C. Baudement, B. Arfib, N. Mazzilli, Johan Jouves, T. Lamarque, Y. Guglielmi
This paper aims at characterizing the groundwater flow in a highly dynamic karst aquifer using a global modeling approach based on rainfall and spring discharge time series. The Dardennes aquifer (SE France) was studied as it is used for drinking water supply and it also produces karst flash floods that increase the flood hazard downstream in urban areas. Three years of data were available, including a normal rainy year, a wet year and a dry year. Modeling was performed with the new platform KarstMod, a rainfall-discharge model with calibration tools. The Dardennes aquifer model was structured with three interconnected reservoirs: Epikarst, Matrix, and Conduit. Using this modeling approach, we were able to determine the groundwater hydrograph separation of the karst spring discharge, at the annual scale and at the event scale (flood). This gives insight into the low flow (Matrix) available for the drinking water demand and the fast flow (Conduit) that generates flash floods. In such a dynamic aquifer, part of the water budget cannot be accounted for by water resources as fast flow is not stored within the aquifer and is not available for the drinking water demand. The results were compared with the current groundwater management to determine whether the withdrawal is sustainable. Depending on whether it is a wet or a dry year, the proportion of slow flow ranges from 27 to 61% of the total discharge, respectively. During floods in high water periods, the proportion of quickflow increases drastically up to more than 90% of the spring discharge. In the case of a 300 mm/d simulated Mediterranean rainfall event, the mean daily peak value may reach 74 m3 /s. This discharge can be reduced if the aquifer is previously depleted, which increases the storage within the aquifer. Coupling the geological context and the model results opens up future perspectives for the active management of the karst aquifer.
{"title":"Groundwater management of a highly dynamic karst by assessing baseflow and quickflow with a rainfall-discharge model (Dardennes springs, SE France)","authors":"C. Baudement, B. Arfib, N. Mazzilli, Johan Jouves, T. Lamarque, Y. Guglielmi","doi":"10.1051/BSGF/2017203","DOIUrl":"https://doi.org/10.1051/BSGF/2017203","url":null,"abstract":"This paper aims at characterizing the groundwater flow in a highly dynamic karst aquifer using a global modeling approach based on rainfall and spring discharge time series. The Dardennes aquifer (SE France) was studied as it is used for drinking water supply and it also produces karst flash floods that increase the flood hazard downstream in urban areas. Three years of data were available, including a normal rainy year, a wet year and a dry year. Modeling was performed with the new platform KarstMod, a rainfall-discharge model with calibration tools. The Dardennes aquifer model was structured with three interconnected reservoirs: Epikarst, Matrix, and Conduit. Using this modeling approach, we were able to determine the groundwater hydrograph separation of the karst spring discharge, at the annual scale and at the event scale (flood). This gives insight into the low flow (Matrix) available for the drinking water demand and the fast flow (Conduit) that generates flash floods. In such a dynamic aquifer, part of the water budget cannot be accounted for by water resources as fast flow is not stored within the aquifer and is not available for the drinking water demand. The results were compared with the current groundwater management to determine whether the withdrawal is sustainable. Depending on whether it is a wet or a dry year, the proportion of slow flow ranges from 27 to 61% of the total discharge, respectively. During floods in high water periods, the proportion of quickflow increases drastically up to more than 90% of the spring discharge. In the case of a 300 mm/d simulated Mediterranean rainfall event, the mean daily peak value may reach 74 m3 /s. This discharge can be reduced if the aquifer is previously depleted, which increases the storage within the aquifer. Coupling the geological context and the model results opens up future perspectives for the active management of the karst aquifer.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"17 1","pages":"40"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88319247","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}
N. Sennikov, I. Korovnikov, O. Obut, D. Tokarev, N. V. Novozhilova, T. Danelian
This paper discusses the fossil record, stratigraphy and sedimentary environments of lower Cambrian sequences that crop out in the Salair and Gorny Altai, southern part of western Siberia (Russia).Numerous and well-preserved archaeocyaths and a few small shelly fossils (SSF) have been discovered in carbonate sequences that crop out nearby the Gavrilovka village, Salair. The presence of the Gordonicyathus howelli archaeocyath Zone is established for the first time in this thick sequence of biogenic carbonates, in addition to the Nochoroicyathus mariinskii Zone, which was known previously from the Gavrilovka Formation. Both of these zones are Atdabanian in age. It is likely that accumulation of the Gavrilovka Formation took place in relatively shallow waters, along reef buildups surrounded by lagoons with archaeocyaths.In the Ak-Kaya section of the Gorny Altai, the trilobite species Alacephalus contortus and Poliellaspis rotundata , known previously from the upper Atdabanian, were discovered, only a few meters above horizons bearing lower Botoman trilobites. We may consider that the previously known age range of these two species is slightly longer and should be extended up to the lower Botoman. Alternatively, on the basis of their paleoecological affinity for agitated waters, these trilobites may be interpreted as reworked in lower Botoman strata.
