(Miró et al.,
2021;Ducoux et al., 2019). During convergence, the
deformation remained restricted to the former rift basin, as
a thin-skinned belt with no evidence of thick-skinned
structural shortcuts (see Fig. 2b) in the pro-wedge and a
limited amount of crustal thickening in the pro and the retro-
wedge. These characteristics explain why this belt is often
referred to as the ”Basque Cantabrian Basin”as it still
preserves its rift evolution. In map view (Fig. 4b), we can
observe that only the front of the thin-skinned deformation
goes over the necking line (see Fig. 2 for explanation). For
these reasons, we can establish that within the Basque
Cantabrian belt the convergence was fossilized at the early
orogenesis maturity stage and is characteristic of a B3 ORO-
Genic ID (Figs. 3b and 4).
–The Western Pyrenees (Fig. 3c): The Western Pyrenees is
another example of the Track B (Fig. A2) as it results from
the shortening of an aborted hyperextended rift where
mantle rocks have been exhumed (see Fig. 4a)(Jammes
et al., 2009;Lagabrielle et al., 2010;Lagabrielle and
Bodinier, 2008;Lescoutre et al., 2019;Masini et al., 2014;
Saspiturry et al., 2019). But in contrast to the BCB, in the
western Pyrenees the thick-skinned deformation clearly
propagated beyond the former necking line (see Fig. 2c and
Fig. 4b). We can therefore determine that in the Pyrenees
the convergence reached the mature collision stage (ORO-
Genic ID B4, Fig. 3c). From B3 to B4, the Pyrenean-
Cantabrian transition is a good example where the ”ORO-
Genic ID”changes laterally due to a change of convergent
maturity.
–The Cameros basin (Fig. 4): Geological observations from
the Cameros basin located in the Central Iberian range
demonstrate that this basin is a former hyperextended basin
(life-cycle track B, Fig. A2)filled with 8 km of
syn-rift sediments (Casas-Sainz and Gil-Imaz, 1998;
García-Lasanta et al., 2017) affected by Late Cretaceous
to Miocene shortening (Del Rio et al., 2009;Rat et al.,
2019) mostly taken up by the Cameros northern thrust front
(Salas et al., 2001). Therefore, in a map view (Fig. 4b), we
can observe that the front of the thick-skinned deformation
corresponds to the former necking line and can conclude
that the system didn’t reach the mature collision stage. For
this reason, this system is identified as another example of
the B3 ORO-Genic ID.
–The Central system and the southern part of Iberian chain
(Fig. 4): The Central system and southern part of
Iberian chain correspond to inverted intra-continental
rift systems (Casas-Sainz and Gil-Imaz, 1998;Omodeo
Salè et al., 2014;Platt, 1990;Rat et al., 2019)
corresponding to the ORO-Genic ID A4. The geological
observations (narrowness, apparent absence of deep-
water sediments, hyperextension and exhumed mantle or
oceanic material) are indeed characteristic of an
immature rifted domain (divergent maturity A,
Fig. A1) affected by an intra-crustal decollement
responsible for the crustal thickening characteristic of
collisional deformation and formation of an inverted
basin (convergent maturity 4).
5 Discussion
5.1 Is the ORO-Genic ID concept applicable to other
orogens?
Orogens are complex systems resulting from a long and
polyphase evolution involving a number of processes and
displaying a large variability of structures. The OROGEN
project illustrates that the observed complexity not only results
from orogenic processes but can also be related to the
variability of the precursor record of divergence and its
implications for the subsequent convergent phases. The ORO-
Genic ID concept presented here is an attempt to integrate, in a
simple way, the importance of inheritance by introducing the
concept of tectonic maturity. The main pillar of this new
concept is the observation driven, holistic approach based on
diagnostic criteria to identify the main tectonic stages recorded
within an orogenic system during its tectonic lifecycle. This
adapted Wilson Cycle W2.0 reflects decades of geological
research both at sea and onland (see Tabs. 1 and 2). In the
Wilson Cycle 2.0 shown in Figure 1, the full range of evolution
tracks, can be characterized by answering specific questions
(see ORO-Genic questions in Tabs. 1 and 2).
It is beyond the scope of this paper to solve each existing
debate on orogenic ”singularities”such as those related to
exhumation of (ultra)high pressure rocks, the driving processes
of subduction dynamics and all inheritances that can impact the
pre-orogenic template (occurrence of micro-continents, com-
position, post-rift thermal relaxation time and age, magma/
sediment budget of both rifted margins and oceanic litho-
spheres, transform margins/fault zones, hot spots...). We can
however propose a new level of understanding of the evolution
of orogenic systems by relating orogenic variabilities to tec-
tonic maturity that can be understood genetically. In Section 4,
we illustrate how the ORO-Genic ID concept can be applied to
the Biscay-Pyrenean system, where new seismic imaging
methods, focused field studies, and innovative analytical and
simulation methods provided unique data coverage. The
question remains however, if this concept can be applied to
other orogenic systems.
