Autre(s) version(s) : 2006-2007 2004
Glaciation ; Crises biologiques
Au cours des temps phanérozoïques, les interactions entre changement global et biodiversité sont particulièrement visibles lors des phases de crises, et en particulier lors des grandes glaciations. A partir du décryptage des archives sédimentaires de la plate-forme nord-gondwanienne, nous proposons dans ce projet d’examiner la fin de la période ordovicienne (Paléozoïque inférieur) en termes de dynamique de l’environnement de dépôt glaciaire, d’évolution des communautés fauniques, et de modélisation paléoclimatique. L’étude de cet intervalle de temps permet de travailler sur un système relativement simple, associant une crise biologique majeure et une glaciation, dans lequel le forçage climatique est prépondérant. L’analyse de l’impact d’une glaciation sur la biosphère nécessite de confronter le calendrier des événements glaciaires avec celui des différentes phases ponctuant l’évolution de la biodiversité (crises\/colonisations). Notre projet s’articule ainsi autour de trois interrogations fondamentales : (1) Quels étaient l’ampleur et le calendrier des événements glaciaires fini-ordoviciens? (2) Quelles sont les relations entre la glaciation fini-ordovicienne et la dynamique de changement de la biodiversité? (3) La glaciation fini-ordovicienne représente-t-elle une catastrophe climatique ou la manifestation extrême d’un épisode de type icehouse?
Glaciation ; Crises biologiques
Relationships between global change and biodiversity in the Phanerozoic are well expressed during crises, particularly if those are penecontemporaneous with glaciations. Based on the analysis of the north-Gondwana sedimentary record, the aim of this project is to examine the Late Ordovician period (Lower Palaeozoic) especially as concern depositional environments, dynamics of biological communities and palaeoclimatic modeling. This time range allows to study a system with minimal complications, characterized by the association of a major biological crisis with a continental-wide glaciation, within which forcing is predominantly related to climate change. The analysis of the effects of a glaciation onto the biosphere implies to compare the timing of glacial events to the timing of biodiversity changes. Consequently, our project is structured in three part corresponding to the following questions: (1) What were the extent and timing of the Late Ordovician glacial events? (2) What were the relationships between the glaciation and the biodiversity changes? (3) Was the latest Ordovician glaciation a climatic catastrophe, or was it the glacial maximum of an icehouse period?
GHIENNE
Jean-François
Université Louis Pasteur Strasbourg 1 - Centre de Géochimie de la Surface (CGS)
UMR 7517
Ghienne J.F., Deynoux M., Manatschal G., Rubino J.-L. (2003). Palaeovalleys and fault-controlled depocenters in the Late Ordovician glacial record of the Murzuq Basin (Central Libya). Comptes Rendus Geoscience 335, 1091-1100 .
Servais T., Li J., Molyneux S.G., Raevskaya E. (2003). Ordovician organic-walled microphytoplankton (acritarch) distribution : the global scenario. Palaeogeography, Palaeoclimatology, Palaeoecology Special Issue, 195 (1-2), 149-172 .
Servais T., Alvaro J.J., Blieck A. (2003). Early Palaeozoic Palaeo(bio)geographies of Western Europe and North Africa. Palaeogeography, Palaeoclimatology, Palaeoecology Special Issue, 195 (1-2), \\N .
Ghienne J.-F. (2003). Late Ordovician sedimentary environments, glacial cycles, and post-glacial transgression in the Taoudeni Basin, West Africa. Palaeogeography, Palaeoclimatology, Palaeoecology 189, 117-145 .
Blieck A., Turner S. (2003). Global Ordovician vertebrate biogeography. Palaeogeography, Palaeoclimatology, Palaeoecology Special Issue, 195, 37-54 .
Monod O., Kozlu H., Ghienne J-F., Dean W.T., Günay Y., Le Hérissé A., Paris F., Robardet M. (2003). Late Ordovician glaciation in Southern Turkey. Terra Nova 15, 249-257 .
Konaté M., Guiraud M., Lang J. (2003). Sedimentation in the Kandi extensional Basin (Benin and Niger): fluvial and marine deposits related to the Late Ordovician deglaciation in West Africa. Journal of African Earth Sciences 36, 185-206 .
Botquelen A., Loi A., Gourvennec R., Leone F., Dabard M.P. (2004). Formation et signification paléo-environnementale des concentrations coquillières : exemples de l'Ordovicien de Sardaigne et du Dévonien du Massif armoricain. Comptes Rendus Palevol 3, 353-360 .
Vecoli, M., Le Hérissé A. (2004). Biostratigraphy, taxonomic diversity and patterns of morphological evolution of Ordovician acritarchs (organic-walled microphytoplankton) from the northern Gondwana margin in relation to palaeoclimatic and palaeogeographic changes. Earth Science Review 67, 267-311 .
Deynoux M., Ghienne J.F. (2004). Late Ordovician glacial pavements revisited - a reappraisal of the origin of striated surfaces. Terra Nova 16, 95-101 .
Webby, B.D., Paris, F., Droser, M., Percival I. (2004). The Great Ordovician Diversification Event. Columbia University Press, New York \\N, 484 p. .
Li J., Servais T., Yan Y., Zhu H. (2004). A nearshore-offshore trend in the acritarch distribution of the EarlyMiddle Ordovician of the Yangtze Platform, S-China. Review of Palaeobotany and Palynology 130, 141-161 .
Bouhrahrouh A., Paris F., Elaouad-Debbaj Z. (2004). Biostratigraphy, biodiversity and palaeoenvironments of the chitinozoans and associated palynomorphs from the Upper Ordovcian of the Anti-Atlas, Morocco. Review of Palaeobotany and Palynology 130, 17-40 .
Lefebvre B., Ghobadipour M., Nardin E. (2005). Ordovician echinoderms from the Tabas and Damghan regions, Iran : palaeobiogeographical implications. Bulletin de la Société Géologique de France 176, 231-242 .
Moreau J., Ghienne J.-F., Le Heron D., Rubino J.-L., Deynoux M. (2005). 440 Ma old ice stream in North Africa. Geology 33, 753-756 .
Denis M., Buoncristiani JF., Konate M., Yahaya M., Guiraud M. (2006). Typology of Hirnantian glacial pavements in SW Djado Basin (NE Niger). Africa Geoscience Review 13, 1-2, 145-157 .