{"title":"The Lower Cambrian of the Salair and Gorny Altai (Siberia) revisited","authors":"N. Sennikov, I. Korovnikov, O. Obut, D. Tokarev, N. V. Novozhilova, T. Danelian","doi":"10.1051/BSGF/2017002","DOIUrl":"https://doi.org/10.1051/BSGF/2017002","url":null,"abstract":"This paper discusses the fossil record, stratigraphy and sedimentary environments of lower Cambrian sequences that crop out in the Salair and Gorny Altai, southern part of western Siberia (Russia).Numerous and well-preserved archaeocyaths and a few small shelly fossils (SSF) have been discovered in carbonate sequences that crop out nearby the Gavrilovka village, Salair. The presence of the Gordonicyathus howelli archaeocyath Zone is established for the first time in this thick sequence of biogenic carbonates, in addition to the Nochoroicyathus mariinskii Zone, which was known previously from the Gavrilovka Formation. Both of these zones are Atdabanian in age. It is likely that accumulation of the Gavrilovka Formation took place in relatively shallow waters, along reef buildups surrounded by lagoons with archaeocyaths.In the Ak-Kaya section of the Gorny Altai, the trilobite species Alacephalus contortus and Poliellaspis rotundata , known previously from the upper Atdabanian, were discovered, only a few meters above horizons bearing lower Botoman trilobites. We may consider that the previously known age range of these two species is slightly longer and should be extended up to the lower Botoman. Alternatively, on the basis of their paleoecological affinity for agitated waters, these trilobites may be interpreted as reworked in lower Botoman strata.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"49 1","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87589510","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}
In France, the conservation of geological heritage has a complex history that dates back to the middle of the 19th century. Two regulatory tools, “Site Classe”, established in 1906, and Natural Reserves, created in 1976, have served to protect geological sites in the past. Nonetheless, these tools are long to implement vis-a-vis to the rapid destruction of geological objects in the French territory. Due to this juridical void, the state created in 2015 two prefectural decrees for the protection of geological sites of interest. These tools allow the Prefect to: (i) determine a departmental list of geological sites of importance; (ii) define appropriate regulations for their conservation through the Prefectural Decree of the Protection of the Geotope (APPG). Their decentralised legal proceedings appear to be easy to administer, as they only require the advice of regional and departmental commissions as well as some local stakeholders. Our article reports the first enactment of the APPG in France, in a peri-urban to urban area, the Yvelines department. By relying on the programmes of Strategy of Creation of Protected metropolitan Areas (SCAP) and the National Inventory of the Geological Heritage (INPG), two geological sites of international value threatened by anthropic activities were selected for the APPG: the Lutetian fossil sites of Grignon and the Ferme de l’Orme. If successfully enacted, the APPG could prove advantageous because it is a tool adapted to the protection of geological objects and to its socio-economic and environmental context. However, after almost two years, the proceedings of the APPG have not been finalised. Optional yet beneficial steps, as well as unforeseen requests, delayed the process considerably. Given that the APPG do not confer protection to the geological sites during this period, their efficacy must be questioned in a fast-evolving region where land pressure is high and geological sites disappear quickly. However, the French juridical system has improved in the recent years in that it encourages Earth Sciences specialists to form part of local consultative instances (CSRPN, CDNPS) and thereby influence the decisions concerning the protection of these highly threatened sites.
在法国，地质遗产的保护有着复杂的历史，可以追溯到19世纪中叶。两个监管工具，1906年建立的“遗址分类”和1976年建立的自然保护区，在过去起到了保护地质遗址的作用。尽管如此，相对于法国领土上地质物体的迅速破坏，这些工具还需要很长时间才能实施。由于这一司法空白，该州于2015年制定了两项县级法令，以保护有兴趣的地质遗址。这些工具使州长能够:(i)确定重要地质遗址的部门清单;(ii)通过《地方地形保护法令》(APPG)制定适当的保护条例。他们分散的法律程序似乎很容易管理，因为他们只需要地区和部门委员会以及一些当地利益相关者的建议。我们的文章报道了APPG在法国的第一个颁布，在城郊到市区的伊夫林省。根据建立都市保护区战略(SCAP)和国家地质遗产清单(INPG)的方案，两个受人类活动威胁的具有国际价值的地质遗址被选为APPG:格里尼翁的Lutetian化石遗址和Ferme de l 'Orme。如果成功实施，APPG将被证明是有利的，因为它是一种适用于保护地质对象及其社会经济和环境背景的工具。然而，经过近两年的时间，APPG的程序尚未最终确定。可选但有益的步骤，以及不可预见的请求，大大延迟了这个过程。鉴于APPG在此期间并未对地质遗址进行保护，在一个土地压力高、地质遗址迅速消失的快速发展地区，其有效性必须受到质疑。然而，法国的司法制度近年来有所改善，因为它鼓励地球科学专家成为地方协商机构(CSRPN、CDNPS)的一部分，从而影响有关保护这些高度受威胁地点的决定。
