Pub Date : 2015-10-01DOI: 10.2113/GSSGFBULL.186.6.451
A. Touil, M. Hibti
L’article de Berrada et al. [2015] decrit les zonations metasomatiques liees aux skarns d’Azegour (Haut-Atlas, Maroc). Les relations chronologiques et reactionnelles entre les differents stades hydrothermaux ainsi que leurs relations avec les mineralisations ne sont pas bien illustres. Nous proposons par le present commentaire des elements de reponse a ces remarques en apportant eventuellement de nouvelles donnees permettant une meilleure comprehension des alterations hydrothermales et leur role dans la mise en place et la formation des mineralisations liees aux skarns d’Azegour. Les alterations hydrothermales a l’origine des skarns d’Azegour, caracterisent cinq stades hydrothermaux [El Khalile et al. , 2014 et Touil et al. , 2014]: 1 – Berrada et al. [2015] considerent que les bancs a wollastonite alternent avec les grenatites. En effet, l’allure sur le terrain laisse penser a des recurrences a wollastonite-grenatite. En revanche, l’observation detaillee sur cassure fraiche et au microscope montre que le contact entre les grenatites du stade III et les wollastonitites du stade II est diffus et progressif. Localement, les zones a wollastonite s’anastomosent avec les zones a grenatite (fig. 3– photo C). Dans le stade II, la wollastonite peut etre seule ou associee a la vesuvianite brune (fig. 2). Elle se developpe directement sur le marbre ou sur le pyroxene qui peut etre reduit …
Berrada等人[2015]的文章描述了与skarns d’Azegour(摩洛哥高阿特拉斯)相关的交代带。不同热液相之间的时间和反应关系及其与成矿的关系尚不清楚。在本文的评论中，我们提出了对这些评论的答案，并可能提供新的数据，以便更好地理解热液蚀变及其在与阿泽古尔skarns有关的矿化的建立和形成中的作用。azegour skarns起源的热液蚀变特征为5个热液蚀变阶段[El Khalile et al.， 2014 and Touil et al.， 2014]:1 - Berrada et al.[2015]认为硅灰石层与石榴石交替。事实上，球场上的速度让人联想到沃拉斯石-石榴石的复发。另一方面，对新裂缝和显微镜的详细观察表明，III期石榴石和II期硅石之间的接触是扩散的和渐进的。在局部，wollastonite带与石榴石带吻合(图3 -图C)。在第二阶段，wollastonite可以单独存在，也可以与棕色的vesuvianite联合存在(图2)。它直接生长在大理石或可还原的辉石上。
{"title":"Commentaire sur l’article “Le skarn Mo-W-Cu à grenat, wollastonite, pyroxène et vésuvianite d’Azegour (Haut-Atlas, Maroc)” de Berrada et al. (Bull. Soc. géol. France, 2015, t. 186, n° 1, pp. 21–34)","authors":"A. Touil, M. Hibti","doi":"10.2113/GSSGFBULL.186.6.451","DOIUrl":"https://doi.org/10.2113/GSSGFBULL.186.6.451","url":null,"abstract":"L’article de Berrada et al. [2015] decrit les zonations metasomatiques liees aux skarns d’Azegour (Haut-Atlas, Maroc). Les relations chronologiques et reactionnelles entre les differents stades hydrothermaux ainsi que leurs relations avec les mineralisations ne sont pas bien illustres.\u0000\u0000Nous proposons par le present commentaire des elements de reponse a ces remarques en apportant eventuellement de nouvelles donnees permettant une meilleure comprehension des alterations hydrothermales et leur role dans la mise en place et la formation des mineralisations liees aux skarns d’Azegour.\u0000\u0000Les alterations hydrothermales a l’origine des skarns d’Azegour, caracterisent cinq stades hydrothermaux [El Khalile et al. , 2014 et Touil et al. , 2014]:\u0000\u00001 – Berrada et al. [2015] considerent que les bancs a wollastonite alternent avec les grenatites. En effet, l’allure sur le terrain laisse penser a des recurrences a wollastonite-grenatite. En revanche, l’observation detaillee sur cassure fraiche et au microscope montre que le contact entre les grenatites du stade III et les wollastonitites du stade II est diffus et progressif. Localement, les zones a wollastonite s’anastomosent avec les zones a grenatite (fig. 3– photo C).\u0000\u0000Dans le stade II, la wollastonite peut etre seule ou associee a la vesuvianite brune (fig. 2). Elle se developpe directement sur le marbre ou sur le pyroxene qui peut etre reduit …","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"21 1","pages":"451-453"},"PeriodicalIF":0.0,"publicationDate":"2015-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88998855","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}
Pub Date : 2015-10-01DOI: 10.2113/GSSGFBULL.186.6.413
V. Zeitoun, Winayalai Chinnawut, R. Debruyne, P. Auetrakulvit
The fossil record is assumed to point to different ecologies, extinction times and ’last stands’ in different regions of the world for Proboscideans, and in some regions, human-proboscidean interaction may theoretically have covered a time span of up to two million years. This paper focuses on the Early Pleistocene of China and Southeast Asia, where the Ailuropoda-Stegodon complex is considered to be a chronologically significant faunal association in the following period. However, the stratigraphic contexts of these local faunal complexes require clarification. Indeed, after one century of research to establish a regional biostratigraphy and in spite of the recomandations provided in the 1980s, many geochronological surveys were undertaken in the 1990s but many problems still exist. Thus, as a first step, taking into consideration the uncertain nature of the geological, taphonomic and chronological data, this paper proposes a critical review of the validity of the associations of Stegodon and Elephas during the Early Pleistocene for this geographical area. Finally, it was necessary to expose what are the current problems before to try to solve them rather than to pursue an unfounded headlong rush. This review concludes that very few reliable data are available and that high-level resolution (MIS) palaeoecological modelization is almost impossible, severely hindering any discussions of strict interaction between humans and proboscideans.
