Bulletin de la Societe Geologique de France最新文献

{"title":"Mesozoic and Cenozoic decapod crustaceans from the Basque-Cantabrian basin (Western Pyrenees): new occurrences and faunal turnovers in the context of basin evolution","authors":"M. López-Horgue, A. Bodego","doi":"10.1051/BSGF/2017180","DOIUrl":"https://doi.org/10.1051/BSGF/2017180","url":null,"abstract":"Twenty-nine new identifications of fossil decapod crustacean remains in the Basque-Cantabrian Basin (Western Pyrenees) spanning from the Jurassic to the Miocene and coming from twenty-four new and five yet known localities are described here for the first time. These remains represent a substantial advance in the knowledge of these faunas and their diversity in this basin, giving an accurate image of the decapod faunal succession. The study includes a taxonomical description and discussion with reference to the known occurrences. Their accurate dating and the environmental ascription have been possible after the analysis of the stratigraphic occurrence in the context of a well-known basinal stratigraphy. This has ultimately permitted a brief analysis of the decapod palaeoecology and faunal turnovers in the context of basin evolution.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"113 1","pages":"14"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79719818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fossil Decapod Crustaceans","authors":"S. Charbonnier","doi":"10.1051/BSGF/2017174","DOIUrl":"https://doi.org/10.1051/BSGF/2017174","url":null,"abstract":"This thematic issue of the BSGF-Earth Sciences Bulletin is linked to the 6th Symposium on Mesozoic and Cenozoic Decapod Crustaceans. This scientific meeting was held on June 2016 at the Paléospace Museum of Villers-sur-Mer, Normandy, France. It was supported by the French Geological Society (SGF), the Center for Research on Palaeobiodiversity and Palaeoenvironments (UMR 7207 CNRS) and the National Museum of Natural History, Paris (MNHN). The organization of a symposium dedicated to the Mesozoic and Cenozoic decapod crustaceans was new for France, but was based on a long standing tradition, which dates back to the pioneer work of Latreille, Desmarest and Milne Edwards. During the meeting, nine sessions were proposed and grouped 25 oral communications and 11 posters. Our esteemed colleague Rodney M. Feldmann (Kent State University) opened the scientific sessions with a talk about the Recent Revolution in Decapod Paleontology and concluded that recent remarkable advances have been the result of an increase in the number of palaeontologists devoted to the study of the decapods. Their efforts, coupled with increasingly sophisticated research promises even more innovations in the future. This special issue groups nine original articles on the main topics discussed during the meeting on the crustaceans: systematics, taxonomy, phylogeny, evolution, palaeoecology, palaeobiology, palaeoenvironment, and palaeobiogeography. For instance, Hyžn y et al. (2017) present a review of the burrowing lobster Axius (Axiidea) in the fossil record with notes on its palaeobiogeography. Regarding the palaeoenvironments, a comparative analysis of the Ypresian crustaceans from the coral-algal environments in north-eastern Italy, and a study on the faunal turnovers in the context of the Mesozoic and Cenozoic evolution of the Basque-Cantabrian Basin (Spain), are proposed by Beschin et al. (2017) and LópezHorgue and Bodego (2017) respectively. The systematic palaeontology groups different scientific papers about erymid","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75370707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New thylacocephalans from the Cretaceous Lagerstätten of Lebanon","authors":"S. Charbonnier, G. Teruzzi, Denis Audo, M. Lasseron, C. Haug, J. Haug","doi":"10.1051/BSGF/2017176","DOIUrl":"https://doi.org/10.1051/BSGF/2017176","url":null,"abstract":"Thylacocephalans (Euarthropoda, Thylacocephala) are characterized by their “bivalved” carapace and three anterior prehensile appendages. It is still not clear how they used to live, or what their evolutionary history is. This study focuses on new thylacocephalans from the Late Cretaceous Konservat-Lagerstatten of Lebanon, which yielded the youngest representatives of the group. Three new genera and species are described in the Cenomanian sublithographic limestones of Hakel and