Camille Raulin

Bio: Camille Raulin is an academic researcher from Cergy-Pontoise University. The author has contributed to research in topics: Permian & Sedimentology. The author has an hindex of 3, co-authored 4 publications receiving 339 citations.

The southernmost margin of the Tethys realm during the Mesozoic and Cenozoic: Initial geometry and timing of the inversion processes

Abstract: [1] Along the northern border of Africa, Pangea breakup has been diachronic. During the Jurassic, the Alpine Tethys propagated northeastward from the Atlantic to the Alps. During the Permian, the Neo-Tethys propagated westward from Oman to northwestern Arabia. Then a secondary and late branch of Neo-Tethys gave birth to the East Mediterranean basin. Finally the two oceans connected at end of Jurassic times, achieving the development of Africa northern plate boundary. By the Late Cretaceous, convergence between Africa and Eurasia led to the progressive closure of the Tethys realm. The continental collision is not completely achieved, and the different segments of the confrontation zone (Maghreb, central and East Mediterranean, Zagros, and Oman) expose different stages of the process. However, we emphasize the existence of synchronous geodynamic events from one end of the system to the other, although they do not have the same meaning. Two of them are particularly important. The Campanian-Santonian (C-S) event corresponds to (1) obduction and exhumation of high-pressure–low-temperature metamorphic rocks around the Arabian promontory, (2) inversion along the margins of the East Mediterranean basins, and (3) lithosphere buckling in the Atlas system (Maghreb) and adjacent Sahara platform. The middle-late Eocene (MLE) event corresponds to (1) the onset of collision at the northern corner of Arabia, (2) the onset of slab retreat in the Mediterranean, and (3) inversion along the margin of the East Mediterranean as well as in the Atlas. The C-S event coincides with a change in plate kinematics resulting in an abrupt increase of convergence velocity. The MLE event coincides with a period of strong coupling between the Africa and Eurasia plates and an abrupt decrease of convergence velocity. In the middle of the system, the central Mediterranean seems to escape to the effects of convergence and is the site of quite permanent extensional movements since the Triassic.

Evidence for Late Devonian vertical movements and extensional deformation in northern Africa and Arabia: Integration in the geodynamics of the Devonian world

Abstract: [1] The Upper Paleozoic geodynamic evolution is discussed at the scale of a wide part of Gondwana from North Africa to Arabia. With the aim of giving an integrated tectonic scenario for the study domain, we revisit six key areas, namely, the Anti-Atlas Belt (Morocco), the Bechar Basin (west Algeria), the Hassi R'Mel High (central Algeria), the Talemezane Arch (south Tunisia), the Western Desert (Egypt), and, finally, the High Zagros Belt (Iran). Below the so-called “Hercynian unconformity,” which is in reality a highly composite discontinuity, surface and subsurface data display a well-known arch-and-basin geometry, with basement highs and intervening Paleozoic basins. We show that this major feature results mainly from a Late Devonian event and can no longer be interpreted as a far effect of the Variscan Orogeny. This event is characterized by a more or less diffuse extensional deformation and accompanied either by subsidence, in the western part of the system, or by an important uplift of probable thermal origin followed by erosion and peneplanation. By the end of the Devonian, the whole region suffered a general subsidence governed by the progressive cooling of the lithosphere. Such a primary configuration is preserved in Arabia with typical sag geometry of the Carboniferous and Permian deposits but strongly disturbed elsewhere by the conjugated effects of the Variscan Orogeny during the Carboniferous and/or by subsequent uplifts linked to the central Atlantic and Neo-Tethys rifting episodes. In conclusion, we try to integrate this new understanding in the geodynamics of the Late Devonian, which at world scale is characterized by the onset of the Variscan Orogeny on the one hand and by magmatism, rifting, and basement uplift on the other hand.