The West European system along the diffuse Africa-
Europe plate boundary in Western Europe and northern Africa
is another complex orogenic system with along strike
variations in orogenic architecture. This system accommodat-
ed plate convergence from the late Cretaceous onwards leading
to the formation of strikingly different orogenic branches
(Macchiavelli et al., 2017;Angrand et al., 2018,2020;Frasca
et al., 2021;Jolivet et al., 2021;Angrand and Mouthereau,
2021;Mouthereau et al., 2021) including the Biscay/Pyrenean
system, the Central system and the Iberian chain discussed be-
fore, and the Betic/Rif, Tell and Atlas systems, the Apennines
and the Alpine system sensu stricto. On the southern edge of
the system, for example, the High Atlas belt is an intra-
continental belt that presents similarities with the Central
system of Iberia and the southern part of the Iberian chain, i.e.,
half grabens with limited accommodation space and intra-
continental decollements (Beauchamp et al.1999;Frizon de
Lamotte et al., 2008;Giese and Jacobshagen, 1992;Leprêtre
et al., 2018;Teixell et al., 2003). It can therefore be described
with the ORO-Genic ID A4, corresponding to an inverted rift
basin system.
Page 12 of 21
E. Masini et al.: BSGF 2024, 195, 23

In the eastern edge of the West European system, most of
the Alpine system reached the mature collision stage as
observed in the Pyrenean belt. However, to understand
differences between the Alps and the Pyrenees, it is important
to acknowledge that both systems belong to different life-cycle
tracks. In the Pyrenees only mantle rocks were exhumed
during extension (Track B, hyperextended basin, Fig. A2) and
true break up to form oceanic crust did not occur, while both
narrow and wide oceanic basins developed in the Alpine
system (Lemoine et al., 1987;Handy et al., 2010;Picazo et al.,
2016). The Alpine system belongs therefore to the life-cycle
track C or D (Figs. A3 and A4) and its ORO- Genic IDs vary
from C4 to D4 which contrasts with the B4 of the Pyrenees.
Differences between the two orogenic systems are therefore in
part the result of the different maturity level reached during
divergence.
Similarly, in the Betic-Rif belt, the presence of exhumed
mantle domains and MORB-bearing ophiolitic mélanges
(Gimeno-Vives et al., 2019;Pedrera et al., 2020;Puga
et al., 2011) strongly sup- ports the existence of a narrow or
wide oceanic domain (Track C or D, Figs. A3 and A4). A key
indication comes from the occurrence of the Alboran slab
imaged by tomographic data (Calvert et al., 2000;Villaseñor
et al., 2015;Bezada et al., 2013), created by the Miocene
opening of the Alboran sea and followed by subduction and
slab break-off implying the consumed ocean was wide enough
to generate a mature subduction (track D, Fig. A4). In terms of
convergence, most of the deformation is concentrated in the
inverted rift basin and the front of the thick-skinned
deformation does not affect domains beyond of the necking
line (see Fig. 2b) implying that the ORO-Genic ID of the Betic
belt is D3.
The formation of the Gulf of Lion/Tyrrhenian/Apennine
system results from the retreat of the Mediterranean steady-
state subduction (Jolivet et al., 2020;Séranne et al., 2021). The
formation of this back-arc system suggests the existence of a
wide oceanic domain (i.e., divergent maturity D, Fig. A4).
Convergence stopped after the formation of the mature
subduction. The corresponding ORO-Genic ID is therefore
D2* with the asterisk (*) to indicate that the system was
affected by post-convergence deformation. All those examples
demonstrate that the ORO-Genic ID is a powerful tool
allowing to map orogenic systems with different evolutions in
an efficient way. Linking key geological characteristics (e.g.
preserved rift, occurrence of”obducted crust”, the tectono-
stratigraphic-magmatic-metamorphic and structural records)
to an Orogenic ID may also be meaningful to determine what
process (and especially which inherited divergent template)
could control which “singularity”. Moving to economic
impacts, we believe this approach may be a key tool to
identify orogenic belts for a given targeted resource.
