Divulgação

Palestra - "The Arctic Ocean in the Cenozoic climate system”.

Data: 2013-10-28 11:00 AM
Orador/Formador: Claude Hillaire-Marcel
Local: IPMA Algês Lisboa
Contacto email:
Contacto telefónico: 214770000

The history of the Arctic Ocean remained poorly known until the 2004 IODP coring of Lomonosov Ridge sediments which revealed the existence of an Eocene ‘lake-stage’ prior to the marine submergence (e.g., Moran et al., Nature 441, 2004). As a consequence of high latitude plate tectonics movements, the opening of Fram Strait (cf. Jakobsson et al., Nature 447, 2007) allowed input of North Atlantic marine water into the Arctic basin leading to a shift from lacustrine to marine environmental conditions.Osmium isotope stratigraphy and Re-Os isochrons concur to assign a Late Eocene age (~36 Ma) to this lake drainage/marine submergence event (Poirier & Hillaire-Marcel, GRL 36, 2009; GRL 28, 2011). This late Eocene opening of Fram Strait confers a potential role to the Arctic basin into the inception of the Atlantic Meridional Overturning Circulation (AMOC) during the Early Oligocene (Davies et al., Nature 410, 2001). Coring expeditions of the last decade yielded complementary records spanning the last few climatic cycles, although stratigraphies, in the central Arctic Ocean notably, remain open to debate beyond a few tens of thousand years. Nonetheless, the late deglaciation is sufficiently well documented to illustrate the potential role of export of Arctic Ocean sea-ice and freshwater into instabilities of the AMOC.