Éditeur(s) : HAL CCSD
Résumé : International audience
Compilation of new and published apatite fission track data along atransect of the west-central Pyrenees shows that exhumation across thePartial Annealing Zone (~120–60°C) started during the mid Eocene inthe North-Pyrenean Zone and migrated southward to reach the southernedge of the Axial Zone during the early Miocene. An early Miocene stageof exhumation is also detected in the northern part of the Axial Zone,indicating a late pop-up thrust reactivation of the Axial Zone.
La compilación de datos nuevos y pre-existentes de huellas de fisión enapatito a lo largo de un perfil de los Pirineos centro-occidentales muestra quela exhumación a través de la Partial Annealing Zone (~120–60°C) comenzó enel Eoceno medio en la Zona Norpirenaica, y fue migrando hacia el sur hastaalcanzar el borde meridional de la Zona Axial en el Mioceno inferior. Al nortede la Zona Axial se registra así mismo una marcada exhumación durante el Miocenoinferior, indicando una reactivación cabalgante en pop-up de la Zona Axial.
Geogaceta

Droits : info:eu-repo/semantics/OpenAccess
insu-01425009
https://hal-insu.archives-ouvertes.fr/insu-01425009
https://hal-insu.archives-ouvertes.fr/insu-01425009/document
https://hal-insu.archives-ouvertes.fr/insu-01425009/file/PL03665.pdf

Éditeur(s) : HAL CCSD American Geophysical Union (AGU)
Résumé : International audience
Apatite fission track analysis (AFTA) data are used to bring new light on the long-term and recent history of the Baikal rift region (Siberia). We describe the evolution of the topography along a NW-SE profile from the Siberian platform to the Barguzin range across the Baikal-southern Patom range and the northern termination of Lake Baikal. Our results show that the Baikal-Patom range started to form in the Early Carboniferous and was reactivated in Middle Jurassic-Lower Cretaceous times during the orogenic collapse of the Mongol-Okhotsk belt. Samples located in the Siberian platform recorded a continuous sedimentation up to the early Carboniferous but remain unaffected by later tectonic episodes. The Barguzin basin probably started to form as early as Late Cretaceous, suggesting a continuum of deformation between the postorogenic collapse and the opening of the Baikal Rift System (BRS). The initial driving mechanism for the opening of the BRS is thus independent from the India-Asia collision. AFTA show a late Miocene-early Pliocene increase in tectonic extension in the BRS that confirms previous thoughts and might reflect the first significant effect of the stress field generated by the India-Asia collision.
ISSN: 0278-7407

hal-00420895
https://hal.archives-ouvertes.fr/hal-00420895
DOI : 10.1029/2008TC002404

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The dating of the uplift onset of the Mongolian mountain ranges, the northernmost relief associated with the India-Eurasia convergence, is a fundamental issue to better understand the mechanisms of propagation of the Cenozoic transpressive deformation in Central Asia. Using apatite fission tracks we determined the timing and strain rates of the tectonics affecting the Gurvan Bogd system, in the Gobi-Altay, since the Middle Mesozoic to the Late Cenozoic. The region was firstly affected by a Lower-Middle Jurassic tectonic phase, characterized by a vertical crustal movement larger than 2 km. Then followed a protracted period without major crustal vertical movements until the last uplift phase. The peneplanation of the Jurassic relief produced an erosional surface that has undergone negligible denudation or sedimentation for more than 100 Ma. This same surface corresponds to the present summit plateaux of the massifs, standing about 2000 m above the surrounding region, which corresponds to the vertical movement produced by the ongoing uplift. Modelling of fission track data from the massifs of Ih Bogd and Baga Bogd shows that this uplift phase probably started at 5 ± 3 Ma. The Gobi-Altay mountain range appears therefore as one of the youngest mountain ranges in Central Asia, which is consistent with the idea of a northward propagation of the transpressional deformation from the Himalayan front to the Siberian craton. The Cenozoic uplift rate of the massifs is estimated to be between 0.25 and 1 mm/yr, which is slightly higher than the upper Pleistocene vertical slip rates of the bordering faults. This suggests that thrust faults observed within the massifs would increase the uplift rate inside the massifs compared to the uplift rate determined at their boundaries.
ISSN: 0012-821X

insu-00191116
https://hal-insu.archives-ouvertes.fr/insu-00191116
DOI : 10.1016/j.epsl.2007.04.047