5.2 Consumable domain versus accretable domain
A key in understanding convergent systems is the
buoyancy of the rift domains that become involved in
orogenesis. While domains with negative buoyancy (e.g.,
oceanic lithosphere) can be fully subducted and consumed,
those with positive buoyancy (e.g., proximal margin domains)
cannot be easily subducted and will be accreted to form thick
orogenic crust (Lacombe and Bellahsen, 2016)(Fig. 2). The
fate of distal margin domains is more complex and first
depends on the occurrence and location of decoupling levels
that are mostly a function of crustal composition (Miró et al.,
2021;Gomez-Romeu et al., 2023) and temperature (i.e. age of
lithosphere and sedimentary burial). Magma-rich margins, for
instance, are assumed to be consumed, as supported by
modelling results (Ganade et al. 2023). In this case, the main
convergent decollement is within the post-rift sedimentary
cover leading to the formation of a thin-skinned accretionary
wedge without syn- or pre-rift sediments (Gomez-Romeu
et al., 2023). In contrast, hyperextended magma-poor margins
overlying exhumed mantle can either be directly accreted
when the main decollement is within or below the thinned crust
(brittle-ductile transition, base of serpentinized mantle), or first
subducted and then exhumed in the early orogen as (ultra)high
pressure rocks (Ganade et al. 2023). Thus, assessing the pre-
orogenic divergent maturity is a key to determining the nature
and width of the consumable/accretable domains that are
involved in the convergence process (see Fig. 2a). In case of an
early rift, the consumable domain is zero, resulting in an intra-
continental thick-skinned dominated inverted basin with direct
crustal thickening (ORO-Genic ID A4 Fig. 1). In the case of
hyperextended rifts, the consumable domain is limited,
implying that after being consumed during early Orogenesis
(ORO-Genic ID B3 in Fig. 1), shortening during collision will
be accommodated by thick-skinned structural shortcuts and
nappe-stacking affecting the necking zone and the proximal
margin (ORO-Genic ID B4 in Fig. 1). During collision, local
rift inheritances plays a limited role (inversion of half-grabens)
whereas the role of regional mechanical inheritances
(compositional and thermal) and the role of the feedback
loop between relief creation, erosion, transfer and sedimenta-
tion (for more details, see the Source to Sink project vade-
mecum (Castelltort et al., 2023) become predominant. In the
case of a narrow or wide ocean, the oceanic domain constitutes
the main part of the consumable domain. However, if the
oceanic system is narrow, the future slab will not be able to
generate a sustainable slab-pull force to control subduction.
Early orogenesis initiates when the subduction starts to
consume the hyperextended margin of the lower plate and to
accrete possible slivers of buoyant crustal material detached
from the subducting slab. This is a critical moment during
convergence that leads to a progressive increase of the
orogenic wedge buoyancy (increasing GPE) with the
thickening of the buoyant continental crust and incorporation
of sediments in the orogenic wedge through time (Early
Orogenesis stage, ORO-Genic IDs C3 or D3 in Fig. 1). This
mechanism reaches its maximum when the deformation front
reaches the necking line. If convergence continues and
deformation migrates beyond this line, >20 km thick crust
becomes involved in the growing orogen first on the pro-
continent side before affecting the retro-continent side
(Jammes and Huismans, 2012;Grool et al., 2019). If
convergence continues, deformation migrates across the
necking line and reaches a mature collision stage (ORO-
Genic IDs C4 or D4 Fig. 1). From these possible orogenic
tracks, it is therefore clear that a pre-convergence template
with different maturity of divergence along strike, such as the
Biscay-Pyrenees system, leads to different maturity of
convergence along strike and, in a system that continues to
converge, different timing for maturity changes with marked
Page 13 of 21
E. Masini et al.: BSGF 2024, 195, 23

boundary effects on lateral segments. For example, if a mature
collisional level is reached leading to plate convergence
deceleration (counteracting gravity forces and rupture of a
thick lithosphere), it could laterally force slab-roll back if
convergent maturity decreases laterally to a mature subduction
stage. Therefore, complex orogenic systems may derive from
variable maturity of divergence along strike (e.g., Biscay-
Pyrenean and Alpine systems) and as such, determining the
nature and width of the consumable domain is key to
constraining 3D boundary conditions to better understand
orogenic records in space and time.
5.3 Limitation of the approach
The ORO-Genic ID concept is based on the recognition of
diagnostic criteria that are listed in Tables 1 and 2. As such, it
can only be applied if the necessary data sets are available.
Another key limitation is that the concept is based on Western
European Orogens that were preceded by magma-poor
Tethyan divergent systems. In contrast, orogens that were
preceded by magma-rich margins are notably rarely reported in
the Meso-Cenozoic record, even though magma-rich margins
represent up to half of modern rifted margins and might not
have been rarer in earlier Earth history. This anomaly may
either be because magma-rich margins tend to be completely
subducted before mature continental collision, or they are not
recognized and/or have been misinterpreted. Recently, Gómez-
Romeu et al. (2023) and Ganade et al. (2023) suggest that such
margins are indeed mostly subducted and therefore not
accreted in early and collisional orogens. Based on geological/
geophysical observations and numerical experiments, Gómez-
Romeu et al. (2023) propose that the lack of deep-water syn-
rift strata or thick piles of syn-rift sediments and the absence of
distal margins domains preserved in an orogen may point to the
existence of a former magma-rich margin. However, if these
results suggest that magma-rich and magma-poor margins
behave differently during subduction (Gómez-Romeu et al.,
2023;Ganade et al. 2023), these questions are still in the first
stages of research. Applying the ORO-Genic ID approach to
Middle East orogens (e.g. Zagros) has already led us to
recognize fingerprints of magma-rich margin-derived orogens
supported by recent petrological studies (Azizi et al., 2023).
While not providing clear proof, noting the absence of
diagnostic criteria represents valuable information that can
contribute to the definition of an orogenic ID. Future research
aims to further develop this “code”by adding orogenic tracks
for magma-rich rifted and transform margins.