{"title":"New regulatory tool for the conservation of the geological heritage in France: the Prefectural Decree of the Protection of the Geotope (APPG). Application and feedback in the Yvelines department (Paris basin, Île-de-France)","authors":"E. Auberger, J. Gely, D. Merle","doi":"10.1051/BSGF/2018002","DOIUrl":"https://doi.org/10.1051/BSGF/2018002","url":null,"abstract":"In France, the conservation of geological heritage has a complex history that dates back to the middle of the 19th century. Two regulatory tools, “Site Classe”, established in 1906, and Natural Reserves, created in 1976, have served to protect geological sites in the past. Nonetheless, these tools are long to implement vis-a-vis to the rapid destruction of geological objects in the French territory. Due to this juridical void, the state created in 2015 two prefectural decrees for the protection of geological sites of interest. These tools allow the Prefect to: (i) determine a departmental list of geological sites of importance; (ii) define appropriate regulations for their conservation through the Prefectural Decree of the Protection of the Geotope (APPG). Their decentralised legal proceedings appear to be easy to administer, as they only require the advice of regional and departmental commissions as well as some local stakeholders. Our article reports the first enactment of the APPG in France, in a peri-urban to urban area, the Yvelines department. By relying on the programmes of Strategy of Creation of Protected metropolitan Areas (SCAP) and the National Inventory of the Geological Heritage (INPG), two geological sites of international value threatened by anthropic activities were selected for the APPG: the Lutetian fossil sites of Grignon and the Ferme de l’Orme. If successfully enacted, the APPG could prove advantageous because it is a tool adapted to the protection of geological objects and to its socio-economic and environmental context. However, after almost two years, the proceedings of the APPG have not been finalised. Optional yet beneficial steps, as well as unforeseen requests, delayed the process considerably. Given that the APPG do not confer protection to the geological sites during this period, their efficacy must be questioned in a fast-evolving region where land pressure is high and geological sites disappear quickly. However, the French juridical system has improved in the recent years in that it encourages Earth Sciences specialists to form part of local consultative instances (CSRPN, CDNPS) and thereby influence the decisions concerning the protection of these highly threatened sites.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"72 1","pages":"3"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81804566","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}
This paper shows that a multitemporal, multiscale, and multisource remote sensing dataset represents an efficient tool for studying morphotectonics in seismically active areas, with an application in Siberia. The focus is placed on the use of high resolution imagery including Corona, Orbview 3, Ikonos 2 (available on Google Earth), and Landsat images combined with four different digital elevation models (DEMs) built using various satellite data. DEMs are the version 2 SRTM 3 arc-second and version 3 SRTM 1 arc-second released by USGS, the X-SAR DEM, and the version 2 Aster GDEM.In the specific case of the Gorny Altai, the remote sensing dataset composed of DEMs and satellite images provide relevant evidence of the geomorphological consequences of the 2003 Altai earthquake characterized by large landslides, block tilting, and ground-cracks. Ikonos imagery reveals the en-echelon faults compatible with a dextral strike-skip faulting. Archive satellite data allow us detecting new faults generated by the earthquake, but also the pre-existing fault network, with a specific emphasis on the use of Corona archive from the 1960’s. The best global DEMs (SRTM 1 arc-second and Aster GDEM) are well-correlated. Generally, the Aster GDEM presents a lower horizontal accuracy than the SRTM DEM, whereas the vertical accuracy is relatively similar. In the case of the largest landslide induced by the 2003 Altai earthquake (about 1 km2 ), the comparison of the pre-seismic topographic profile obtained by SRTM and the post-seismic topographic profile obtained by Aster GDEM is of great interest. Following the landslide episode, it allows us defining a zone of depletion and a zone of accumulation. The limit between the hard Palaeozoic rocks (sandstone, etc.) and the loose Quaternary sediments appears clearly as a zone of weakness. Before the 2003 earthquake, a round track was already detected in the Corona images, corresponding either to an old landslide or a precursor stage of the major landslide.More generally, the dextral strike-slip faulting is accompanied by the uplift of the northeastern segment, close to the Chagan Uzun block. In the Kuskunnur-Taltura-Chagan river area, this uplift is revealed by the abnormal elevation of the Kuskunnur river compared to the elevation of the Taltura river. The present geomorphological study is a complement to dendrochronological and radiocarbon dating of earthquake triggered landslides, rockfalls and seismically cut fossil soils.
