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6 results on '"R. Couëffé"'

1. The Central English Channel troughs: major source-to-sink remnants or giant tidal scours?

Author

F. Paquet, I. Thinon, O. Dugué, B. Tessier, M. Benabdellouahed, E. Lasseur, J. Briais, R. Couëffé, P. Guennoc, V. Gaullier, Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Morphodynamique Continentale et Côtière (M2C), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord]), and BRGM - RGF Plateau Continental

Subjects
Geophysics, [SDU]Sciences of the Universe [physics], Stratigraphy, Tidal scours, Central English Channel, Economic Geology, Geology, Neogene, Oceanography, Paleovalleys, Troughs
Abstract

International audience; The Central English Channel troughs correspond to elongated incisions up to 250 m-deep, at several locations at the bottom of this sea corridor. Depending on their location, they are usually interpreted as part of the submerged quaternary paleovalley network or as resulting from megaflood events. Shedding light on these features, their age, and the processes underlying their development is key for understanding their significance in terms of event geology. The interpretation of a dense grid of high-resolution marine seismic data acquired in the Bay of Seine area reveals that the extensive Quaternary paleovalley and trough network commonly as associated to the "Channel River" system is actually subdivided into at least two superimposed and unrelated incised networks. The overlying network corresponds to fluvial incisions developing during low sea-level conditions of Pleistocene time and connects to the present day fluvial network. The underlying network corresponds to the troughs and appears as a complex, deeper, relatively discontinuous and isolated network. This older network shows unexpected local incision depth up to c.350-400 m-deep and complex sedimentary infill involving several sedimentary processes and environments from fluvial to tidal and shallow-marine. We discuss these observations and their implications for understanding the origin, age and development of the troughs all over the English Channel, from the Dangeard Troughs in the Dover Strait to the Hurd Deep at the western end. We also raise questions about the significance of these large incised features in terms of source-to-sink system of northwestern Europe.

Published
2023

2. Theoretical models of fracture deformation based on aperture distribution.

Author

Ma, Haichun, Feng, Peichao, Qian, Jiazhong, Tan, Xiaohui, Wang, Jingping, Ma, Lei, and Luo, Qiankun

Abstract

The theory of rock fracture deformation is mainly based on the test, and the empirical formula has the parameters differences and inadequate theoretical logicality. Based on the processes of the fracture closure under normal stress and the fracture aperture distribution models including the power function form and normal function, the applied force causes the increase of the fracture contact area and the deformation modulus. Thus, we obtain the theoretical expression of force versus the deformation. We also propose a method that can predict the closure of the rock fracture contact area. The incremental area of fracture closure generated under each normal stress can be considered as the aperture increase effect corresponding to each displacement change amount to obtain the aperture distribution frequency corresponding to each stage load. The curves calculated by the theoretical models can fit well with the existing theoretical and experimental results, indicating that the proposed fracture deformation theory is reasonable. This paper expounds the fracture deformation theory, which has an important theoretical value for the rock mass engineering stability and the fracture seepage theory. [ABSTRACT FROM AUTHOR]

Published
2022
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3. Middle Stone Age Bifacial Technology and Pressure Flaking at the MIS 3 Site of Toumboura III, Eastern Senegal.

Author

Schmid, Viola C., Douze, Katja, Tribolo, Chantal, Martinez, Maria Lorenzo, Rasse, Michel, Lespez, Laurent, Lebrun, Brice, Hérisson, David, Ndiaye, Matar, and Huysecom, Eric

Subjects
MESOLITHIC Period, OPTICALLY stimulated luminescence, PLEISTOCENE Epoch
Abstract

Copyright of African Archaeological Review is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2022
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4. The Geology of North Africa

Author

Zakaria Hamimi, Moulley Charaf Chabou, Ezzoura Errami, Abdel-Rahman Fowler, Nuri Fello, Amara Masrouhi, Rémi Leprêtre, Zakaria Hamimi, Moulley Charaf Chabou, Ezzoura Errami, Abdel-Rahman Fowler, Nuri Fello, Amara Masrouhi, and Rémi Leprêtre

Subjects
Geology, Geophysics, Mineralogy, Petrology
Abstract

This richly illustrated book reviews the geology, tectonics, sedimentary basins and strategic resources of North Africa in 21 chapters. Chapter 1 is a regional synthesis. Chapter 2 examines the deep crustal and upper mantle structure. Chapter 3 compares the West African Craton. Chapters 4,5,6,7 deal with Pan-African-, Variscan (Hercynian)- and Alpine-Belts. Precambrian Geology of Hoggar Shield, north Central Africa will be addressed in Chapter 8. The North African Neoproterozoic and Phanerozoic sedimentary basins are the topic of Chapter 9. Phanerozoic magmatism and geodynamic framework of North Africa are addressed in Chapter 10. Chapters 11,12 deal with petroleum geology and water resources. Important non-metallic- and metallic- ore deposits are presented in Chapter 13,14,15,16. Chapters 17,18 explore geothermal energy and other strategic resources. Chapters 19,20 discuss seismicity, seismotectonics and Neotectonics, and Advances of exploration geophysics in North Africa. The lasttwo chapters (20, 21) focus on meteoric impact craters, geoheritage, geoparks and geotourism in North Africa.

Published
2024

5. L'exploration géologique de la Provence : Deux siècles et demi de débats et de controverses

Author

Jean Philip and Jean Philip

Subjects
Geology--History.--France--Provence
Abstract

Des premières observations naturalistes de la seconde moitié du XVIIIe siècle émerge une première vision d'ensemble de la Provence, divisée en trois régions : marneuse, calcaire et schisteuse. L'étape suivante, qui débute dans les années 1820, est dominée par la nécessité de définir le cadre stratigraphique et marquée par la publication des premières descriptions géologiques régionales. À partir de 1884, sous l'impulsion de Marcel Bertrand et de ses disciples, la Provence se trouve placée au centre des préoccupations de nombreux géologues, suite à la découverte des grands chevauchements de la couverture sédimentaire et du socle cristallin. Ainsi s'ouvre une période faste qui se poursuivra pendant le premier quart du XXe siècle. Toutefois, à partir des années 1930, les conceptions de Marcel Bertrand sont remises en question par les géologues autochtonistes. Puis, au cours des années 1960, celles-ci sont à leur tour réfutées par de nouveaux travaux qui conduisent à une réhabilitation éclatante de l'oeuvre du célèbre tectonicien. Au cours des décennies suivantes, l'exploration géologique et géophysique se développe et s'étend au précontinent. Stimulées par l'établissement de la carte géologique à 1/50 000, les recherches vont accorder une place importante à l'étude des grands problèmes stratigraphiques, paléogéographiques et structuraux, conduisant ainsi, au tout début du XXIe siècle, à l'établissement de synthèses géodynamiques de la Provence dans le cadre de la tectonique globale. L'ouvrage relate les différents épisodes de cette exploration ainsi que les débats et les controverses qui l'ont accompagnée. Illustré de nombreuses coupes et cartes originales il renferme plus de 500 références bibliographiques, ainsi que les biographies des principaux acteurs de cette longue et passionnante aventure scientifique.

Published
2015

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