While the ORO-Genic concept allows us to understand the
first order lifecycle of an orogenic system resulting from the
reactivation of magma-poor rifted margins, the occurrence of
local specificities such as crustal blocks (e.g., extensional
allochthons, ribbons, microcontinents; for definitions see
Péron-Pinvidic and Manatschal (2010)), strongly segmented
margins, 3D boundary conditions, or complex kinematic
evolutions are not yet integrated and could also be key in
controlling, in particular, early orogenic records. Theses
specificities may help to explain complex sequences of
compression, extension, transient roll-back and delamination
in internal parts of orogens and may help address the question
regarding mechanisms of exhumation of ultra-high-pressure
rocks as observed in the Alps (Malusà et al., 2011;Froitzheim
et al., 2003). Note also, that the post-rift thermal relaxation
time that controls the initial thermal conditions of the orogenic
system (Salazar-Mora et al., 2018;Sacek et al., 2022) and the
thermo-mechanical, kinematics and climate forcing parame-
ters are not considered in the Wilson Cycle 2.0 but are known
to affect orogenic processes and syn orogenic basins (Jammes
and Huismans, 2012;Angrand et al., 2018;Vasey et al., 2024).
Last but not least, another new perspective unlocked by the
ORO-Genic ID concept is to switch the understanding of
orogens from a chrono-tectonic to an ORO-Genic viewpoint.
In helping us to deter- mine and date in a consistent way the
maturity of divergence (i.e. the pre-orogenic template), the
maturity of convergence and the nature/age of post-orogenic
records, the ORO-Genic ID concept opens the possibility of
studying spatial lithospheric coupling between different
orogenic branches/sub-belts across diffuse plate boundary
(see Mouthereau et al. (2021)). It also questions the role of
subduction in space and time in convergent settings (see Jolivet
et al. (2021)).
5.4 Implications for industry
The first order concept and methodology proposed in this
paper are typically designed for crustal/basin-scale applica-
tions. As such, they provide significant value for rapid
diagnostic assessments of orogenic provinces and their
associated basins. One of the key aspects of the ORO-Genic
concept is to understand their geodynamic evolution through
the identification of their tectonic track. In the Pyrenean
system, it has been clearly demonstrated that most of the play
elements of the oil and gas system are inherited from the pre-
convergence history (see Biteau et al. (2006) for a review).
The presence or absence of these elements depends on the
preservation of (hyper)extended rift domains within the
orogen, which in turn relies on the convergent maturity. In
systems that do not reach the mature collision stage, such as the
Basque-Cantabrian Basin, preservation is maximized. In more
mature collisional settings, like the Pyrenees sensu stricto,
preservation is limited to the retro-wedge of the orogen or
located at the junction between two former rift segments
(Lescoutre and Manatschal, 2020). Whatever the targeted
resources, we believe this approach enables explorers to
contextualize plays within a coherent tectonic framework,
making it applicable to mineral system in mining, petroleum
system for oil and gas and hydrogen system for geological
(white) hydrogen as already adopted by companies.
6 Conclusion
As presented in this paper, the OROGEN project provided
keys to genetically compare the different orogenic systems of
the Africa-Iberia-Europe diffuse plate boundary. Motivated by
the idea of challenging the “classical Wilson cycle”, the
OROGEN project investigated the roles of different divergent
and convergent maturities and their impact on orogenic and
post-orogenic processes. In this respect, in proposing the
Wilson cycle 2.0 and developing a new tool to map collisional
orogens in a genetic (or process-driven) way, the OROGEN
project has successfully challenged the preconceived “Orogen
Page 14 of 21
E. Masini et al.: BSGF 2024, 195, 23

singularity”assumption. It redefines what are the unpredict-
able geological specificities (regional and not genetic) from
what can be genetically predicted, by identifying for a
specific orogen its tectonic track across the Wilson cycle 2.0.
We propose, based on diagnostic criteria and the ORO-Genic
questions listed in Tables 1 and 2, to determine the
divergence and convergence maturity of an orogen and to
identify its ORO-Genic ID. Each ORO-Genic ID character-
izes the evolution and the architectural type of an orogenic
system and explains differences in the style of deformation at
crustal scale and the type of tectono-stratigraphic and
magmatic records. In a complex orogenic system presenting
variation along strike of the ORO-Genic ID (and therefore
the maturity of the divergence and the nature and width of the
consumable domain existing before convergence) is key to
constraining 3D boundary conditions and to understanding
orogenic non-cylindricity and so-called anomalies. More-
over, at a larger scale, the ORO-Genic ID is a mappable
concept that, within limitations, can be easily exported to
other orogens and will help us to compare and to classify
orogens worldwide.
Acknowledgments
This study was funded by the Orogen project, a tripartite joint
academic-industry research program between the CNRS, BRGM, and
Total R&D Frontier Exploration program. The authors salute and
thank the whole Orogen Community and especially all the PhD
students and post-doc fellows and their advising team. They also
would like to namely thank Stephane Raillard, Eric Gaucher,
Charlotte Fillon, Laure Moen-Morel, Magalie Collin, Aurélien
Virgone, Claude Goux, Marc Lescanne, Marc Martin and Veronique
Miegebielle from the Total R&D team, Thierry Baudin and Pierre
Toulhoat from the BRGM and Stephane Guillot from the CNRS. This
work has grown from and greatly benefited from discussions with
them all. More personally, Emmanuel Masini wants to warmly thanks
Josep-Anton Munoz and Julie Tugend for fruitfull discussions, Jean-
Claude Ringenbach for his constructive challenge and the M&U
Research team (Maxime Ducoux, Julia Gomez-Romeu and Rodolphe
Lescoutres) for their inputs and discussions. Finally, the authors thank
Adrian Pfiffner and Jean-Marc Lardeaux for their constructive
comments that helped to improve the manuscript as well as the Editor
Laurent Jolivet and the Associated Editor Romain Augier for
handling the manuscript.
