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Impact du climat et de la tectonique sur la dynamique des systèmes sédimentaires pendant l'ouverture de l'Atlantique Sud

Abstract : The opening of the South Atlantic was initiated by a rifting phase during the Early Cretaceous. During this period a large salt sequence develops in the Central segment. The presence of evaporites, commonly associated to an arid climate, suggests the possibility of having, during the Cretaceous, arid zones close to the equator. This observation raises majors questions: what was the incidence of the rifting on the climate ? And what were the roles of these two processes on the sedimentary dynamic and particularly during the salt deposit? In this purpose a numerical modeling approach was chosen and three major steps were followed: (1) paleogeographic synthesis, (2) climate modeling, and (3) stratigraphic modeling. The paleogeographic synthesis has highlighted, in a first time, a diachronous evolution of rift activity, early in the northern part of the Central segment before spreading in the southern part, and secondly to clarify the chronology of two phases of extension, rift and sag. Climate models have shown the existence of a humid climatic belt northern to the study area, and a strong seasonality. Finally, stratigraphic modeling revealed the importance of taking into account (1) of this seasonality pattern and (2) of the paleogeography of the Central segment. The interaction between the three thematic has clarified the importance of the control factors for the formation of evaporites. Thus, (1) the climate played a major role in providing favorable climatic conditions due to the seasonnality, but (2) the rift has been the primary control factor by allowing a subsidence for marine connection and income of salt for deposition of evaporites in a restricted basin.
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Submitted on : Wednesday, June 5, 2013 - 10:45:03 AM
Last modification on : Thursday, June 2, 2022 - 2:48:11 PM
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  • HAL Id : tel-00830475, version 1

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Anne-Claire Chaboureau. Impact du climat et de la tectonique sur la dynamique des systèmes sédimentaires pendant l'ouverture de l'Atlantique Sud. Stratigraphie. Université Rennes 1, 2012. Français. ⟨NNT : ⟩. ⟨tel-00830475⟩

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