Hadjoula, and two new genera and one new species are described in the Santonian chalky limestones of Sahel Alma. Among the specimens from Hakel and Hadjoula, Paradollocaris vannieri , Thylacocaris schrami and Globulacaris garassinoi are the first reports of thylacocephalans in the Cenomanian of Lebanon. Paradollocaris and Thylacocaris are assigned to Dollocarididae based upon their large optic notches limited by rostral and antero-ventral processes, their hypertrophied eyes, and their posterior notches with dorsal and ventral spines. Moreover, Thylacocaris presents a very peculiar character: an optic notch with two strong optic spines protecting the eye. Globulocaris is assigned to Protozoeidae based upon its small carapace with a distinct dorsal notch anterior to a strong postero-dorsal spine. Among the specimens from Sahel Alma, Keelicaris deborae is a new form of thylacocephalans in the Santonian of Lebanon. It presents a very unusual keel-shaped carapace with terraces and punctuations, and is assigned to Microcarididae. The new genus Hamaticaris , presenting a very peculiar hooked rostrum, is also erected for Protozoea damesi Roger, 1946 (Roger J. 1946. Invertebres des couches a poissons du Cretace superieur du Liban. Memoires de la Societe geologique de France (Nouvelle serie) 51: 5–92). These two species add to the well-known thylacocephalans from Sahel Alma: Pseuderichtus cretaceus Dames, 1886 (Dames W. 1886. Ueber einige Crustaceen aus den Kreideablagerungen des Libanon. Zeitschrift der Deutschen Geologischen Gesellschaft 38: 551–575), Protozoea hilgendorfi Dames, 1886 and Thylacocephalus cymolopos Lange et al. , 2001 (Lange S, Hof CHJ, Schram FR, Steeman FA. 2001. New genus and species from the Cretaceous of Lebanon links the Thylacocephala to the Crustacea. Palaeontology 44 (5): 905–912). The occurrence of such diverse fauna of thylacocephalans markedly increases the diversity of the group during the Late Cretaceous. The diversity and abundance of the Sahel Alma thylacocephalans pose also the problem of causes of their disappearance from the fossil record after the Santonian.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"30 1","pages":"19"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86418249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Polycyclic alpine orogeny in the Rhodope metamorphic complex: the record in migmatites from the Nestos shear zone (N. Greece)","authors":"P. Gautier, V. Bosse, Z. Cherneva, A. Didier, I. Gerdjikov, M. Tiepolo","doi":"10.1051/BSGF/2017195","DOIUrl":"https://doi.org/10.1051/BSGF/2017195","url":null,"abstract":"The Rhodope Metamorphic Complex (RMC) is a high-grade crystalline massif located at the northern margin of the Aegean region. Numerous scenarios have been proposed for the evolution of the RMC during Alpine times. A debated issue is whether there has been a single protracted orogenic cycle since around the mid-Mesozoic or whether Alpine orogeny involved distinct episodes of subduction and crustal accretion. We describe a key outcrop located on the Nestos Shear Zone (NSZ), a major NNE-dipping top-to-SW shear zone characterized by an inverted metamorphic sequence. Structural and petrological data document the existence of two anatectic events. The first event, best preserved in decametric structural lenses, is pre-kinematic with respect to top-to-SW shearing and involved high-temperature “dry” melting. Zircon and monazite LA-ICPMS U-Th-Pb data indicate that this event occurred at ∼140 Ma. The second event is syn-kinematic with respect to top-to-SW shearing and involved lower-temperature water-assisted melting. Zircon and rutile LA-ICPMS U-Pb data indicate that this second event occurred at ∼40 Ma. During ongoing top-to-SW shearing and as late as ∼36 Ma, the rocks from the outcrop were at higher temperatures than the peak temperatures experienced by lower levels of the NSZ. This confirms the existence of the inverted metamorphic sequence and demonstrates that the NSZ was a major thrust at 36–40 Ma. The ∼100 Myr time laps between the two anatectic events encompasses the period from ∼115 to ∼70 Ma characterized by a gap in the geochronological record on the scale of the RMC (the Eastern Rhodope excluded). This ∼45 Myr gap likely reflects a period of tectonic quiescence between the mid-Mesozoic orogen and the Cenozoic one, attesting for polycyclic Alpine orogeny in the RMC. Unlike assumed in several geodynamic scenarios, the Alpine evolution of the RMC did not consist of a single orogenic cycle of Mesozoic age followed by Cenozoic crustal-scale extension triggered by mantle delamination. Polycyclic orogeny has resulted in a two-loop P-T-t path for the hangingwall unit of the NSZ. The Cenozoic P-T paths of this unit and the footwall unit merged while both units were being exhumed, a feature attributed to syn-thrusting extensional spreading of the main mass of the hangingwall unit above the NSZ.