Éditeur(s) : HAL CCSD American Geophysical Union (AGU)
Résumé : International audience
The Vertiskos Unit of northern Greece is an elongated basement belt with a complex poly-metamorphic history. It extends from Greece (Chalkidiki peninsula), to the south, up to Serbia, in the north, and arguably represents the westernmost part of the Rhodope Metamorphic Province (northern Greece to southern Bulgaria). The Vertiskos Unit experienced a medium pressure lower amphibolite-facies metamorphic overprint during the Alpine Orogeny. The available medium-temperature geochronology implies that it remained at temperature of approximately 300°C (or slightly higher) during Lower Cretaceous. In order to constrain its post-Lower Cretaceous thermal history, until near-surface exposure, we applied apatite fission track analysis. The central ages obtained range from 68.5 ± 3.8 to 46.6 ± 3.6 Ma (uppermost Cretaceous to Middle Eocene) and mean track lengths between 13 and 13.5 μm. We applied two inverse thermal modeling approaches using either each sample independently (high degree of freedomin the thermal history, better data fit) or all samples together interpreting them as a vertical profile (simpler thermal history, worse data fit). Irrespective of the modeling approach, we conclude that the bulk thermal history of the Vertiskos Unit crosses the high-temperature limit of the apatite partial annealing zone by the uppermost Cretaceous and reaches near-surface conditions as early as lower/middle Eocene. These results contrast with the thermal history of the other domains of the Rhodope Metamorphic Province further east (namely the Southern Rhodope Core Complex and the Northern Rhodope Complex) and establish the Vertiskos basement complex as the oldest exhumed coherent basement fragment of the Rhodope Metamorphic Province and Greece.
ISSN: 0278-7407

insu-01053579
https://hal-insu.archives-ouvertes.fr/insu-01053579
https://hal-insu.archives-ouvertes.fr/insu-01053579/document
https://hal-insu.archives-ouvertes.fr/insu-01053579/file/Kydonakis-brun-tectonics-2014.pdf
DOI : 10.1002/2014TC003572

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The high proportion of crystallized apatite forming the bones and teeth should theoretically allow the use of fission track analysis to date vertebrate fossils when burying of the fossiliferous series did not subject them to temperatures exceeding 60 degrees C. However several major obstacles arise such as the complexity of fossils' internal structures, diagenetic modifications and substitutions of the hydroxyapatite by other minerals, and massive U uptake or loss during diagenesis. In this work, those various problems are addressed combining optical microscope observation of the fossils, a systematic fission track analysis of the best samples, alpha and gamma spectrometry and Secondary Ion Mass Spectrometry. Even if the problems caused by internal structures and mineral substitutions can be solved, U movements in and out of the fossils are generally too complex to allow fission track analysis dating of the fossils.
ISSN: 0009-2541

hal-00411880
https://hal.archives-ouvertes.fr/hal-00411880
DOI : 10.1016/j.chemgeo.2007.10.009