References
Alvarez-Marron J, Rubio E, TorneM. 1997. Subduction-related
structures in the north Iberian margin, J Geophys Res: Solid Earth
102(B10): 22497–22511.
Angrand P, Mouthereau F. 2021. Evolution of the alpine orogenic
belts in the western mediterranean region as resolved by the
kinematics of the Europe-Africa diffuse plate boundary. BSGF-
Earth Sci Bull 192: 42.
Angrand P, Ford M, Watts AB. 2018. Lateral variations in foreland
flexure of a rifted continental margin: the aquitaine basin (SW
France). Tectonics 37: 430–449.
Angrand P, Mouthereau F, Masini E, Asti R. 2020. A reconstruction of
Iberia accounting for western Tethys-North Atlantic kinematics
since the late-Permian-Triassic. Solid Earth 11: 1313–1332.
Azizi H, Stern RJ, Kandemir R, Karsli O. 2023. A Jurassic volcanic
passive margin in Iran and Turkey. Terra Nova 35: 141–152.
Beauchamp W, Allmendinger RW, Barazangi M, Demnati A, El Alji
M, Dahmani M. 1999. In- version tectonics and the evolution of
the high atlas mountains, morocco, based on a geological-
geophysical transect. Tectonics 18: 163–184.
Bezada M, Humphreys E, Toomey D, HarnafiM, Davila J, Gallart J.
2013. Evidence for slab rollback in westernmost mediterranean
from improved upper mantle imaging. Earth Planet Sci Lett 368:
51–60.
Biteau J-J., Le Marrec A, Le Vot M, Masset J-M. 2006. The aquitaine
basin, Petroleum Geoscience, 12: 247–273.
Boillot G, Montadert L, Lemoine M, Biju-Duval B. 1984. Les marges
continentales actuelles et fossiles autour de la France vol. 342.
Masson Paris.
Cadenas P, Manatschal G, Fernandez-Viejo G. 2020. Unravelling the
architecture and evolution of the inverted multi-stage north Iberian-
bay of Biscay rift. Gondwana Res 88: 67–87.
Calvert A, Sandvol E, Seber D, Barazangi M, Roecker S, Mourabit T,
et al. 2000. Geodynamic evolution of the lithosphere and upper
mantle beneath the Alboran region of the western mediterranean:
constraints from travel time tomography. J Geophys Res: Solid
Earth 105: 10871–10898.
Castelltort S, Fillon C, Lasseur É, Ortiz A, Robin C, Guillocheau F,
et al. 2023. The Source-to-Sink Vade-mecum: History, Concepts
and Tools| Vade-mecum de l'approche Source-To-Sink:
Histoire, Concepts et Outils. SEPM (Society for Sedimentary
Geology).
Chenin P, Manatschal G, Picazo S, Mu
ntener O, Karner G, Johnson C,
et al. 2017. Influence of the architecture of magma-poor
hyperextended rifted margins on orogens produced by the closure
of narrow versus wide oceans. Geosphere 13: 559–576.
Chevrot S, Sylvander M, Villaseñor A, Díaz J, Stehly L,Boué P, et al.
2022. Passive imaging of collisional orogens: a review of a decade
of geophysical studies in the pyrénées imagerie passive des
orogènes collisionnels: une revue d’une décennie d’études géo-
physiques dans les pyrénées, Bulletin de la Société Géologique de
France (2022) 193 (1):1
Davies JH, von Blanckenburg F. 1995. Slab breakoff: a model of
lithosphere detachment andits test in the magmatismand deformation
of collisional Orogens. Earth Planet Sci Lett 129: 85–102.
Del Río P, Barbero L, Stuart F. 2009. Exhumation of the sierra de
Cameros (Iberian range, Spain): constraints from low-temperature
thermochronology. Geolog Soc Lond Spec Publ 324: 153–166.
Dewey JF, Bird JM. 1970. Mountain belts and the new global
tectonics. J Geophys Res 75: 2625–2647.
Ducoux M, Jolivet L, Callot, J.-P., Aubourg C, Masini E, LahfidA,
et al. 2019. The nappe des marbres unit of the basque-cantabrian
basin: the tectono-thermal evolution of a fossil hyperextended rift
basin. Tectonics 38: 3881–3915.
Ernst W. 2005. Alpine and pacific styles of phanerozoic mountain
building: subduction-zone petrogenesis of continental crust. Terra
Nova 17: 165–188.
Fernéndez-Viejo G, Gallart J, Pulgar J, Gallastegui J, Dañobeitia JJ,
Córdoba D. 1998. Crustal transition between continental and
oceanic domains along the north iberian margin from wide angle
seismic and gravity data. Geophys Res Lett 25: 4249–4252.