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"231 1","pages":"36"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85657307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Smectite as a marker of telogenetic process along structural heterogeneities of sedimentary basin: case study of the Eocene submarine slide surfaces of the Ainsa Basin","authors":"F. Odonne, D. Beaufort, Romain Munck, Laure Bourrières, J. Darrozes","doi":"10.1051/BSGF/2017186","DOIUrl":"https://doi.org/10.1051/BSGF/2017186","url":null,"abstract":"Fluid circulation in sedimentary basins is responsible for the transformation and cementation of mineral grains during diagenesis. Concretions and pipe chimneys are obvious features resulting from such circulation but some transformations in the matrix of rocks, if less spectacular, may lead to pervasive transformations of the sediments. Inherited slide surfaces in the Eocene Ainsa Basin (Spanish Pyrenees) have been chosen to test this hypothesis. In the Sobrarbe delta, the steady mineralogy of marls indicates homogeneity of the sedimentary source. Enrichment of montmorillonite is only observed close to scar surfaces and in the infilling of the scars. Scanning electron microscope (SEM) observation reveals that smectites are formed by in situ replacement of detrital mafic minerals resulting by transformation of detrital minerals under the action of cold sedimentary fluids, lower than 75 °C. The indications of low temperature conditions and local fluid circulation both support a meteoric origin of the fluids postdating the burial history, probably during an exhumation of the basin associated with the tectonic uplift. The higher smectite contents in the infilling of scars and along the unconformities of slide surfaces reveals enhanced circulation of fluids in under-consolidated sediments and the effective fluid circulation pathways along inherited slide surfaces.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"15 1","pages":"22"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82155596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tournaisian (Early Carboniferous) foraminifers of the Kuznetsk Basin (South-West Siberia, Russia)","authors":"C. Colpaert, D. Vachard, C. Monnet, S. Clausen, I. Timokhina, O. Obut, N. Izokh","doi":"10.1051/BSGF/2017003","DOIUrl":"https://doi.org/10.1051/BSGF/2017003","url":null,"abstract":"The Taidon and Fomin formations of the Kuznetsk Basin (SW Siberia, Russia) were sampled in three sections, Old Belovo quarry, Artyshta village and Starobachaty village. The carbonate beds revealed microfacies of bioclastic wackestone and packstone, deposited in the distal parts of inner ramps and the proximal parts of mid ramps. Relatively rare plurilocular foraminifers occur in bioclastic neomicrosparitized wackestone deposited in the shallower parts of the carbonate ramp. The other microfacies only contain the bilocular foraminifer genus Earlandia . The plurilocular foraminifers permit the dating of the lower part of the Taidon Formation and the distinction of a biozone characterized by Tuberendothyra , Pseudoplanoendothyra , and Granuliferella . This local biozone can be correlated with the MFZ4 reference-biozone established in Belgium, which is late Hastarian (i.e., latest early Tournaisian) in age. Conodonts of the upper Siphonodella crenulata Zone in the lower part of Taidon Formation are consistent with this late Hastarian age. The Fomin Formation cannot be directly dated by its foraminifers Earlandia . As it is overlain by previously dated lower Visean beds, the Fomin Formation corresponds to all or part of the entire Ivorian (i.e., late Tournaisian) and of the MFZ5 to MFZ8 biozones. The same uncertainty on the late Tournaisian age exists with the conodonts, which belong to the lower Siphonodella crenulata Zone and isosticha- upper crenulata /typicus/anchoralis-latus zones, respectively. As a taxonomical result, Septabrunsiinoidea n. superfam. is introduced, in order to explain some poorly known lineages of the Tournaisian. Palaeobiogeographically, SW Siberia is proposed as the radiation centre of the Septabrunsiinoidea during the Tournaisian, and especially during the Hastarian, and their migration centre toward three directions: North America, South China and western Tethyan areas.