{"title":"Assessing the occurrence of Stegodon and Elephas in China and Southeast Asia during the Early Pleistocene","authors":"V. Zeitoun, Winayalai Chinnawut, R. Debruyne, P. Auetrakulvit","doi":"10.2113/GSSGFBULL.186.6.413","DOIUrl":"https://doi.org/10.2113/GSSGFBULL.186.6.413","url":null,"abstract":"The fossil record is assumed to point to different ecologies, extinction times and ’last stands’ in different regions of the world for Proboscideans, and in some regions, human-proboscidean interaction may theoretically have covered a time span of up to two million years. This paper focuses on the Early Pleistocene of China and Southeast Asia, where the Ailuropoda-Stegodon complex is considered to be a chronologically significant faunal association in the following period. However, the stratigraphic contexts of these local faunal complexes require clarification. Indeed, after one century of research to establish a regional biostratigraphy and in spite of the recomandations provided in the 1980s, many geochronological surveys were undertaken in the 1990s but many problems still exist. Thus, as a first step, taking into consideration the uncertain nature of the geological, taphonomic and chronological data, this paper proposes a critical review of the validity of the associations of Stegodon and Elephas during the Early Pleistocene for this geographical area. Finally, it was necessary to expose what are the current problems before to try to solve them rather than to pursue an unfounded headlong rush. This review concludes that very few reliable data are available and that high-level resolution (MIS) palaeoecological modelization is almost impossible, severely hindering any discussions of strict interaction between humans and proboscideans.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"245 1","pages":"413-427"},"PeriodicalIF":0.0,"publicationDate":"2015-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76767054","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}
Pub Date : 2015-10-01DOI: 10.2113/GSSGFBULL.186.6.399
J. Ferrière, F. Chanier, P. Baumgartner, P. Dumitrică, M. Caridroit, V. Bout‐Roumazeilles, F. Graveleau, T. Danelian, S. Ventalon
Major ophiolitic thrust sheets are widespread within the internal Hellenides, particularly in the Pelagonian domain (Greece and Albania). The ophiolitic sheets are notably well exposed in western Othris mountains of continental Greece. In that area, the structural stacking of oceanic nappes obducted in the Jurassic is particularly well constrained. New sedimentological and structural data from recently studied outcrops, together with new micro-paleontological data, allow to reconsider the architecture of the ophiolitic nappes and their evolution in the Othris mountains. Our new data set includes notably the description of a Mid-Late Jurassic sedimentary succession, from basal litharenites and radiolarites to syn-obduction melange, on top of the uppermost Mega Isoma ophiolitic Unit. These results are crucial in the perspective of constraining the Jurassic contractional evolution of the Maliac Ocean from the beginning of the subduction and intra-oceanic obduction to the final obduction on the Pelagonian continental crust. Another major result concerns the dating of primary conformable series of Middle and Late Triassic age on top of the pillow-lavas of the Fourka unit. Since this lava unit, with MORB affinities, is one of the syn-obduction Jurassic nappes, we propose that this very large Fourka nappe represents the major reference unit of the initial (Triassic) Maliac oceanic crust.