Ford M, Masini E, Verges J, Pik R, Ternois S, Léger J, et al. 2022.
Evolution of a low convergence collisional orogen: a review of
pyrenean orogenesis. Bull Soc Géolog France 193 (1).
Page 15 of 21
E. Masini et al.: BSGF 2024, 195, 23

Frasca G, Manatschal G, Cadenas P, Miro J, Lescoutre R. 2021. A
kinematic reconstruction of iberia using intracontinental strike-slip
corridors. Terra Nova 33: 573–581.
Frizon de Lamotte D, Zizi M, Missenard Y, Hafid M, Azzouzi ME,
Maury R, et al. 2008. The atlas system, Continental Evolution: The
Geology of Morocco: Structure, Stratigraphy, and Tectonics of the
Africa-Atlantic-Mediterranean Triple Junction, pp. 133-202.
Froitzheim N, Pleuger J, Roller S, Nagel T. 2003. Exhumation of
high-and ultrahigh-pressure metamorphic rocks by slab extraction.
Geology 31: 925–928.
Ganade, C, Riel N, Manatschal G, Tesser LR, Rubatto D, Herman J,
et al. Emergence of modern-style continetal subduction modulated
by rifted margin-subduction feedback, 05 July 2023, preprint
(Version1) available at Research square
García-Lasanta C, Casas-Sainz A, Villalaín J, Oliva-Urcia B,
Mochales T, & Speranza, F, 2017. Remagnetizations used to
unravel large-scale fold kinematics: A case study in the cameros
basin (northern spain),Tectonics, 36(4), 714–729
Giese P, Jacobshagen V. 1992. Inversion tectonics of intracontinental
ranges: High and middle atlas, morocco. Geologische Rundschau
81: 249–259.
Gimeno-Vives O, Mohn G, Bosse V, Haissen F, Zaghloul MN,
Atouabat A, et al. 2019. The mesozoic margin of the maghrebian
tethys in the rif belt (morocco): Evidence for polyphase rifting and
related magmatic activity. Tectonics 38: 2894–2918.
Gómez-Romeu J, Masini E, Tugend J, Ducoux M, Kusznir N. 2019.
Role of rift structural inheritance in orogeny highlighted by the
western pyrenees case-study. Tectonophysics 766: 131–150.
Gómez-Romeu J, Jammes S, Ducoux M, Lescoutre R, Calassou S, Masini
E. 2023. Inverted magma- rich versus magma-poor rifted margins:
Implications for early orogenic systems. Tekt o n ika 1: 49–66.
Grool AR, Huismans RS, Ford M. 2019. Salt décollement and rift
inheritance controls on crustal deformation in orogens. Terra Nova
31: 562–568.
Handy MR, Schmid SM, Bousquet R, Kissling E, Bernoulli D. 2010.
Reconciling plate-tectonic reconstructions of alpine tethys with the
geological-geophysical record of spreading and subduction in the
alps. Earth-Sci Rev 102: 121–158.
Jammes S, Huismans RS. 2012. Structural styles of mountain
building: Controls of lithospheric rheologic stratification and
extensional inheritance, J Geophys Res: Solid Earth 117 (B10).
Jammes S, Manatschal G, Lavier L, Masini E. 2009. Tectonosedimentary
evolution related to extreme crustal thinning ahead of a propagating
ocean: example of the western Pyrenees. Tectonics 28(4).
Jolivet L, Romagny A, Gorini C, Maillard A, Thinon I, CoueffeR,
et al. 2020. Fast dismantling of a mountain belt by mantle flow:
late-orogenic evolution of pyrenees and liguro-provencal rifting.
Tectonophysics 776: 228312.
Jolivet L, Baudin T, Calassou S, Chevrot S, Ford M, Issautier B, et al.
2021. Geodynamic evolution of a wide plate boundary in the
western mediterranean, near-field versus far-field interactions,
BSGF-Earth Sci Bull 192: 48.
Lacombe O, Bellahsen N. 2016. Thick-skinned tectonics and
basement-involved fold-thrust belts: insights from selected
cenozoic orogens. Geolog Mag 153: 763–810.
Lagabrielle Y, Bodinier J-L. 2008. Submarine reworking of exhumed
subcontinental mantle rocks: field evidence from the Lherz
Peridotites, French Pyrenees. Terra Nova 20: 11–21.
Lagabrielle Y, Labaume P, de Saint Blanquat M. 2010. Mantle
exhumation, crustal denudation, and gravity tectonics during
cretaceous rifting in the Pyrenean realm (SW Europe): insights
from the geological setting of the lherzolite bodies. Tectonics 29(4).
Lemoine M, Tricart P, Boillot G, 1987. Ultramafic and gabbroic ocean
floor of the ligurian tethys (alps, corsica, apennines): in search of a
genetic model. Geology 15: 622–625.
Leprêtre R, Missenard Y, Barbarand J, Gautheron C, Jouvie I, Saddiqi
O. 2018. Polyphased inversions of an intracontinental rift: case
study of the marrakech high atlas, morocco. Tectonics 37: 818–841.