{"title":"Geomorphic study of seismically active areas using remote sensing data. Case of the Gorny Altai (Siberia) affected by the 2003 Altai earthquake","authors":"J. Deroin, M. Buslov","doi":"10.1051/BSGF/2017012","DOIUrl":"https://doi.org/10.1051/BSGF/2017012","url":null,"abstract":"This paper shows that a multitemporal, multiscale, and multisource remote sensing dataset represents an efficient tool for studying morphotectonics in seismically active areas, with an application in Siberia. The focus is placed on the use of high resolution imagery including Corona, Orbview 3, Ikonos 2 (available on Google Earth), and Landsat images combined with four different digital elevation models (DEMs) built using various satellite data. DEMs are the version 2 SRTM 3 arc-second and version 3 SRTM 1 arc-second released by USGS, the X-SAR DEM, and the version 2 Aster GDEM.In the specific case of the Gorny Altai, the remote sensing dataset composed of DEMs and satellite images provide relevant evidence of the geomorphological consequences of the 2003 Altai earthquake characterized by large landslides, block tilting, and ground-cracks. Ikonos imagery reveals the en-echelon faults compatible with a dextral strike-skip faulting. Archive satellite data allow us detecting new faults generated by the earthquake, but also the pre-existing fault network, with a specific emphasis on the use of Corona archive from the 1960’s. The best global DEMs (SRTM 1 arc-second and Aster GDEM) are well-correlated. Generally, the Aster GDEM presents a lower horizontal accuracy than the SRTM DEM, whereas the vertical accuracy is relatively similar. In the case of the largest landslide induced by the 2003 Altai earthquake (about 1 km2 ), the comparison of the pre-seismic topographic profile obtained by SRTM and the post-seismic topographic profile obtained by Aster GDEM is of great interest. Following the landslide episode, it allows us defining a zone of depletion and a zone of accumulation. The limit between the hard Palaeozoic rocks (sandstone, etc.) and the loose Quaternary sediments appears clearly as a zone of weakness. Before the 2003 earthquake, a round track was already detected in the Corona images, corresponding either to an old landslide or a precursor stage of the major landslide.More generally, the dextral strike-slip faulting is accompanied by the uplift of the northeastern segment, close to the Chagan Uzun block. In the Kuskunnur-Taltura-Chagan river area, this uplift is revealed by the abnormal elevation of the Kuskunnur river compared to the elevation of the Taltura river. The present geomorphological study is a complement to dendrochronological and radiocarbon dating of earthquake triggered landslides, rockfalls and seismically cut fossil soils.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"14 1","pages":"11-11"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78566843","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}
I. Radu, B. Moine, D. Ionov, A. Korsakov, A. Golovin, D. Mikhailenko, J. Cottin
Xenoliths brought up by kimberlite magmas are rare samples of otherwise inaccessible lithospheric mantle. Eclogite xenoliths are found in most cratons and commonly show a range of mineral and chemical compositions that can be used to better understand craton formation. This study focuses on five new kyanite-bearing eclogites from the Udachnaya kimberlite pipe (367±5 Ma). They are fine-to coarse-grained and consist mainly of “cloudy” clinopyroxene (cpx) and garnet (grt). The clinopyroxene is Al,Na-rich omphacite while the garnet is Ca-rich, by contrast to typical bi-mineral (cpx+grt) eclogites that contain Fe- and Mg-rich garnets. The Udachnaya kyanite eclogites are similar in modal and major element composition to those from other cratons (Dharwar, Kaapvaal, Slave, West African). The kyanite eclogites have lower REE concentrations than bi-mineral eclogites and typically contain omphacites with positive Eu and Sr anomalies, i.e. a “ghost plagioclase signature”. Because such a signature can only be preserved in nonmetasomatised samples, we infer that they were present in the protoliths of the eclogites. It follows that subducted oceanic crust is present at the base of the Siberian craton. Similar compositions and textures are also seen in kyanite eclogites from other cratons, which we view as evidence for an Archean, subduction-like formation mechanism related to craton accretion. Thus, contrary to previous work that classifies all kyanite eclogites as type I (IK), metasomatized by carbonatite/kimberlitic fluids, we argue that some of them, both from this work and those from other cratons, belong to the non-metasomatized type II (IIB). The pristine type IIB is the nearest in composition to protoliths of mantle eclogites because it contains no metasomatic enrichments.
