OS2.6Climatic causes and consequences of Mediterranean-Atlantic gateway exchange from Miocene to present
|Convener: Rachel Flecker|
Today, Mediterranean-Atlantic exchange is a key control on Mediterranean environmental conditions. It also enhances Atlantic Meridional Overturning Circulation (AMOC) and hence influences both northern hemisphere and global climate. The geometry of the Atlantic-Mediterranean linkage has changed considerably over the last ten million years. In the Late Miocene two marine gateways, the Betic corridor southern Spain and the Riffian connection in northern Morocco, gradually closed as a consequence of tectonic convergence between Africa and Eurasia. This restricted Mediterranean-Atlantic exchange and resulted in massive salinity fluctuations in the Mediterranean, an event known as the Messinian Salinity Crisis. Normal marine conditions began to be re-established in the Mediterranean around 5.3 Ma when a new Mediterranean-Atlantic gateway at Gibraltar opened up. Warm, saline Mediterranean Outflow Water (MOW) started to circulate in the North Atlantic Ocean, shaping the seafloor through along-slope oceanographic processes and thereby profoundly influencing the deep-sea sedimentary record. Late Miocene to Quaternary changes reflect the complex interplay between tectonic activity, climate, sea-level and sedimentation. In addition, orbital variability has also been a profound driver of the volume and physical properties of MOW throughout its history.
Because of the high amplitude environmental response of the Mediterranean to subtle climate shifts, records of its exchange with the Atlantic are numerous and diverse. The potential palaeoceanographic information derived from sediment records near these gateways (as contourite drifts) and from onshore successions preserved within the fossil corridors, is essential for resolving the history of environmental change in this region and its role in oceanic circulation and modulating Earth’s climate. This session aims to bring together scientists from a wide range of disciplines working on all aspects of Mediterranean-Atlantic exchange from Miocene to present day. It particularly seeks to showcase new research on marine records and/or adjacent on-shore successions from the following areas: a) Betic and Riffian corridors; b) the Alboran Sea; c) the Gulf of Cadiz and off-shore Portugal (including recent results of IODP drilling); and d) the Moroccan margin.