Lescoutre R, Manatschal G. 2020. Role of rift-inheritance and
segmentation for orogenic evolution: example from the pyrenean-
cantabrian system rôle de l’héritage associé au rift et à sa
segmentation pour l’évolution orogénique: exemple du système
pyrénéo-cantabrique. Bull Soc Géolog France 191(1).
Lescoutre R, Tugend J, Brune S, Masini E, Manatschal G. 2019.
Thermal evolution of asymmetric hyperextended magma-poor rift
systems: results from numerical modeling and pyrenean field
observations. Geochem Geophys Geosyst 20: 4567–4587.
Macchiavelli C, Vergés J, Schettino A, Fernàndez M, Turco E,
Casciello E, et al. 2017. A new southern North Atlantic isochron
map: insights into the drift of the Iberian plate since the late
cretaceous. J Geophys Res: Solid Earth 122: 9603–9626.
Malusà MG, Faccenna C, Garzanti E, Polino R. 2011. Divergence in
subduction zones and exhumation of high pressure rocks (Eocene
western alps). Earth Planet Sci Lett 310: 21–32.
Manatschal G, Chenin P, Lescoutre R, MiroJ, Cadenas P, Saspiturry
N, et al. 2021. The role of inheritance in forming rifts and rifted
margins and building collisional orogens: a Biscay-Pyrenean
perspective. BSGF-Earth Sci Bull 192: 55.
Masini E, Manatschal G, Tugend J, Mohn G, Flament J-M. 2014. The
tectono-sedimentary evolution of a hyper-extended rift basin: the
example of the Arzacq-Mauléon rift system (western Pyrenees, SW
France). Int J Earth Sci 103: 1569–1596.
McCarthy A, Chelle-Michou C, Müntener O, Arculus R, Blundy J.
2018. Subduction initiation without magmatism: The case of the
missing alpine magmatic arc. Geology 46: 1059–1062.
McCarthy A, Tugend J, Mohn G. 2021. Formation of the alpine
orogen by amagmatic convergence and assembly of previously
rifted lithosphere. Elements 17: 29–34.
Miró J, Manatschal G, Cadenas P, Muñoz JA. 2021. Reactivation of a
hyperextended rift system: the Basque-Cantabrian Pyrenees case.
Basin Res 33: 3077–3101.
Miró J, Ferrer O, Muñoz JA, Manastchal G. 2022. Role of inheritance
during tectonic inversion of a rift system in a thick-to thin-skin
transition: analogue modelling and application to the Pyrenean-
Biscay system. EGUsphere 1–37.
Mohn G, Manatschal G, Mu
ntener O, Beltrando M, Masini E. 2010.
Unravelling the interaction between tectonic and sedimentary
processes during lithospheric thinning in the alpine tethys margins.
Int J Earth Sci 99: 75–101.
Mouthereau F, Angrand P, Jourdon A, Ternois S, Fillon C, Calassou S,
et al. 2021. Cenozoic mountain building and topographic evolution
in Western Europe: impact of billions of years of lithosphere
evolution and plate kinematics, BSGF-Earth Sci Bull 192: 56.
Omodeo Salè S, Guimerà J, Mas R, Arribas J. 2014. Tectono-
stratigraphic evolution of an inverted extensional basin: the
cameros basin (north of Spain). Int J Earth Sci 103: 1597–1620.
Pedrera A, Ruiz-Constan A, García-Senz J, Azor A, Marín-Lechado
C, Ayala C, et al. 2020. Evolution of the south-iberian paleomargin:
From hyperextension to continental subduction. J Struct Geol 138:
104122.
Page 16 of 21
E. Masini et al.: BSGF 2024, 195, 23

Péron-Pinvidic G, Manatschal G. 2010. From microcontinents to
extensional allochthons: witnesses of how continents rift and break
apart? Petrol Geosci 16: 189–197.
Picazo S, Müntener O, Manatschal G, Bauville A, Karner G, Johnson
C. 2016. Mapping the nature of mantle domains in western and
central Europe based on clinopyroxene and spinel chemistry:
Evidence for mantle modification during an extensional cycle.
Lithos 266: 233–263.
Platt NH. 1990. Basin evolution and fault reactivation in the western
cameros basin, northern Spain. J Geolog Soc 147: 165–175.
Pognante U, Perotto A, Salino C, Toscani L. 1986. The ophiolitic
peridotites of the western alps: Record of the evolution of a
small oceanic-type basin in the mesozoic Tethys. TMPM
Tschermaks Mineralogische und Petrographische Mitteilungen
35: 47–65.
Puga E, Fanning M, de Federico AD, Nieto JM, Beccaluva L,
Bianchini G, et al. 2011. Petrology, geochemistry and U-Pb
geochronology of the betic ophiolites: inferences for pangaea
break-up and birth of the westernmost Tethys ocean. Lithos 124:
255–272.
Rat J, Mouthereau F, Brichau S, Cremades A, Bernet M, Balvay M,
et al. 2019. Tectonothermal evolution of the Cameros basin:
implications for tectonics of North Iberia. Tectonics 38: 440–469.