{"title":"Kyanite-bearing eclogite xenoliths from the Udachnaya kimberlite, Siberian craton, Russia","authors":"I. Radu, B. Moine, D. Ionov, A. Korsakov, A. Golovin, D. Mikhailenko, J. Cottin","doi":"10.1051/BSGF/2017008","DOIUrl":"https://doi.org/10.1051/BSGF/2017008","url":null,"abstract":"Xenoliths brought up by kimberlite magmas are rare samples of otherwise inaccessible lithospheric mantle. Eclogite xenoliths are found in most cratons and commonly show a range of mineral and chemical compositions that can be used to better understand craton formation. This study focuses on five new kyanite-bearing eclogites from the Udachnaya kimberlite pipe (367±5 Ma). They are fine-to coarse-grained and consist mainly of “cloudy” clinopyroxene (cpx) and garnet (grt). The clinopyroxene is Al,Na-rich omphacite while the garnet is Ca-rich, by contrast to typical bi-mineral (cpx+grt) eclogites that contain Fe- and Mg-rich garnets. The Udachnaya kyanite eclogites are similar in modal and major element composition to those from other cratons (Dharwar, Kaapvaal, Slave, West African). The kyanite eclogites have lower REE concentrations than bi-mineral eclogites and typically contain omphacites with positive Eu and Sr anomalies, i.e. a “ghost plagioclase signature”. Because such a signature can only be preserved in nonmetasomatised samples, we infer that they were present in the protoliths of the eclogites. It follows that subducted oceanic crust is present at the base of the Siberian craton. Similar compositions and textures are also seen in kyanite eclogites from other cratons, which we view as evidence for an Archean, subduction-like formation mechanism related to craton accretion. Thus, contrary to previous work that classifies all kyanite eclogites as type I (IK), metasomatized by carbonatite/kimberlitic fluids, we argue that some of them, both from this work and those from other cratons, belong to the non-metasomatized type II (IIB). The pristine type IIB is the nearest in composition to protoliths of mantle eclogites because it contains no metasomatic enrichments.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"80 1","pages":"7-7"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72673387","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}
B. Vendeville, Tang Pengcheng, F. Graveleau, Hu Shao-ying, Xin Wang
We conducted a series of analogue experiments on shortening of a brittle cover (dry sand) above a deep, thin, frictional detachment (glass microbeads). In some experiments, the cover was homogeneous, entirely brittle. In others, there was a thin viscous silicone layer (representing salt) embedded at mid height into the cover, and initially located in the foreland of the fold-and-thrust belt. Our goal was to determine whether or not the presence of such a decollement in the cover could have an impact on the mechanics and kinematics of the underlying subsalt thrusts. Results confirm that, once the front of the foldbelt reached the hinterland salt pinch out, the kinematics of the deeper belt changed drastically: its front stopped propagating forward, and most of the subsequent shortening was accommodated by a larger-than-normal slip along the foremost and youngest deep thrust, while, above the salt decollement , the deformation front propagated very fast, creating a very low surface slope. We hypothesize that it is the gentle sub-critical surface slope associated with rocksalt’s low viscosity that prevents the build-up of an overall surface slope steep enough to allow the underlying, deep foldbelt to continue propagating forward. Finally, one experiment in which only one half of the width of the model comprised an interbedded viscous decollement has shown that the kinematics of the deep thrust was affected even in the adjacent salt-free domain.
{"title":"How the presence of a salt décollement in the sedimentary cover influences the behavior of subsalt thrusts in fold-and-thrust belts","authors":"B. Vendeville, Tang Pengcheng, F. Graveleau, Hu Shao-ying, Xin Wang","doi":"10.1051/BSGF/2017202","DOIUrl":"https://doi.org/10.1051/BSGF/2017202","url":null,"abstract":"We conducted a series of analogue experiments on shortening of a brittle cover (dry sand) above a deep, thin, frictional detachment (glass microbeads). In some experiments, the cover was homogeneous, entirely brittle. In others, there was a thin viscous silicone layer (representing salt) embedded at mid height into the cover, and initially located in the foreland of the fold-and-thrust belt. Our goal was to determine whether or not the presence of such a decollement in the cover could have an impact on the mechanics and kinematics of the underlying subsalt thrusts. Results confirm that, once the front of the foldbelt reached the hinterland salt pinch out, the kinematics of the deeper belt changed drastically: its front stopped propagating forward, and most of the subsequent shortening was accommodated by a larger-than-normal slip along the foremost and youngest deep thrust, while, above the salt decollement , the deformation front propagated very fast, creating a very low surface slope. We hypothesize that it is the gentle sub-critical surface slope associated with rocksalt’s low viscosity that prevents the build-up of an overall surface slope steep enough to allow the underlying, deep foldbelt to continue propagating forward. Finally, one experiment in which only one half of the width of the model comprised an interbedded viscous decollement has shown that the kinematics of the deep thrust was affected even in the adjacent salt-free domain.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"13 1","pages":"37"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86670818","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}