{"title":"The evolution of the Triassic-Jurassic Maliac oceanic lithosphere: insights from the supra-ophiolitic series of Othris (continental Greece)","authors":"J. Ferrière, F. Chanier, P. Baumgartner, P. Dumitrică, M. Caridroit, V. Bout‐Roumazeilles, F. Graveleau, T. Danelian, S. Ventalon","doi":"10.2113/GSSGFBULL.186.6.399","DOIUrl":"https://doi.org/10.2113/GSSGFBULL.186.6.399","url":null,"abstract":"Major ophiolitic thrust sheets are widespread within the internal Hellenides, particularly in the Pelagonian domain (Greece and Albania). The ophiolitic sheets are notably well exposed in western Othris mountains of continental Greece. In that area, the structural stacking of oceanic nappes obducted in the Jurassic is particularly well constrained. New sedimentological and structural data from recently studied outcrops, together with new micro-paleontological data, allow to reconsider the architecture of the ophiolitic nappes and their evolution in the Othris mountains. Our new data set includes notably the description of a Mid-Late Jurassic sedimentary succession, from basal litharenites and radiolarites to syn-obduction melange, on top of the uppermost Mega Isoma ophiolitic Unit. These results are crucial in the perspective of constraining the Jurassic contractional evolution of the Maliac Ocean from the beginning of the subduction and intra-oceanic obduction to the final obduction on the Pelagonian continental crust. Another major result concerns the dating of primary conformable series of Middle and Late Triassic age on top of the pillow-lavas of the Fourka unit. Since this lava unit, with MORB affinities, is one of the syn-obduction Jurassic nappes, we propose that this very large Fourka nappe represents the major reference unit of the initial (Triassic) Maliac oceanic crust.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"11 1","pages":"399-411"},"PeriodicalIF":0.0,"publicationDate":"2015-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84273180","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}
Pub Date : 2015-10-01DOI: 10.2113/GSSGFBULL.186.6.429
L. Beccaletto, L. Capar, O. Serrano, S. Marc
Stephanian to Permian post-orogenic basins (SPB) outcrop in several limited locations in and around the present-day French Variscan basement. Little is known about their subsurface occurrences beneath the post-depositional sedimentary cover. Our work intends to decipher the structural evolution of the hidden SPB in the southwestern Paris basin, where only a few regional studies have aimed to determine their location beneath the Mesozoic sedimentary cover. Our approach is based on the reprocessing and interpretation of 36 seismic lines (1480 km) acquired by the oil industry in the 1980s in the southwestern Paris basin. We first obtain a comprehensive view of the geometry of the SPB, based on (i) the interpretation of the base of the Stephano-Permian surface (lower limit) and the erosional base of the surface of the Triassic layers (upper limit) and (ii) the recognition of specific internal geometries and seismic facies. The interpreted faults are grouped into different categories according to their period of activity, with a focus on synsedimentary faults related to thickness variations of the Stephano-Permian deposits. We then propose a structural scheme containing faults that were active during the Stephano-Permian period, in relation to the late-Variscan structural pattern which has led to the recognition of five sets of faults: N140-trending faults associated with secondary N155- and N055-trending faults (Arpheuilles basin); N115-trending faults (Contres basin); N030-trending faults (Brecy basin); NS-trending faults (transition between the Contres and Brecy basins). Based on the seismic interpretation, thickness maps are calculated both in time and in meters, allowing a pseudo-3D view of the three identified SPB, with thicknesses up to 3000 m (Contres basin); these maps indicate that the preserved extents and thicknesses of the basins in the subsurface are systematically greater than those observed at outcrop. Finally, we show that the SPB were filled during two different tectonic phases: (i) an initial period of opening of the Arpheuilles, Contres and Brecy basins, during which Stephanian conglomeratic/coal facies were deposited under a strong structural control (normal faulting with certainly a strike-slip component, wedge-shaped geometry of the sediments); (ii) a consecutive pre-Triassic tectonic activity (N155-trending strike-slip in the Arpheuilles basin, uplift of the margins of the three basins), at the origin of a significant part of the sedimentary filling of the basins; this vertical uplift may have reached 2000 m.
{"title":"Structural evolution and sedimentary record of the Stephano-Permian basins occurring beneath the Mesozoic sedimentary cover in the southwestern Paris basin (France)","authors":"L. Beccaletto, L. Capar, O. Serrano, S. Marc","doi":"10.2113/GSSGFBULL.186.6.429","DOIUrl":"https://doi.org/10.2113/GSSGFBULL.186.6.429","url":null,"abstract":"Stephanian to Permian post-orogenic basins (SPB) outcrop in several limited locations in and around the present-day French Variscan basement. Little is known about their subsurface occurrences beneath the post-depositional sedimentary cover. Our work intends to decipher the structural evolution of the hidden SPB in the southwestern Paris basin, where only a few regional studies have aimed to determine their location beneath the Mesozoic sedimentary cover. \u0000 \u0000Our approach is based on the reprocessing and interpretation of 36 seismic lines (1480 km) acquired by the oil industry in the 1980s in the southwestern Paris basin. We first obtain a comprehensive view of the geometry of the