Éditeur(s) : HAL CCSD
Résumé : In this work on a complete transect of the west‐central Pyrenees, we combine low temperature thermochronology (apatite fission tracks, AFT) with a detailed structural analysis to describe vertical movements related to the thrusting system evolution, and to determine the influence of the latter on the sedimentation/burial/exhumation cycle of thesynorogenic deposits of the southern foreland basin (Jaca and Ainsa basins). AFT analysis from a transect of the south‐Pyrenean basin show the southward decrease of the fission track reset level from the southern edge of the Axial Zone to the South‐Pyreneanfrontal thrust, implying the southwards decrease of the burial amount from more than 5kmin the north to less than 3km in the south assuming an average geothermal gradient of 25°C.km‐1. The structural setting of the Jaca basin attests that the burial of the synorogenicsediments was mainly due to the sedimentary accumulation. AFT data from the northernpart of the basin display a late Oligocene‐early (middle) Miocene cooling event. Newinterpretation of industrial seismic reflection profiles across the Jaca basin suggests that the Oturia thrust is rooted in the Bielsa basement thrust, responsible for the early (‐middle) Miocene out‐of‐sequence tectonic reactivation of the southern flank of the Axial Zone (Jolivet et al., 2007). These results reveal a lower Miocene (Burdigalian ‐?Langhian) out‐of sequence episode of tectonic activity of the interior of the south‐Pyrenean foreland basin. AFT data from the Axial Zone and the North‐Pyrenean Zone confirm the general southwardmigration of the thrusting system, and also bring evidence of the late Oligocene‐lowe rMiocene out‐of‐sequence tectonic reactivation of the northern flank of the Axial Zone. All these results attest of a late Oligocene‐lower Miocene (Burdigalian‐?Langhian) "pop‐up" reactivation of the inner part of the west‐central Pyrenees, younger than the sealing of thesouth‐Pyrenean front (Aquitanian‐?Burdigalian) which is classically considered to mark the end of the Pyrenean compression. These results lead us to propose a new crustal scale evolution model of the west‐central Pyrenees in 3 stages: (i) From the Late Cretaceous to themiddle Eocene, the orogenic prism is characterised by the absence of relief, related to theinversion of Cretaceous extensional structures leading to the accretion of thin crustal units; (ii) The late Eocene‐Oligocene stage corresponds to the continental collision, marked by the creation of important relief associated with the accretion of thick crustal units; (iii) During the early Miocene, the inner part of the Pyrenean wedge is tectonically reactivated.
Ce travail de thèse concerne une transversale complète des Pyrénées centro-occidentales, où on a combiné la thermochronologie basse température (traces de fission sur apatites, TFA) avec une analyse structurale détaillée pour décrire les mouvements verticaux associés à l'évolution du système chevauchant, et pour déterminer l'influence de ce dernier sur le cycle sédimentation/enfouissement/exhumation des dépôts synorogéniques du bassin d'avant‐chaine sud (bassins de Jaca et Ainsa). L'analyse TFA complète les données déjà publiées dans la Zone Axiale et la Zone Nord‐Pyrénéenne, e tconstitue la première étude de ce genre dans un bassin d'avant‐chaîne pyrénéen. Les données TFA sur la transversale du bassin sud‐pyrénéen montrent une diminution vers le sud du degré d'effacement des traces de fission, traduisant la diminution vers le sud de la quantité d'enfouissement, supérieure à 5 km au nord et inférieure à 3 km au sud dans l'hypothèse un géotherme de 25°.km‐1. Le contexte géologique montre que l'enfouissement est principalement lié à l'accumulation des dépôts synorogéniques. Les données TFA de lapartie nord du bassin montrent un refroidissement d'âge Oligocène supérieur‐Miocèneinferieur (moyen). Par ailleurs, une nouvelle interprétation de profils de sismiques réflexiondans le bassin de Jaca montre que le chevauchement d'Oturia s'enracine dans lechevauchement de socle de Bielsa, responsable de l'exhumation tectonique hors‐séquencedu bord sud de la Zone Axiale au Miocène inférieur (‐moyen) (Jolivet et al., 2007). Cesrésultats attestent donc de l'exhumation tectonique hors‐séquence au Miocène inférieur (Burdigalien‐ ?Langhien) de la partie nord du bassin d'avant‐chaine sud‐pyrénéen. Des données TFA obtenues dans la Zone Axiale et la Zone Nord‐Pyrénéenne confirment lamigration générale vers le sud du système chevauchant, et mettent également en évidencela réactivation tectonique hors‐séquence du bord nord de la Zone Axiale à l'Oligocèneterminal‐Miocène inférieur. L'ensemble de ces résultats atteste donc de la réactivation en " pop‐up " de la parties interne des Pyrénées centre‐ouest à l'Oligocène supérieur‐Miocèneinférieur (Burdigalien‐ ?Langhien), postérieurement au scellement du front sud‐pyrénéen (Aquitanien‐ ?Burdigalien) classiquement considéré comme marquant la fin de lacompression pyrénéenne. Ces données nous ont permis de proposer un nouveau modèle d'évolution crustale des Pyrénées centro‐occidentales en 3 grandes étapes : (i) du Crétacé supérieur à l'Eocène moyen, le prisme est caractérisé par une absence de relief, en lien avec l'inversion de structures extensives crétacées conduisant à l'accrétion de petites écailles crustales ; (ii) la période Eocène supérieur‐Oligocène correspond à la collision continentale proprement dite, et est marquée par la création d'importants reliefs associés à l'accrétion d'épaisses unités crustales ; (iii) au Miocène inférieur, la partie interne du prisme pyrénéen est réactivée.
https://tel.archives-ouvertes.fr/tel-00772154