The idea for this thematic issue was introduced at the end of the Earth Sciences conference of the French-Siberian Centre for Research and Training (FSCRT) that took place on August 21st, 2014 in Barnaul (Siberia; fig. 1). The meeting was followed by a geological fieldtrip, led by Dr. Michail Buslov (Novosibirsk), which allowed most of the participants to appreciate the geology of the mountainous region of Gorny-Altai. Fig. 1 Participants to the Barnaul meeting, from left to right: Michail Buslov (Novosibirsk), Emilie Thomassot (Nancy), Elisabeth d’Eyrames (Nancy), Yumi Kitayama (Nancy), Anton Kolesnikov (Novosibirsk & Lille), Gauthier Hainault (Lille), Igor Kosenko (Novosibirsk), Clementine Colpaert (Lille & Novosibirsk), Yana Bazhenova (Tomsk), Igor Korovnikov (Novosibirsk), Olga Obut (Novosibirsk), Alexey Tishkin (Barnaul), Taniel Danelian (Lille), Jean-Paul Deroin (Reims), Cesar Witt (Lille), Maxime Gaumeaux (Reims), Claude Monnet (Lille), Dmitriy Grazhdankin (Novosibirsk). The French-Siberian Centre was set up following the signature in September 2012 of an agreement between the Centre National de la Recherche Scientifique (CNRS) and a consortium of 19 French Universities, on one side and the Siberian Branch of the Russian Academy of Sciences (SB-RAS) and a consortium of 13 Siberian Universities, on the other side. It involved a call for joint French-Russian collaborative proposals with the objective to enhance or initiate scientific collaboration between French and Siberian Universities and/or Research Institutes. We were successful with a multidisciplinary proposal in Earth Sciences (PI T. Danelian and N.V. Sennikov) entitled “ Geodynamic and paleoecosystem evolution in Siberia ”, funded by the French Ministry of Education, Higher Education and Research and the Siberian Branch of the Russian Academy of Sciences (2013–2014). The two main objectives of our project were: 1. to strengthen or initiate research collaboration between 5 CNRS laboratories hosted in 5 different French Universities (Lille 1, Rennes 1, St Etienne, Chambery, Paris 6) and 3 …
{"title":"An introduction to the special issue of the BSGF - Insights into the geology and paleontology of Siberia from French-Siberian collaboration in Earth Sciences","authors":"T. Danelian, M. Jolivet, D. Ionov","doi":"10.1051/BSGF/2017001","DOIUrl":"https://doi.org/10.1051/BSGF/2017001","url":null,"abstract":"The idea for this thematic issue was introduced at the end of the Earth Sciences conference of the French-Siberian Centre for Research and Training (FSCRT) that took place on August 21st, 2014 in Barnaul (Siberia; fig. 1). The meeting was followed by a geological fieldtrip, led by Dr. Michail Buslov (Novosibirsk), which allowed most of the participants to appreciate the geology of the mountainous region of Gorny-Altai. Fig. 1 Participants to the Barnaul meeting, from left to right: Michail Buslov (Novosibirsk), Emilie Thomassot (Nancy), Elisabeth d’Eyrames (Nancy), Yumi Kitayama (Nancy), Anton Kolesnikov (Novosibirsk & Lille), Gauthier Hainault (Lille), Igor Kosenko (Novosibirsk), Clementine Colpaert (Lille & Novosibirsk), Yana Bazhenova (Tomsk), Igor Korovnikov (Novosibirsk), Olga Obut (Novosibirsk), Alexey Tishkin (Barnaul), Taniel Danelian (Lille), Jean-Paul Deroin (Reims), Cesar Witt (Lille), Maxime Gaumeaux (Reims), Claude Monnet (Lille), Dmitriy Grazhdankin (Novosibirsk). The French-Siberian Centre was set up following the signature in September 2012 of an agreement between the Centre National de la Recherche Scientifique (CNRS) and a consortium of 19 French Universities, on one side and the Siberian Branch of the Russian Academy of Sciences (SB-RAS) and a consortium of 13 Siberian Universities, on the other side. It involved a call for joint French-Russian collaborative proposals with the objective to enhance or initiate scientific collaboration between French and Siberian Universities and/or Research Institutes. We were successful with a multidisciplinary proposal in Earth Sciences (PI T. Danelian and N.V. Sennikov) entitled “ Geodynamic and paleoecosystem evolution in Siberia ”, funded by the French Ministry of Education, Higher Education and Research and the Siberian Branch of the Russian Academy of Sciences (2013–2014). The two main objectives of our project were: 1. to strengthen or initiate research collaboration between 5 CNRS laboratories hosted in 5 different French Universities (Lille 1, Rennes 1, St Etienne, Chambery, Paris 6) and 3 …","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"3 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87776728","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}
Northeast Asia is the greatest area in the world where continental extension is documented, from Transbaikalia to the Pacific coast. The major extensional events occurred during Late Jurassic - Early Cretaceous times and are marked by rift basins filled with continental sediments and volcanic rocks, metamorphic core complexes, and extensive magmatism. Here, we review the different types of extensional structures in the region using our own examples from eastern Mongolia, including new data from the Gobi area, and those previously documented in the adjacent regions. We further provide a compilation of available ages, including new data from Transbaikalia, to constrain crustal stretching throughout northeastern Asia. Our analysis shows that extension is not correlated to orogenic collapse, but is coeval with two major changes in plate kinematics that occurred at ca. 140 Ma: the closure of the Mongol-Okhotsk Ocean and a major change in the subduction direction of the Izanagi oceanic plate towards northeast Asia, from high-angle to low-angle convergence. These major changes in plate kinematics combined with an abnormally hot pre-extension state of the continental lithosphere might have triggered spreading in northeast Asia.