SPB, based on (i) the interpretation of the base of the Stephano-Permian surface (lower limit) and the erosional base of the surface of the Triassic layers (upper limit) and (ii) the recognition of specific internal geometries and seismic facies. The interpreted faults are grouped into different categories according to their period of activity, with a focus on synsedimentary faults related to thickness variations of the Stephano-Permian deposits. We then propose a structural scheme containing faults that were active during the Stephano-Permian period, in relation to the late-Variscan structural pattern which has led to the recognition of five sets of faults: N140-trending faults associated with secondary N155- and N055-trending faults (Arpheuilles basin); N115-trending faults (Contres basin); N030-trending faults (Brecy basin); NS-trending faults (transition between the Contres and Brecy basins). Based on the seismic interpretation, thickness maps are calculated both in time and in meters, allowing a pseudo-3D view of the three identified SPB, with thicknesses up to 3000 m (Contres basin); these maps indicate that the preserved extents and thicknesses of the basins in the subsurface are systematically greater than those observed at outcrop. \u0000 \u0000Finally, we show that the SPB were filled during two different tectonic phases: (i) an initial period of opening of the Arpheuilles, Contres and Brecy basins, during which Stephanian conglomeratic/coal facies were deposited under a strong structural control (normal faulting with certainly a strike-slip component, wedge-shaped geometry of the sediments); (ii) a consecutive pre-Triassic tectonic activity (N155-trending strike-slip in the Arpheuilles basin, uplift of the margins of the three basins), at the origin of a significant part of the sedimentary filling of the basins; this vertical uplift may have reached 2000 m.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"1 1","pages":"429-450"},"PeriodicalIF":0.0,"publicationDate":"2015-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91065623","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}
Pub Date : 2015-10-01DOI: 10.2113/GSSGFBULL.186.6.454
S. Berrada, É. Marcoux, Ahmid Hafid
Dans l’introduction de leur comment nos commentateurs (Touil A. et Hibti M.) estiment que « Les relations chronologiques et reactionnelles entre les differents stades hydrothermaux ainsi que leurs relations avec les mineralisations ne sont pas bien illustrees » dans notre article et ils proposent ce qu’ils appellent « des elements de reponse et eventuellement de nouvelles donnees permettant une meilleure comprehension des alterations hydrothermales et leurs roles dans la mise en place et la formation des mineralisations liees aux skarns d’Azegour ». Le probleme de fond de ce comment est que dans notre article nous n’avons pas aborde l’etude des mineralisations, ni du point de vue descriptif ni du point de vue genetique. Ce n’etait pas l’objectif de notre article, la mine etant aujourd’hui inaccessible, ce qui est clairement ecrit dans les premieres lignes de notre article. D’apres les commentateurs « Berrada et al. [2015] considerent que les bancs a wollastonite alternent avec les grenatites. En effet, l’allure sur le terrain laisse penser a des recurrences a wollastonite-grenatite. En revanche, l’observation detaillee sur cassure fraiche et au microscope montrent que le contact entre les grenatites du stade III et les wollastonitites du stade II est diffus et progressif » . Dans notre article nous avons effectivement utilise le terme alternance « Les wollastonitites se presentent en bancs et en lentilles sub-monominerales d’extension decametrique et de puissance variable (de 10 cm jusqu’a 2 m) alternant avec des bancs de grenatites » , mais …
中引入他们怎么我们的评论员认为(a .)先生和Hibti Touil«时序关系reactionnelles液等不同阶段之间的关系以及与mineralisations并不好illustrees»在我们的文章和他们提出他们所称的«答的内容和最终的新数据,以便更好地理解的改变而热液及其实施和维护中的角色azegour skarns矿化的形成。这篇文章的根本问题是，我们没有从描述或谱系的角度对矿化进行研究。这不是我们文章的目的，因为矿井现在是无法进入的，这在我们文章的第一行就清楚地写了出来。根据评论人士Berrada et al. [2015]， wollastonite层与石榴石交替出现。事实上，球场上的速度让人联想到沃拉斯石-石榴石的复发。另一方面，对新裂缝和显微镜的详细观察表明，III期石榴石和II期硅石之间的接触是扩散的和渐进的。在我们的文章中，我们确实使用了“交替”这个术语，“wollastonitites表现为带和亚单矿物透镜的十米延伸和可变功率(从10厘米到2米)与石榴石带交替”，但是……
{"title":"Réponse au commentaire de A. Touil et M. Hibti sur l’article “Le skarn Mo-W-Cu à grenat, wollastonite, pyroxène et vésuvianite d’Azegour (Haut-Atlas, Maroc)” de Berrada et al. (Bull. Soc. géol. France, 2015, t. 186, n°1, pp. 21– 34).","authors":"S. Berrada, É. Marcoux, Ahmid Hafid","doi":"10.2113/GSSGFBULL.186.6.454","DOIUrl":"https://doi.org/10.2113/GSSGFBULL.186.6.454","url":null,"abstract":"Dans l’introduction de leur comment nos commentateurs (Touil A. et Hibti M.) estiment que « Les relations chronologiques et reactionnelles entre les differents stades hydrothermaux ainsi que leurs relations avec les mineralisations ne sont pas bien illustrees » dans notre article et ils proposent ce qu’ils appellent « des elements de reponse et eventuellement de nouvelles donnees permettant une meilleure comprehension des alterations hydrothermales et leurs roles dans la mise en place et la formation des mineralisations liees aux skarns d’Azegour ». Le probleme de fond de ce comment est que dans notre article nous n’avons pas aborde l’etude des mineralisations, ni du point de vue descriptif ni du point de vue genetique. Ce n’etait pas l’objectif de notre article, la mine etant aujourd’hui inaccessible, ce qui est clairement ecrit dans les premieres lignes de notre article.\u0000\u0000D’apres les commentateurs « Berrada et al. [2015] considerent que les bancs a wollastonite alternent avec les grenatites. En effet, l’allure sur le terrain laisse penser a des recurrences a wollastonite-grenatite. En revanche, l’observation detaillee sur cassure fraiche et au microscope montrent que le contact entre les grenatites du stade III et les wollastonitites du stade II est diffus et progressif » . Dans notre article nous avons effectivement utilise le terme alternance « Les wollastonitites se presentent en bancs et en lentilles sub-monominerales d’extension decametrique et de puissance variable (de 10 cm jusqu’a 2 m) alternant avec des bancs de grenatites » , mais …","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"321 1","pages":"454-455"},"PeriodicalIF":0.0,"publicationDate":"2015-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79709027","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}