Droits : info:eu-repo/semantics/OpenAccess
tel-00772154
https://tel.archives-ouvertes.fr/tel-00772154
https://tel.archives-ouvertes.fr/tel-00772154/document
https://tel.archives-ouvertes.fr/tel-00772154/file/thesemeresse.pdf

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : The Great Glen Fault (GGF) is a major lithospheric strike-slip fault system that cuts across the Caledonian orogenic belt of Scotland. It separates the Northern Highlands terrane from the Grampian terrane. Movement history along the fault extends at least into the Early Palaeozoic. The low-temperature history of the Scottish Highlands covers a significant period from the Late Palaeozoic to the Present, but the magnitude of vertical movements that affected the GGF area during that time is still a matter of debate. Fission track analysis on detailed vertical profiles in the Ballachulish and Strontian complexes, as well as on a profile oriented northeastwards across the GGF, reveals distributed differential vertical movements along the fault during the Late Palaeozoic. The Mesozoic denudation is estimated at a maximum of 2 km before a more recent widespread exhumation event that started at around 40–25 Ma, leading to 1.6 to 2 km of erosion. La Great Glen Fault (GGF) est un système décrochant lithosphérique majeur qui traverse la chaîne calédonienne d'Écosse. Il sépare les domaines des Northern Highlands et de Grampian. L'histoire tectonique de ce système remonte au moins au Paléozoïque inférieur. L'histoire de la dénudation des Highlands d'Écosse s'étend du Paléozoïque supérieur jusqu'au Présent, mais l'ampleur des mouvements verticaux ayant affecté la zone autour du système de la GGF pendant cette période est toujours sujette à débat. Les analyses traces de fission réalisées sur des profils verticaux dans les complexes granitiques du Ballachulish et de Strontian, ainsi que sur un profil plus au nord-est à travers la GGF, mettent en évidence des mouvements différentiels distribués de part et d'autre de la faille au Paléozoïque supérieur. La dénudation mésozoïque est estimée au maximum à 2 km, avant un dernier épisode de surrection généralisée à partir de 40–25 Ma, qui provoque environ 1,6 à 2 km d'érosion.
ISSN: 1631-0713

hal-00406583
https://hal.archives-ouvertes.fr/hal-00406583
DOI : 10.1016/j.crte.2006.12.005

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The Dien Bien Phu (DBP) Fault strikes nearly perpendicular to the general tectonic framework, separating northwest Vietnam into two compartments. The DBP and Muong Lay granites are exposed respectively east and west of the fault. The U/Pb age of 277 ± 2 Ma obtained for the Muong Lay granite is similar to the age of the Chieng Khuong complex exposed within the Song Ma structure east of the DBP Fault. These two magmatic intrusions are considered as belonging to a same tectonic structure related to the subduction of the Song Ma Ocean under the Indochina Block during the Indosinian orogeny. The DBP Fault with a total post Permian dextral offset of 30-40 km shifts the Song Ma Suture. It could then be connected to the Ailao Shan-Shuanggou suture to the north. The undeformed DBP granite gave a U/Pb age of 230 ± 1 Ma sealing the Indosinian deformation on the fault. The Ladinian-Carnian activity of the fault is confirmed by the 40Ar/39Ar (biotite) age of 228 ± 4 Ma obtained from the paragneiss forming the fault zone. A geodynamic model is proposed to describe the various tectonic phases recorded by on the DBP Fault. It associates field data, stratigraphic observations, and geochronology analyses (U/Pb, Ar/Ar, fission tracks). Following the Late Triassic exhumation of the granite and the end of the Indosinian orogeny marked by the Norian unconformity, the granite was buried under Jurassic and Lower Cretaceous sediments. A strong cooling event during the early Late Cretaceous (100 Ma) is associated with the reactivation of the DBP Fault and the accommodation of a southward thrusting of the Song Da terrane onto the Truong Son Belt. This newly recognised tectonic phase could be associated to the subduction of the Paleo-Pacific plate under the Indochina Block. No data are available yet to constrain the Tertiary evolution of the DBP system. However, the Tertiary deformation is likely similar to the Cretaceous one.
ISSN: 1342-937X