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"24 1","pages":"2-2"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90443319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The pull apart-type Tardets-Mauléon Basin, a key to understand the formation of the Pyrenees","authors":"J. Canérot","doi":"10.1051/BSGF/2017198","DOIUrl":"https://doi.org/10.1051/BSGF/2017198","url":null,"abstract":"Contrary to recent conceptual models, we evidence that the Mauleon Basin does not only result from the Pyrenean tectonic inversion of an aborted Albian rift involving a N-S extreme crust thinning, with related detachment and mantle exhumation. It actually corresponds to an element of this rift system where E-W dominant regional sinistral strike slip faulting between its European and Iberian margins generated as early as the Latest Aptian (Clansayesian) an oblique pull apart-type basin: the Tardets-Sorholus Trough. Then, towards the Late to Latest Albian period, the active transverse, SW-NE oriented, Barlanes and Saison listric faults provided the main crustal thinning leading locally (Urdach) to mantle exhumation. Finally, at the beginning of the Late Cretaceous, the trough widened through transtension motion (N-S distension associated with E-W sinistral strike slip) leading to the creation of the Mauleon Basin. This geodynamic evolution gives to the Mauleon Basin its logical place between the western Bilbao Basin where oceanic crust developed through dominant N-S extension process and the central and eastern north Pyrenean basins where dominant E-W left lateral strike slip then transpressive motion preclude mantle denudation. From the Late to Latest Cretaceous, the inverted motion turning to generalized regional transpression led to the closure of the trough, then, by gradual uplift from east to west, to the formation of the Pyrenean range.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"48 1","pages":"35"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82831848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A mantle origin for sulfates in the unusual \"salty\" Udachnaya-East kimberlite from sulfur abundances, speciation and their relationship with groundmass carbonates","authors":"Elisabeth D’Eyrames, E. Thomassot, Y. Kitayama, A. Golovin, A. Korsakov, D. Ionov","doi":"10.1051/BSGF/2017007","DOIUrl":"https://doi.org/10.1051/BSGF/2017007","url":null,"abstract":"The Udachnaya-East pipe in Yakutia in Siberia hosts a unique dry (serpentine-free) body of hypabyssal kimberlite ( O), associated with a less dry type of kimberlite and a serpentinized kimberlitic breccia. The dry kimberlite is anomalously rich in salts (Na2 O and Cl both up to 6wt%) whereas the slightly less dry and the breccia kimberlite are salt free. Yet the Udachnaya kimberlite is a group-I kimberlite, as is the archetypical kimberlite from Kimberley, South Africa. Samples were studied from the three different types of kimberlite (dry-salty, n=8, non-salty, n=5 and breccia, n=3) regarding their mineralogy, geochemistry, and more specifically their sulfur content. Our results show the salty kimberlite is unprecedentedly rich in sulfur (0.13-0.57wt%) compared to the non-salty kimberlite (0.04-0.12wt%) and the breccia (0.29-0.33wt%). In the salty kimberlite, most of the sulfur is present as sulfates (up to 97% of Stotal ) and is disseminated throughout the groundmass in close association with Na-K-bearing carbonates. Sulfates occur within the crystal structure of these Na-K-bearing carbonates as the replacement of (CO3 ) by (SO3 ) groups, or as Na- and K-rich sulfates (e.g. aphtitalite, (K,Na)3 Na(SO4 )2 ). The associated sulfides are djerfisherite; also Na- and K-rich species. The close association of sulfates and carbonates in these S-rich alkaline rocks suggests that the sulfates crystallized from a mantle-derived magma, a case that has strong implication for the oxygen fugacity of kimberlite magmatism and more generally for the global S budget of the mantle.