Pub Date : 2015-07-01DOI: 10.2113/GSSGFBULL.186.4-5.257
V. Valenti, R. Catalano, Ping-sheng Wei, Shujiang Wang
Though Sicily is a key area for understanding the central Mediterranean tectonics, a number of questions on its dynamics remains open due to the lack of detailed data on the lithospheric structure. Deep reflectivity images of the African lithosphere, beneath Sicily, have been derived from the re-processing of the crustal seismic reflection stack (SI.RI.PRO. Project). Of specific interest was the imaging, beneath central-southern Sicily, of a thinned crust with a reflective, “layered” pattern for the lower crust that differs from the one, thicker and sub-transparent, of the northern-central sector. Brittle deformation in the upper crystalline crust along a low-angle normal fault and sub-horizontal sub-Moho events are the main features, spatially associated with the “layered”, attenuated lower crust. Geological implications, which are related to the above-mentioned crustal characters, that allow us to suppose two combined hypotheses (the first suggesting that the crustal features derive from the effects of Permian and Mesozoic rifting cycles, the second connecting the crustal thinning to the latest Pliocene-Pleistocene volcanic activity and tectonics), are here discussed. The imaging of the Moho patterns and the crustal/sub-crustal reflectivity characteristics, here illustrated for the first time, could provide constraints for the geodynamic processes governing this area where an interaction between African and Tyrrhenian European plates occurs.
{"title":"Layered lower crust and mantle reflectivity as imaged by a re-processed crustal seismic profile from Sicily in the central Mediterranean","authors":"V. Valenti, R. Catalano, Ping-sheng Wei, Shujiang Wang","doi":"10.2113/GSSGFBULL.186.4-5.257","DOIUrl":"https://doi.org/10.2113/GSSGFBULL.186.4-5.257","url":null,"abstract":"Though Sicily is a key area for understanding the central Mediterranean tectonics, a number of questions on its dynamics remains open due to the lack of detailed data on the lithospheric structure.\u0000\u0000Deep reflectivity images of the African lithosphere, beneath Sicily, have been derived from the re-processing of the crustal seismic reflection stack (SI.RI.PRO. Project).\u0000\u0000Of specific interest was the imaging, beneath central-southern Sicily, of a thinned crust with a reflective, “layered” pattern for the lower crust that differs from the one, thicker and sub-transparent, of the northern-central sector. Brittle deformation in the upper crystalline crust along a low-angle normal fault and sub-horizontal sub-Moho events are the main features, spatially associated with the “layered”, attenuated lower crust.\u0000\u0000Geological implications, which are related to the above-mentioned crustal characters, that allow us to suppose two combined hypotheses (the first suggesting that the crustal features derive from the effects of Permian and Mesozoic rifting cycles, the second connecting the crustal thinning to the latest Pliocene-Pleistocene volcanic activity and tectonics), are here discussed.\u0000\u0000The imaging of the Moho patterns and the crustal/sub-crustal reflectivity characteristics, here illustrated for the first time, could provide constraints for the geodynamic processes governing this area where an interaction between African and Tyrrhenian European plates occurs.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"9 1","pages":"257-272"},"PeriodicalIF":0.0,"publicationDate":"2015-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76796902","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}
Pub Date : 2015-07-01DOI: 10.2113/GSSGFBULL.186.4-5.209
L. Thum, R. Paoli, G. Stampfli, P. Moix
The Piolit, Pelat (French Alps) and Baiardo (Italian Maritime Alps) units contain Upper Cretaceous carbonate turbidites formations, with minor siliciclastic components. They are flysch formations, linked with the Pyrenean compressive events through their ages and their “subbrianconnais” structural position. Sedimentological, mineralogical (heavy minerals), and geochemical analysis, point to a potential “Pyrenean signature” which would testify the Late Cretaceous collision between the Ibero-Brianconnais terrane and the European plate. A “Dauphinois” origin and basin inversion erosion is proposed for the zircon-tourmaline-rutile (ZTR) bearing Piolit flysch, deposited from the Coniacian to the Campanian. A Penninic origin with tectonic inversion and erosion of former tilted blocks of the European margin from the Turonian to the Paleocene is proposed for the ZTR bearing Pelat flysch. Comparison with the Niesen (Swiss Prealps) and La Ciotat (Provence) flysch depositional context, allows to better constrain the Pyrenean compressive event in the Alpine domain. The Senonian part of the Baiardo flysch, that contains a garnet-dominated heavy mineral association and distinct geochemical trends, is allotted to the Liguro-Piemontais domain and to the Alpine collision stricto sensu.
