UMR CNRS 5805 EPOC
Environnements et Paléoenvironnements
Océaniques et Continentaux

        

Consignes de Sécurité et Numéros d'Urgence
(à l'usage des personnels du laboratoire)

le 17-12-2018 à 09:30

Lieu Salle Atmosphère, Bâtiment B18N, OASU, Université de Bordeaux Intervenant(s) Christian Betzler, Univ. Hambourg

International Ocean Discovery Program (IODP) Expedition 359 cored sediments from eight borehole locations in the carbonate platform of the Maldives in the Indian Ocean. The expedition set out to unravel the Neogene Maldives platform evolution in response to changes in global climate, changes in ocean currents, and fluctuations of the sea level. The borehole results show that the stratigraphy of the carbonate sequences reliably records sea-level changes during the early and middle Miocene, with sequence boundaries forming during sea-level lowstands. Long term sea level high stands during the early Miocene and the lower to middle Miocene Climate Optimum are recorded by phases of aggradational platform growth. The middle Miocene cooling coincident with the eastern Antarctic ice sheet expansion is reflected by a progradational platform growth. This sea level control of platform growth was lost at 12.9 - 13 Ma, when the monsoon-wind driven circulation started, and the platform switched to a current-controlled mode. The example of the Maldives platform provides a detailed example of how extrinsic controlling factors on carbonate platform growth can change in time. This aspect should be taken into account when interpreting Neogene carbonate platform stratigraphy.