{"title":"Late Jurassic – Early Cretaceous continental extension in northeast Asia – Relationships to plate kinematics","authors":"Yannick Daoudène, D. Gapais, J. Cogné, G. Ruffet","doi":"10.1051/BSGF/2017011","DOIUrl":"https://doi.org/10.1051/BSGF/2017011","url":null,"abstract":"Northeast Asia is the greatest area in the world where continental extension is documented, from Transbaikalia to the Pacific coast. The major extensional events occurred during Late Jurassic - Early Cretaceous times and are marked by rift basins filled with continental sediments and volcanic rocks, metamorphic core complexes, and extensive magmatism. Here, we review the different types of extensional structures in the region using our own examples from eastern Mongolia, including new data from the Gobi area, and those previously documented in the adjacent regions. We further provide a compilation of available ages, including new data from Transbaikalia, to constrain crustal stretching throughout northeastern Asia. Our analysis shows that extension is not correlated to orogenic collapse, but is coeval with two major changes in plate kinematics that occurred at ca. 140 Ma: the closure of the Mongol-Okhotsk Ocean and a major change in the subduction direction of the Izanagi oceanic plate towards northeast Asia, from high-angle to low-angle convergence. These major changes in plate kinematics combined with an abnormally hot pre-extension state of the continental lithosphere might have triggered spreading in northeast Asia.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"11 1","pages":"10-10"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89490028","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}
A. Kolesnikov, T. Danelian, M. Gommeaux, A. Maslov, D. Grazhdankin
In the course of studying modern halotolerant microbial mats in salterns near the village of Kervalet, western France, we observed fanning-out and curved series of macroscopic ridges on the surface of a newly formed biofilm. The structure resembles the late Ediacaran fossil Arumberia which is globally distributed in Australia, Avalonia, Baltica, Siberia and India, always confined to intertidal and delta-plain settings subject to periodic desiccation or fluctuating salinity. Although the origin of the structure observed in modern microbial mats remains enigmatic, wrinkled and rugose variants of microbial biofilms in general exhibit increased levels of resistance to several environmental stresses. By analogy, the fossil Arumberia could be interpreted as a microbial mat morphotype (the “Arumberia” morph) developed in response to environmental perturbations in terminal Ediacaran shallow marine basins. If environmental conditions are likely to be responsible for the formation of Arumberia , it is not that a specific biological community has survived since the Ediacaran – it is that the biological response of microbial communities that manifested itself quite commonly in certain terminal Ediacaran and early Cambrian environments can still be found (seemingly in much more restricted settings) today.
{"title":"Arumberiamorph structure in modern microbial mats: implications for Ediacaran palaeobiology","authors":"A. Kolesnikov, T. Danelian, M. Gommeaux, A. Maslov, D. Grazhdankin","doi":"10.1051/BSGF/2017006","DOIUrl":"https://doi.org/10.1051/BSGF/2017006","url":null,"abstract":"In the course of studying modern halotolerant microbial mats in salterns near the village of Kervalet, western France, we observed fanning-out and curved series of macroscopic ridges on the surface of a newly formed biofilm. The structure resembles the late Ediacaran fossil Arumberia which is globally distributed in Australia, Avalonia, Baltica, Siberia and India, always confined to intertidal and delta-plain settings subject to periodic desiccation or fluctuating salinity. Although the origin of the structure observed in modern microbial mats remains enigmatic, wrinkled and rugose variants of microbial biofilms in general exhibit increased levels of resistance to several environmental stresses. By analogy, the fossil Arumberia could be interpreted as a microbial mat morphotype (the “Arumberia” morph) developed in response to environmental perturbations in terminal Ediacaran shallow marine basins. If environmental conditions are likely to be responsible for the formation of Arumberia , it is not that a specific biological community has survived since the Ediacaran – it is that the biological response of microbial communities that manifested itself quite commonly in certain terminal Ediacaran and early Cambrian environments can still be found (seemingly in much more restricted settings) today.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"36 1","pages":"5-5"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88416352","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}
Samuel Seuru, S. Leshchinskiy, P. Auguste, N. Fedyaev
Detailed paleobiological and taphonomic analyses were carried out on the bone accumulations discovered during the 2014 excavations at the Krasnoyarskaya Kurya site, southeastern part of western Siberia (Russia). The fossiliferous site contains three bone-bearing horizons. Mammal remains are rare in the upper level and they were not found during the 2014 excavation. The middle and lower levels yielded exclusively remains of the woolly mammoth, Mammuthus primigenius . The middle level (stratigraphic layer 5) is a result of an in situ accumulation in alluvial sediments. At least three individuals are identified: a juvenile ( 43 years old in AEY) of 2.9 m of shoulder height and 3.8 t. Their remains were buried in conditions similar to those of a floodplain scroll/natural levee or an islet. Bones stayed on the subsurface for a long time, allowing thus carnivores to reach them easily. The lower level (stratigraphic layer 6) is composed of at least four animals: two juveniles ( 11-13 years old in AEY). The material only enables to determine that one juvenile is 1.5 m at shoulder height and weighs ca. 610 kg, while a young adult should have a body mass of ca. 1,600 kg. No human artefacts or any cut-marks on bones were found in either of these two levels during the 2014 excavation. However, the excavations carried out during the years 2007 to 2010 had allowed the discovery of Palaeolithic artefacts in the lower level, which was formed in alluvial-lacustrine conditions. This indicates that humans had visited this a priori in situ mammoth assemblage. It is likely that at the beginning of spring, the oxbow lake had trapped woolly mammoths. Humans and carnivores had then sorted out and taken away any useful remains. Radiocarbon dating indicates that the mammoth died at the early phase of the Last Glacial Maximum, at about 14 C – 20 000 BP (~ 24 000 years cal BP). Isotopic analyses of the collagen from the mammoth remains argue that the animal was living at the time in a steppe landscape, which was dominated by grass-like vegetation.