{"title":"The Piolit, Pelat and Baiardo Upper Cretaceous flysch formations (western Alps): geodynamic implications at the time of the Pyrenean tectonic phases","authors":"L. Thum, R. Paoli, G. Stampfli, P. Moix","doi":"10.2113/GSSGFBULL.186.4-5.209","DOIUrl":"https://doi.org/10.2113/GSSGFBULL.186.4-5.209","url":null,"abstract":"The Piolit, Pelat (French Alps) and Baiardo (Italian Maritime Alps) units contain Upper Cretaceous carbonate turbidites formations, with minor siliciclastic components. They are flysch formations, linked with the Pyrenean compressive events through their ages and their “subbrianconnais” structural position. Sedimentological, mineralogical (heavy minerals), and geochemical analysis, point to a potential “Pyrenean signature” which would testify the Late Cretaceous collision between the Ibero-Brianconnais terrane and the European plate. A “Dauphinois” origin and basin inversion erosion is proposed for the zircon-tourmaline-rutile (ZTR) bearing Piolit flysch, deposited from the Coniacian to the Campanian. A Penninic origin with tectonic inversion and erosion of former tilted blocks of the European margin from the Turonian to the Paleocene is proposed for the ZTR bearing Pelat flysch. Comparison with the Niesen (Swiss Prealps) and La Ciotat (Provence) flysch depositional context, allows to better constrain the Pyrenean compressive event in the Alpine domain. The Senonian part of the Baiardo flysch, that contains a garnet-dominated heavy mineral association and distinct geochemical trends, is allotted to the Liguro-Piemontais domain and to the Alpine collision stricto sensu.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"173 1","pages":"209-221"},"PeriodicalIF":0.0,"publicationDate":"2015-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86913208","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}
Pub Date : 2015-07-01DOI: 10.2113/GSSGFBULL.186.4-5.273
M. G. Morticelli, V. Valenti, R. Catalano, A. Sulli, M. Agate, G. Avellone, C. Albanese, L.uca Basilone, C. Gugliotta
Neogene-Quaternary wedge-top-basins arose during the Sicilian fold and thrust belt (FTB) build-up. The infilling sedimentary successions are: i) middle-upper Miocene silicoclastics succession, accommodated on top of the accreted Sicilide and Numidian flysch nappes; ii) upper Miocene-lower Pliocene deepening-upwards sediments unconformably overlying the inner Meso-Cenozoic deep-water, Imerese and Sicanian thrust units; iii) Upper Pliocene-Quaternary coastal-open shelf deposits unconformably covering (in the outer sector of the FTB) a tectonic stack (Gela thrust system). These successions are characterized by a basal unconformity on the deformed substrate believed to be the depositional interface common both to the coeval wedge-top and foredeep basins. The tectono-sedimentary evolution of the syn-tectonic basins was controlled by the progressive deepening of the structural levels, which were active during the growing of the FTB. The palinspastic restoration of a crustal geological transect in central Sicily points to: i) the occurrence of two subsequent, basal main thrusts (MT1 and MT2) active during the Neogene-middle Pleistocene tectonic evolution, as well as ii) a decrease in slip- and shortening-rate, estimated for the later MT2 as compared to earlier MT1 basal main thrust. The foreland-basin system evolution recorded during these two steps suggests: – the regional lithofacies distribution, during late Tortonian-early Pliocene, accounted for a wide depozone including the Iblean plateau and its offshore;– a crucial change was recorded by the late Pliocene-Pleistocene wedge-top depozone, when the deeper basal main thrust (MT2) involved and thickened (in the inner sector of the FTB) the crystalline basement (thin- to thick-skinned thrust tectonics); this change influenced the depozones, progressively narrowing up to the present-day setting. As regards this general evolutionary framework, thin-skinned and thick-skinned thrust tectonics can be recognized in the Sicilian FTB evolution. The late Tortonian-early Pliocene, thin-skinned thrust tectonics include two main tectonic events, a “shallow-seated” Event 1 and a “deep-seated” Event 2, with the Pliocene-Pleistocene thick-skinned thrust tectonics representing a third tectonic event (Event 3).