insu-01015379
https://hal-insu.archives-ouvertes.fr/insu-01015379
DOI : 10.1016/j.gr.2013.07.018

Éditeur(s) : HAL CCSD American Geophysical Union (AGU)
Résumé : The role of the Karakorum fault zone (KFZ) is debated. South of 33°N, ongoing dextral-oblique slip along the SW edge of the Gar basin exhumes metamorphic and magmatic rocks of the Ayilari range. Minerals have recorded a continuum of deformation from temperatures >600–400°C down to <250_C. The 40Ar/39Ar ages, the oldest being 21.2 ± 1.0 Ma, yield minimum estimates for the initiation of the KFZ. These are in agreement with the U-Th/Pb ages constraining the onset of deformation at ca 25–22 Ma. Thermochronologic results show slow cooling for the period ca 21– 14 Ma, followed by rapid cooling between 14 and 4 Ma. These data demonstrate that right-lateral motion was in progress in the early Miocene and that shear continued at least until 4 Ma, pointing to >20 Ma of deformation along the fault. Greenschist facies deformation superimposed upon the medium- to high-grade deformation marks a kinematic change from pure dextral to dextral-normal motion associated with the onset of rapid cooling. At the regional scale, the coexistence of transtension in the Gar basin with transpression documented along the Pangong range farther north suggests another example of the ‘‘zipper tectonics'' model developed along the Red River fault. The kinematic shift induced the rise of the Ayilari range starting at 16–12 Ma and the incision of major river courses. The Indus River might have become captive of the relief at this time. The river's 120 km of apparent offset implies dextral motion at a long-term rate of ca 8.5 ± 1.5 mm/yr.
ISSN: 0278-7407

hal-00197561
https://hal.archives-ouvertes.fr/hal-00197561
https://hal.archives-ouvertes.fr/hal-00197561/document
https://hal.archives-ouvertes.fr/hal-00197561/file/Valli_Karakorum_thermochron_Tectonics_07_pre_print.pdf
DOI : 10.1029/2005TC001913

Éditeur(s) : HAL CCSD American Geophysical Union (AGU)
Résumé : International audience
The present-day topography of the Tian Shan range is considered to result from crustal shortening related to the ongoing India-Asia collision that started in the early Tertiary. In this study we report evidence for several episodes of localized tectonic activity which occurred prior to that major orogenic event. Apatite fission track analysis and (U-Th)/He dating on apatite and zircon indicate that inherited Paleozoic structures were reactivated in the late Paleozoic-early Mesozoic during a Cimmerian orogenic episode and also in the Late Cretaceous-Paleogene (around 65-60 Ma). These reactivations could have resulted from the accretion of the Kohistan-Dras arc or lithospheric extension in the Siberia-Mongolia zone. Activity resumed in the late Mesozoic prior to the major Tertiary orogenic phase. Finally, the ongoing deformation, which again reactivates inherited tectonic structures, tends to propagate inside the endoreic basins that were preserved in the range, leading to their progressive closure. This study demonstrates the importance of inherited structures in localizing the first increments of the deformation before it propagates into yet undeformed areas.
ISSN: 0278-7407