Sedimentology and Stratigraphy of the Early to Middle Triassic Clastic Formations of the Ghadames Basin (Tunisia-Libya)

Abstract: During the opening of the Neotethys Ocean north of the Ghadames basin, an extensional phase created subsidence. It resulted in the deposition of the first syn-rift strata aged Middle to Upper Permian (El Watiah formation) and Lower to Middle Triassic (Bir el Jaja, Ouled Chebbi and Ras Hamia / Kirchaou formations). The study provides details of the stratigraphic and sequential architecture of Triassic siliciclastic series and the upper clastic part of the El Watiah formation. 221 wells and 18 sedimentological outcrop sections (rocks exposed in southern Tunisia) have been correlated across the entire Ghadames basin. An organization in 11 sequences has been highlighted. 28 isochores and paleogeographic maps have been drawn. In terms of tectonostratigraphy, a major thickening of sequences has been confirmed toward the North of the basin, resulting from a very strong and differential subsidence. In addition, low and subtle differential subsidence has been demonstrated in the southern part of the basin.

Origin and consequences of western Mediterranean subduction, rollback, and slab segmentation

Abstract: The western Mediterranean recorded subduction rollback, slab segmentation and separation. Here we address the questions of what caused Oligocene rollback initiation, and how its subsequent evolution split up an originally coherent fore arc into circum-southwest Mediterranean segments. We kinematically reconstruct western Mediterranean geology from subduction initiation to present, using Atlantic plate reconstructions as boundary condition. We test possible reconstructions against remnants of subducted lithosphere imaged by seismic tomography. Transform motion between Africa and Iberia (including the Baleares) between ~120 and 85 Ma was followed by up to 150 km convergence until 30 Ma. Subduction likely initiated along the transform fault that accommodated pre-85 Ma translation. By the ~30 Ma inception of rollback, up to 150 km of convergence had formed a small slab below the Baleares. Iberia was disconnected from Sardinia/Calabria through the North Balearic Transform Zone (NBTZ). Subduction below Sardinia/Calabria was slightly faster than below the Baleares, the difference being accommodated in the Pyrenees. A moving triple junction at the trench-NBTZ intersection formed a subduction transform edge propagator fault between the Baleares and Calabria slab segments. Calabria rolled back eastward, whereas the Baleares slab underwent radial (SW-S-SE) rollback. After Kabylides-Africa collision, the western slab segment retreated toward Gibraltar, here reconstructed as the maximum rollback end-member model, and a Kabylides slab detached from Africa. Opening of a slab window below the NBTZ allowed asthenospheric rise to the base of the fore arc creating high-temperature metamorphism. Western Mediterranean rollback commenced only after sufficient slab-pull was created from 100 to 150 km of slow, forced subduction before ~30 Ma.

Map view restoration of Aegean–West Anatolian accretion and extension since the Eocene

Abstract: [1] The Aegean region (Greece, western Turkey) is one of the best studied continental extensional provinces. Here, we provide the first detailed kinematic restoration of the Aegean region since 35 Ma. The region consists of stacked upper crustal slices (nappes) that reflect a complex paleogeography. These were decoupled from the subducting African-Adriatic lithospheric slab. Especially since ∼25 Ma, extensional detachments cut the nappe stack and exhumed its metamorphosed portions in metamorphic core complexes. We reconstruct up to 400 km of trench-perpendicular (NE-SW) extension in two stages. From 25 to 15 Ma, the Aegean forearc rotated clockwise relative to the Moesian platform around Euler poles in northern Greece, accommodated by extensional detachments in the north and an inferred transfer fault SE of the Menderes massif. The majority of extension occurred after 15 Ma (up to 290 km) by opposite rotations of the western and eastern parts of the region. Simultaneously, the Aegean region underwent up to 650 km of post-25 Ma trench-parallel extension leading to dramatic crustal thinning on Crete. We restore a detachment configuration with the Mid-Cycladic Lineament representing a detachment that accommodated trench-parallel extension in the central Aegean region. Finally, we demonstrate that the Sakarya zone and Cretaceous ophiolites of Turkey cannot be traced far into the Aegean region and are likely bounded by a pre-35 Ma N-S fault zone. This fault became reactivated since 25 Ma as an extensional detachment located west of Lesbos Island. The paleogeographic units south of the Izmir-Ankara-Sava suture, however, can be correlated from Greece to Turkey.