{"title":"Deep controls on foreland basin system evolution along the Sicilian fold and thrust belt","authors":"M. G. Morticelli, V. Valenti, R. Catalano, A. Sulli, M. Agate, G. Avellone, C. Albanese, L.uca Basilone, C. Gugliotta","doi":"10.2113/GSSGFBULL.186.4-5.273","DOIUrl":"https://doi.org/10.2113/GSSGFBULL.186.4-5.273","url":null,"abstract":"\u0000 Neogene-Quaternary wedge-top-basins arose during the Sicilian fold and thrust belt (FTB) build-up. The infilling sedimentary successions are: i) middle-upper Miocene silicoclastics succession, accommodated on top of the accreted Sicilide and Numidian flysch nappes; ii) upper Miocene-lower Pliocene deepening-upwards sediments unconformably overlying the inner Meso-Cenozoic deep-water, Imerese and Sicanian thrust units; iii) Upper Pliocene-Quaternary coastal-open shelf deposits unconformably covering (in the outer sector of the FTB) a tectonic stack (Gela thrust system). These successions are characterized by a basal unconformity on the deformed substrate believed to be the depositional interface common both to the coeval wedge-top and foredeep basins. The tectono-sedimentary evolution of the syn-tectonic basins was controlled by the progressive deepening of the structural levels, which were active during the growing of the FTB. The palinspastic restoration of a crustal geological transect in central Sicily points to: i) the occurrence of two subsequent, basal main thrusts (MT1 and MT2) active during the Neogene-middle Pleistocene tectonic evolution, as well as ii) a decrease in slip- and shortening-rate, estimated for the later MT2 as compared to earlier MT1 basal main thrust. The foreland-basin system evolution recorded during these two steps suggests: – the regional lithofacies distribution, during late Tortonian-early Pliocene, accounted for a wide depozone including the Iblean plateau and its offshore;– a crucial change was recorded by the late Pliocene-Pleistocene wedge-top depozone, when the deeper basal main thrust (MT2) involved and thickened (in the inner sector of the FTB) the crystalline basement (thin- to thick-skinned thrust tectonics); this change influenced the depozones, progressively narrowing up to the present-day setting.\u0000 As regards this general evolutionary framework, thin-skinned and thick-skinned thrust tectonics can be recognized in the Sicilian FTB evolution. The late Tortonian-early Pliocene, thin-skinned thrust tectonics include two main tectonic events, a “shallow-seated” Event 1 and a “deep-seated” Event 2, with the Pliocene-Pleistocene thick-skinned thrust tectonics representing a third tectonic event (Event 3).","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"186 1","pages":"273-290"},"PeriodicalIF":0.0,"publicationDate":"2015-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSSGFBULL.186.4-5.273","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68338832","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}
Pub Date : 2015-07-01DOI: 10.2113/GSSGFBULL.186.4-5.291
E. Leroux, M. Rabineau, D. Aslanian, C. Gorini, F. Bache, M. Moulin, Romain Pellen, D. Granjeon, J. Rubino
The sedimentary architecture of basins and passive margins is determined by a complex interaction of parameters, including subsidence, eustasy, and sediment supply. A quantification of the post-rift (20 Ma-0 Ma) vertical movements of the Gulf of Lion (West Mediterranean) is proposed here based on the stratigraphic study of sedimentary paleomarkers using a large 3D grid of reflection seismic data, correlations with existing drillings, and refraction data. Post-rift subsidence was measured by the direct use of sedimentary geometries analysed in 3D and validated by numerical stratigraphic modelling. Three domains of subsidence were found: on the continental shelf and slope, subsidence corresponds to a seaward tilting with different amplitudes, whereas the deep basin subsides purely vertically. We show that these domains fit with the deeper crustal domains highlighted by previous geophysical data, and that post-break-up subsidence follows the initial hinge lines of the rifting phase. Subsidence rates are quantified on each domain for each stratigraphic interval. At a constant distance from the rotational hinge line, the Plio-Quaternary subsidence rate is constant on the shelf overall. Conversely, Miocene subsidence rates are very different on the eastern and western shelves. Stratigraphic simulations focused on the Messinian salinity crisis (MSC) were also performed. Their results are discussed together with our post-rift subsidence estimates in order to provide ideas and hypotheses for future detailed quantifications of Miocene subsidence, including isostatic readjustments linked to the MSC.