Droits : info:eu-repo/semantics/OpenAccess
hal-00551323
https://hal.archives-ouvertes.fr/hal-00551323
https://hal.archives-ouvertes.fr/hal-00551323/document
https://hal.archives-ouvertes.fr/hal-00551323/file/2010TC002712.pdf
DOI : 10.1029/2010TC002712

Éditeur(s) : HAL CCSD
Résumé : International audience
The history of the peneplain in East Sayan was studied using apatite fission-track analysis (AFTA). This method is suitable for determining the formation time of the erosional surface and estimating its denudation rate. The largest known relic of the peneplanation surface in this area is the Oka Plateau, separated from the Kropotkin Ridge by the Oka-Jombolok fault. The AFTA shows that the peneplain on the Oka Plateau formed in the Late Jurassic-Early Cretaceous. This peneplain is much younger than the erosional surfaces that persist today in the Tien Shan, Gobi Altai, and Mongolian Altai (Early Jurassic). However, it is older than the peneplain on the Chulyshman Plateau, Altai (Late Cretaceous), suggesting asynchronous formation of the ancient peneplain in Central Asia. The similar exhumation histories of samples from the Oka Plateau and Kropotkin Ridge indicate that these morphotectonic structures developed from Jurassic to late Miocene as a single block, which underwent continuous slow denudation at an average rate of 0.0175 mm/yr. Active tectonic processes in the Late Miocene caused the destruction of the peneplanation surface and its partial uplifting to different altitudes. The rate of Pliocene-Quaternary vertical movements along the Oka-Jombolok fault is roughly estimated at 0.046-0.080 mm/yr, which is several times higher than the denudation rate in this area. During the Pliocene-Quaternary, the Oka Plateau has not undergone any significant morphologic changes owing to its intermediate position between the summit plain and datum surface of East Sayan and to its partial shielding by basaltic lavas.
Russian Geology and Geophysics

insu-00839215
https://hal-insu.archives-ouvertes.fr/insu-00839215
DOI : 10.1016/j.rgg.2013.06.004

Éditeur(s) : Paris : Gide et J. Baudry, éditeurs
Siècle(s) traité(s) : 19
Provenance : Archives départementales de Guadeloupe
Permalien : http://www.manioc.org/patrimon/ADG18262
ADG18262

Éditeur(s) : HAL CCSD American Geophysical Union (AGU)
Résumé : International audience
This paper presents a new balanced structural cross-section of the Jaca thrust-sheet-top basin of the southern Pyrenees combined with paleo-thermometry and apatite fission track (AFT) thermochronology data. The cross-section, based on field data and interpretation of industrial seismic reflection profiles, allows refinement of previous interpretations of the south-directed thrust system, involving the identification of new thrust faults, and of the kinematic relationships between basement and cover thrusts from the middle Eocene to the early Miocene. AFT analysis shows a southward decrease in the level of fission track resetting, from totally reset Paleozoic rocks and lower Eocene turbidites (indicative of heating to Tmax > ~120 °C), to partially reset middle Eocene turbidites and no/very weak resetting in the upper Eocene-lower Oligocene molasse (Tmax < ~60 °C). AFT results indicate a late Oligocene-early Miocene cooling event throughout the Axial Zone and Jaca Basin. Paleo-maximum temperatures determined by vitrinite reflectance measurements and Raman spectroscopy of carbonaceous material reach up to ~240 °C at the base of the turbidite succession. Inverse modelling of AFT and vitrinite reflectance data with the QTQt software for key samples show compatibility between vitrinite-derived Tmax and the AFT reset level for most of the samples. However, they also suggest that the highest temperatures determined in the lowermost turbidites correspond to a thermal anomaly rather than burial heating, possibly due to fluid circulation during thrust activity. From these results, we propose a new sequential restoration of the south Pyrenean thrust system propagation and related basin evolution.
ISSN: 0278-7407

insu-01312746
https://hal-insu.archives-ouvertes.fr/insu-01312746
https://hal-insu.archives-ouvertes.fr/insu-01312746/document
https://hal-insu.archives-ouvertes.fr/insu-01312746/file/Labaume_et_al-2016-Tectonics.pdf
DOI : 10.1002/2016TC004192