2014年在俄罗斯西伯利亚西部东南部的Krasnoyarskaya Kurya遗址发掘中发现的骨骼堆积进行了详细的古生物学和地学分析。这个化石遗址包含三个有骨头的地层。哺乳动物的遗骸在上层非常罕见，在2014年的挖掘中没有被发现。中间和较低的层次只留下了长毛猛犸象(Mammuthus primigenius)的遗骸。中层(地层第5层)是冲积沉积物原位堆积的结果。至少确认了三个个体:一个肩高2.9米、3.8吨的少年(AEY 43岁)。他们的遗体被埋在类似于洪泛区卷卷/天然堤坝或小岛的条件下。骨头在地下停留了很长时间，因此食肉动物可以很容易地接触到它们。下层(第6层)至少有4只动物:2只幼兽(AEY地区11-13岁)。该材料只能确定一只幼龙的肩高为1.5米，体重约610公斤，而一只年轻的成年龙的体重应该在1600公斤左右。在2014年的挖掘中，在这两层都没有发现人类文物或骨头上的任何切割痕迹。然而，在2007年至2010年进行的挖掘工作中，在较低的水平发现了旧石器时代的文物，这些文物形成于冲积-湖泊条件下。这表明人类曾先验地造访过这个猛犸象群。很可能在初春的时候，牛轭湖就困住了长毛象。然后，人类和食肉动物将所有有用的遗骸分类并带走。放射性碳测年表明，猛犸象死于末次盛冰期早期，约14c - 20000 BP (~ 24000 calbp)。对猛犸象遗骸胶原蛋白的同位素分析表明，猛犸象当时生活在草原上，那里主要是草状植被。
{"title":"Woolly mammoth and Man at Krasnoyarskaya Kurya site, West Siberian Plain, Russia (excavation results of 2014)","authors":"Samuel Seuru, S. Leshchinskiy, P. Auguste, N. Fedyaev","doi":"10.1051/BSGF/2017005","DOIUrl":"https://doi.org/10.1051/BSGF/2017005","url":null,"abstract":"Detailed paleobiological and taphonomic analyses were carried out on the bone accumulations discovered during the 2014 excavations at the Krasnoyarskaya Kurya site, southeastern part of western Siberia (Russia). The fossiliferous site contains three bone-bearing horizons. Mammal remains are rare in the upper level and they were not found during the 2014 excavation. The middle and lower levels yielded exclusively remains of the woolly mammoth, Mammuthus primigenius . The middle level (stratigraphic layer 5) is a result of an in situ accumulation in alluvial sediments. At least three individuals are identified: a juvenile ( 43 years old in AEY) of 2.9 m of shoulder height and 3.8 t. Their remains were buried in conditions similar to those of a floodplain scroll/natural levee or an islet. Bones stayed on the subsurface for a long time, allowing thus carnivores to reach them easily. The lower level (stratigraphic layer 6) is composed of at least four animals: two juveniles ( 11-13 years old in AEY). The material only enables to determine that one juvenile is 1.5 m at shoulder height and weighs ca. 610 kg, while a young adult should have a body mass of ca. 1,600 kg. No human artefacts or any cut-marks on bones were found in either of these two levels during the 2014 excavation. However, the excavations carried out during the years 2007 to 2010 had allowed the discovery of Palaeolithic artefacts in the lower level, which was formed in alluvial-lacustrine conditions. This indicates that humans had visited this a priori in situ mammoth assemblage. It is likely that at the beginning of spring, the oxbow lake had trapped woolly mammoths. Humans and carnivores had then sorted out and taken away any useful remains. Radiocarbon dating indicates that the mammoth died at the early phase of the Last Glacial Maximum, at about 14 C – 20 000 BP (~ 24 000 years cal BP). Isotopic analyses of the collagen from the mammoth remains argue that the animal was living at the time in a steppe landscape, which was dominated by grass-like vegetation.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"6 1","pages":"4-4"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78616580","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：