{"title":"Post-rift evolution of the Gulf of Lion margin tested by stratigraphic modelling","authors":"E. Leroux, M. Rabineau, D. Aslanian, C. Gorini, F. Bache, M. Moulin, Romain Pellen, D. Granjeon, J. Rubino","doi":"10.2113/GSSGFBULL.186.4-5.291","DOIUrl":"https://doi.org/10.2113/GSSGFBULL.186.4-5.291","url":null,"abstract":"The sedimentary architecture of basins and passive margins is determined by a complex interaction of parameters, including subsidence, eustasy, and sediment supply. A quantification of the post-rift (20 Ma-0 Ma) vertical movements of the Gulf of Lion (West Mediterranean) is proposed here based on the stratigraphic study of sedimentary paleomarkers using a large 3D grid of reflection seismic data, correlations with existing drillings, and refraction data. Post-rift subsidence was measured by the direct use of sedimentary geometries analysed in 3D and validated by numerical stratigraphic modelling. Three domains of subsidence were found: on the continental shelf and slope, subsidence corresponds to a seaward tilting with different amplitudes, whereas the deep basin subsides purely vertically. We show that these domains fit with the deeper crustal domains highlighted by previous geophysical data, and that post-break-up subsidence follows the initial hinge lines of the rifting phase. Subsidence rates are quantified on each domain for each stratigraphic interval. At a constant distance from the rotational hinge line, the Plio-Quaternary subsidence rate is constant on the shelf overall. Conversely, Miocene subsidence rates are very different on the eastern and western shelves. Stratigraphic simulations focused on the Messinian salinity crisis (MSC) were also performed. Their results are discussed together with our post-rift subsidence estimates in order to provide ideas and hypotheses for future detailed quantifications of Miocene subsidence, including isostatic readjustments linked to the MSC.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"33 1","pages":"291-308"},"PeriodicalIF":0.0,"publicationDate":"2015-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79939584","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}
Pub Date : 2015-07-01DOI: 10.2113/GSSGFBULL.186.4-5.223
L. Bestani, N. Espurt, J. Lamarche, M. Floquet, J. Philip, O. Bellier, F. Hollender
The Pyrenean-Provence fold-thrust belt is characterized by a geological complexity arising from superimposed tectonic history and the propagation of the deformation through a heterogeneous mechanical substratum inherited from Paleozoic and Mesozoic times. The construction of a regional balanced cross section together with field data show that the thrust system of the southeastern Provence region is characterized by a mixed thick- and thin-skinned tectonic style related to the inversion of deep-seated late Paleozoic-Triassic extensional structures and the decollement of the Mesozoic-Cenozoic sedimentary cover above Triassic series. Earliest Cenomanian restoration state highlights the northward pinched-out of the Lower Cretaceous sedimentary series above the main long-wavelength Durance High uplift. Latest Santonian restoration state indicates a southward tilting of ~2° of the basin attributed to the initial growth of the Pyrenean-Provence prism controlling the external flexure of the foreland. Thrusts propagation in the northern part of the Pyrenean-Provence fold-thrust belt was recorded to be synchronous during latest Cretaceous to Eocene time and produced a ~7° southward basin tilting. This major tilting is attributed to the tectonic inversion and basement thrust stacking of the Cap Sicie-Sainte Baume units. Cross section balancing shows a total horizontal basement shortening of 40 km (~35 %) across the Pyrenean-Provence foreland. The main part of this shortening (~37 km) was accommodated by thick-skinned thrusts involving basement south of the Arc syncline. ~5 km of shortening were accommodated northward by the Arc syncline and eastern Sainte-Victoire thin-skin structures, resulting from slip transferred from the deep thick-skinned intercutaneous thrust wedge. Finally we interpret salt tectonic structures of the southeastern Provence as passive diapirism growth during Jurassic to late Cretaceous time, and then reactivated during Pyrenean-Provence compression. Late normal faulting related to hypothetical reactive diapirism during the Oligocene extension episode was predominantly localized above inherited salt structures and probably controlled by inherited basement faults.
{"title":"Structural style and evolution of the Pyrenean-Provence thrust belt, SE France","authors":"L. Bestani, N. Espurt, J. Lamarche, M. Floquet, J. Philip, O. Bellier, F. Hollender","doi":"10.2113/GSSGFBULL.186.4-5.223","DOIUrl":"https://doi.org/10.2113/GSSGFBULL.186.4-5.223","url":null,"abstract":"The Pyrenean-Provence fold-thrust belt is characterized by a geological complexity arising from superimposed tectonic history and the propagation of the deformation through a heterogeneous mechanical substratum inherited from Paleozoic and Mesozoic times. The construction of a regional balanced cross section together with field data show that the thrust system of the southeastern Provence region is characterized by a mixed thick- and thin-skinned tectonic style related to the inversion of deep-seated late Paleozoic-Triassic extensional structures and the decollement of the Mesozoic-Cenozoic sedimentary cover above Triassic series. Earliest Cenomanian restoration state highlights the northward pinched-out of the Lower Cretaceous sedimentary series above the main long-wavelength Durance High uplift. Latest Santonian restoration state indicates a southward tilting of ~2° of the basin attributed to the initial growth of the Pyrenean-Provence prism controlling the external flexure of the foreland. Thrusts propagation in the northern part of the Pyrenean-Provence fold-thrust belt was recorded to be synchronous during latest Cretaceous to Eocene time and produced a ~7° southward basin tilting. This major tilting is attributed to the tectonic inversion and basement thrust stacking of the Cap Sicie-Sainte Baume units. Cross section balancing shows a total horizontal basement shortening of 40 km (~35 %) across the Pyrenean-Provence foreland. The main part of this shortening (~37 km) was accommodated by thick-skinned thrusts involving basement south of the Arc syncline. ~5 km of shortening were accommodated northward by the Arc syncline and eastern Sainte-Victoire thin-skin structures, resulting from slip transferred from the deep thick-skinned intercutaneous thrust wedge. Finally we interpret salt tectonic structures of the southeastern Provence as passive diapirism growth during Jurassic to late Cretaceous time, and then reactivated during Pyrenean-Provence compression. Late normal faulting related to hypothetical reactive diapirism during the Oligocene extension episode was predominantly localized above inherited salt structures and probably controlled by inherited basement faults.","PeriodicalId":55978,"journal":{"name":"Bulletin de la Societe Geologique de France","volume":"53 1","pages":"223-241"},"PeriodicalIF":0.0,"publicationDate":"2015-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80294585","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}
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