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : Combined petrographic study and apatite fission track analysis (apatite FTA) across the Gres d'Annot basin document maximum temperatures reached by this turbiditic sandstone formation, from around 60 degrees C at the SW basin margin up to around 200 degrees C below the Penninic frontal thrust, in relation to burial below the front of Alpine nappes. Increasing diagenetic grade across the basin is primarily expressed by the development of silica transfer by pressure solution and correlated porosity loss. We infer the nappe thickness profile, from the nappe front in the SW up to around 8-10 km in the NE. Apatite FTA dates exhumation of the Gres d'Annot during the Late Miocene, in relation to thrusting of the underlying Argentera and Barrot Palaeozoic massifs. This study illustrates the influence of thrust front propagation on foreland basin diagenesis and exhumation, and highlights potential implications for the evolution of sediment reservoir properties in this context.
ISSN: 0954-4879

hal-00411860
https://hal.archives-ouvertes.fr/hal-00411860
DOI : 10.1111/j.1365-3121.2008.00793.x

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Located on the margin of the west Alboran basin, the Gibraltar Arc (Betic-Rif mountain belt) displays post-Pliocene vertical movements evidenced by uplifted marine sedimentary basins and marine terraces. Quantification of vertical movements is an important clue to understand the origin of present-day relief generation in the Betic-Rif mountain chain together with the causes of the Messinian Salinity Crisis. In this paper, we present the results of a pluridisciplinary study combining an analysis of low temperature thermochronology and Pliocene basins evolution to constrain the exhumation history and surface uplift of internals units of the Rif belt (Northern Morocco). The mean (U-Th)/He apatite ages obtained from 11 samples are comprised between 14.1 and 17.8 Ma and display a wide dispersion, which could be explained by a great variability of apatite chemistries in the analyzed samples. No correlations between altitude and age have been found along altitudinal profile suggesting a rapid exhumation during this period. Thermal modeling using our (U-Th)/He apatite ages and geochronological data previously obtained in the same area (40Ar/39Ar and K/Ar data on biotite, zircon and apatite fission track) allow us to propose a cooling history. The rocks suffered a rapid cooling at 60-100 °C/Ma between 22.5 and 19 Ma, then cooled to temperatures around 40 °C between 19 and 18 Ma. They were re-heated at around 110 °C between 18 and 15 Ma then rapidly cooled and exhumed to reach the surface temperature at around 13 Ma. The re-heating could be related to a renewal in thrusting and burying of the inner zones. Between 15 and 13 Ma the cooling resumed at a rate of 50 °C/Ma indicating an exhumation rate of 0.8 mm/y considering an average 40 °C/km geothermal gradient. This exhumation may be linked to the extension in the Alboran Sea. Otherwise biostratigraphic and sedimentological analysis of Pliocene basins of the internal Rif provided informations on the more recent events and vertical movements. Pliocene deposits of the Rifian coast represent the passive infilling of palaeo-rias between 5.33 and 3.8 Ma. The whole coastal area was uplifted at slow average rates (0.01-0.03 mm/y) in relation with a northeastward tilting of 0.2-0.3° since the Lower-Pliocene. A late Pliocene to present extensional tectonics associated to uplift has been identified all along the coastal ranges of the Internal Zone of the Rif chain. This extension was coeval with the major late Pliocene to Pleistocene extensional episode of the Alboran Sea and appears to be still active nowadays. No significant late Messinian uplift was evidenced, thus calling into question the geodynamic models relating the closure of the marine gateways and the MSC to slab roll back.
ISSN: 0264-3707

hal-01053531
https://hal.archives-ouvertes.fr/hal-01053531
DOI : 10.1016/j.jog.2014.01.006

Éditeur(s) : Paris : Firmin Didot Frères

Droits : Domaine public
Provenance : Archives territoriales de Guyane
Permalien : http://www.manioc.org/patrimon/GAD12001
GAD12001

Éditeur(s) : Paris : Firmin Didot Frères

Droits : Domaine public
Provenance : Archives territoriales de Guyane
Permalien : http://www.manioc.org/patrimon/GAD12002
GAD12002