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"22 1","pages":"6-6"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90937353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Late Jurassic - Early Cretaceous paleoenvironmental evolution of the Transbaikal basins (SE Siberia): implications for the Mongol-Okhotsk orogeny","authors":"M. Jolivet, A. Arzhannikova, A. Frolov, S. Arzhannikov, N. Kulagina, V. Akulova, R. Vassallo","doi":"10.1051/BSGF/2017010","DOIUrl":"https://doi.org/10.1051/BSGF/2017010","url":null,"abstract":"The Late Jurassic - Early Cretaceous tectonic evolution of SE Siberia was marked by the closure of the Mongol-Okhotsk ocean. While this geodynamic event led to compressive deformation and denudation in a wide area encompassing the North-Altay, Sayan and Baikal Patom ranges, it was contemporaneous to widespread extension from the Transbaikal region situated immediately north of the suture zone to the Pacific plate, affecting eastern Mongolia and northeastern China. In this study we review the paleontological and sedimentological data available in the Russian literature and provide new macro-floral and palynological data from the Mesozoic sediments of three Transbaikal basins. These data are used to describe the paleoenvironmental and paleoclimatic evolution of the Transbaikal area in order to assess the topographic evolution of the region in relation with the closure of the Mongol-Okhotsk ocean. We establish that the Transbaikal basins evolved in a continuously extensional tectonic setting from at least the Early-Middle Jurassic to the Early Cretaceous. The associated sedimentary environments are characterized by retrogradation from alluvial fan –braided river dominated systems prevailing during the Early to Middle Jurassic initial opening of the basins to meandering river–lacustrine systems that developed during the Late Jurassic - Early Cretaceous interval. No evidence of high relief topography was found and we conclude that, while compression and denudation occurred in the North Altai, Sayan and Patom ranges, in the Transbaikal region, the docking of the Mongolia-North China continent to Siberia was a “soft collision” event, possibly involving a major strike-slip displacement that did not lead to an orogenic event implying strong compressive deformation, crustal thickening and topography building.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"20 1","pages":"9-9"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89380461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Early to Middle Jurassic history of the southern Siberian continent (Transbaikalia) recorded in sediments of the Siberian Craton: Sm-Nd and U-Pb provenance study","authors":"E. Demonterova, A. Ivanov, E. Mikheeva, A. Arzhannikova, A. Frolov, Sergei G. Arzannikov, N. V. Bryanskiy, L. Pavlova","doi":"10.1051/BSGF/2017009","DOIUrl":"https://doi.org/10.1051/BSGF/2017009","url":null,"abstract":"The deposition of Jurassic continental sedimentary rocks in the southern part of the Siberian continent (Transbaikalia) reflects the intensification of tectonomagmatic processes in this region. The most likely cause of this intensification was associated with the formation and development of the Mongol-Okhotsk orogenic belt. The latter was controlled in its turn by the closure of the Mongol-Okhotsk Ocean, for which the timing of its closure, as well as the formation of a collisional orogeny and its subsequent collapse are still under debate. We address this question by studying sediments of the Irkutsk Basin, which were deposited in a short time span in the Middle Jurassic, most likely during the Aalenian. The Sm-Nd data for bulk-rock sandstones demonstrate that the youngest samples of the Irkutsk Basin are characterized by a prominent contribution from a source within the juvenile crust of the Mongol-Okhotsk orogenic belt. U-Pb detrital zircon ages concur with the Sm-Nd data and show that the amount of material derived from local cratonic sources decreased in time whereas material from the remote Transbaikalian sources increased. Our data provide evidence that mountain growth in Transbaikalia intensified rapidly close to the Early and Middle Jurassic boundary.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"4 1","pages":"8-8"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87068005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}