Impact of the South Atlantic opening on global and regional climate during Aptian and Albian times

• Main Authors: Chaboureau, Anne-Claire, Donnadieu, Y., Robin, Cécile, Guillocheau, François, Rohais, Sébastien
• Other Authors: Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS), IFP Energies nouvelles (IFPEN), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2011
• Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Austral; Brice; Sewall; South Atlantic Ocean
• Online Access: https://insu.hal.science/insu-00673869

International audience The South Atlantic ocean was initiated with a rifting phase during the Cretaceous: the Austral segment until the Walvis-Rio Grande Fracture zone opening during the upper Jurassic and lower Cretaceous, and the Central segment, from the Walvis-Rio Grande ridge to Ascension Fracture zone opening during Aptian. The latter is characterized by the presence of a thick salt layer (Brice et al., 1982; Brognon et Verrier, 1996), distinctive of an arid climate. During the connexion between the North and the South Atlantic during Albian times, a wet climatic belt occurs north of the Central segment (Chumakov et al., 1995). What does the occurring of this belt mean? What is the impact of the South Atlantic opening on climatic changes? What are the consequences on the sedimentary deposits? In order to integrate climatic controls in sedimentary record of this section of the South Atlantic, we used an Earth system model called FOAM (for Fast Ocean Atmopshere Model) allowing to integrate and to simulate the consequences of the South Atlantic ocean opening. Three continental configurations were used: Lower and Upper Aptian, and Albian, according to palaeogeography of Sewall et al., 2007. Elevation of Andes and paleoshorelines were modified for the american and african cratons. Owing to the existing uncertainties about the elevation of the rift, we tested 1000m and 3000m of rift shoulders. The atmospheric CO2 concentration was kept constant for the three experiments, and set at 1120ppm. On a global scale, contrary to the evolution of the climatic zonation suggested by Chumakov et al., 1995, we found that the wet climatic belt north of the Central segment is a robust and constant feature of our simulations for the entire studied time period (125-109 Ma). The situation of this belt (ITCZ for Intertropical Convergent Zone) is not disrupted by a rift shoulder of 1000m. Conversely, the presence of a rift shoulder of 3000m plays a major role, the ITCZ becomes discontinuous on the African continent, and a monsoon ...