Rosenbaum G, Lister GS. 2005. The western alps from the Jurassic to
oligocene: spatio-temporal con- straints and evolutionary recon-
structions. Earth-Sci Rev 69 (3-4), 281–306.
Ruiz Fernàndez, M., 2007. Caracterització estructural i sismotectòn-
ica de la litosfera en el domini Pirenaico-Cantàbric a partir de
mètodes de sísmica activa i passiva., Universitat de Barcelona
Sacek V, Ussami N, Pesce A, Mora CS, dos Santos EB, Baiadori F,
Assunçao J, Silva JPM, da Silva RM, Bicudo TC. 2022.
Computational geodynamics of the South American plate:
contributions and perspectives. Br J Geophys 40: 125–136.
Salas R, Guimerà J, Mas R, Martin-Closas C, Melendez A, Alonso A.
2001. Evolution of the mesozoic central iberian rift system and its
cainozoic inversion (Iberian chain). Mémoires du Muséum national
d’histoire naturelle (1993) 186: 145–186.
Salazar-Mora CA, Huismans RS, Fossen H, Egydio-Silva M. 2018.
The Wilson cycle and effects of tectonic structural inheritance on
rifted passive margin formation. Tectonics 37: 3085–3101.
Saspiturry N, Razin P, Baudin T, Serrano O, Issautier B, Lasseur E,
et al. 2019. Symmetry vs. asymmetry of a hyper-thinned rift:
Example of the mauléon basin (Western Pyrenees, France). Mar
Petrol Geol 104: 86–105.
Séranne M, Couëffé R, Husson E, Baral C, Villard J. 2021. The
transition from Pyrenean shortening to gulf of lion rifting in
Languedoc (south France) a tectonic-sedimentation analysis.
BSGF-Earth Sci Bull 192: 27.
Teixell A, Arboleya M-L., Julivert M, Charroud M. 2003. Tectonic
shortening and topography in the central high atlas (morocco).
Tectonics 22(5).
Teixell A, Labaume P, Lagabrielle Y. 2016. The crustal evolution of
the west-central pyrenees revisited: Inferences from a new
kinematic scenario. Comptes Rendus Geosci 348: 257–267.
Tugend J, Manatschal G, Kusznir N, Masini E, Mohn G, Thinon I.
2014. Formation and deformation of hyperextended rift systems:
Insights from rift domain mapping in the bay of biscay-pyrenees.
Tectonics 33: 1239–1276.
Uyeda S. 1981. Subduction zones and back arc basins—a review,
Geologische Rundschau 70: 552–569.
Vasey DA, Naliboff JB, Cowgill E, Brune S, Glerum A, Zwaan F.
2024. Impact of rift history on the structural style of intra-
continental rift-inversion orogens, Geology. 52(6), 429–434.
Villaseñor A, Chevrot S, HarnafiM, Gallart J, Pazos A, Serrano I,
et al. 2015. Subduction and volcanism in the iberia-north africa
collision zone from tomographic images of the upper mantle.
Tectonophysics 663: 238–249.
Vlaar N, Cloetingh S. 1984. Orogeny and ophiolites: Plate tectonics
revisited with reference to the alps.Geologie en Mijnbouw 63: 159–164.
Willett S, Beaumont C, Fullsack P. 1993. Mechanical model for the
tectonics of doubly vergent com- pressional orogens. Geology 21:
371–374.
Wilson JT. 1966. Did the atlantic close and then re-open? Nature 211:
676–681.
Cite this article as: Masini E, Jammes S, Calassou S, Vidal O, Thinon I, Manatschal G, Chevrot S, Ford M, Mouthereau F, Lacombe O. 2024.
Revisiting orogens during the OROGEN project: tectonic maturity, a key element to understand orogenic variability. BSGF - Earth Sciences
Bulletin 195: 23.
Page 17 of 21
E. Masini et al.: BSGF 2024, 195, 23

Fig. A1. On the right: Wilson cycle updated for tectonic track A. In the case of the end of convergence, the post-convergent scenario is
illustrated on the left side of the figure.
Appendix
Page 18 of 21
E. Masini et al.: BSGF 2024, 195, 23

Fig. A2. On the right: Wilson cycle updated for tectonic track B. In the case of the end of convergence, different post-convergent scenarios are
possible depending of the maturity stage of the convergence. Those scenarios are illustrated on the left side of the figure.
Page 19 of 21
E. Masini et al.: BSGF 2024, 195, 23

Fig. A3. On the right: Wilson cycle updated for tectonic track C. In the case of the end of convergence, different post-convergent scenarios are
possible depending of the maturity stage of the convergence. Those scenarios are illustrated on the left side of the figure.
Page 20 of 21
E. Masini et al.: BSGF 2024, 195, 23

Fig. A4. On the right: Wilson cycle updated for tectonic track D. In the case of the end of convergence, different post-convergent scenarios are
possible depending of the maturity stage of the convergence. Those scenarios are illustrated on the left side of the figure.
Page 21 of 21
E. Masini et al.: BSGF 2024, 195, 23