A Paleomagnetic Assignment of Neogene Stage Boundaries and the Development of Isochronous Datum Planes between the Mediterranean, the Pacific and Indian Oceans in Order to Investigate the Response of the World Ocean to the Mediterranean 'Salinity Crisis'.

摘要

Biostratigraphic correlations allow the paleomagnetic reversal sequence measured on sedimentary sections from selected type-areas of the European Neogene stages to be recognized in terms of both the magnetic epoch nomenclature established on Equatorial-Pacific piston cores and the magnetic anomaly patterns mapped across the axial region of the mid-oceanic ridge. The lower boundaries of the following stages are identified and tentatively dated according to the latest revised paleomagnetic time scales of Talwani et al. (1971) and Blakely (1974). The biostratigraphic correlations show that the isolation of the Mediterranean Sea from the open ocean during the Messinian stage of the Upper Miocene was accompanied by a major high latitude cooling, a glacial-eustatic sea-level lowering, and a large upward excursion of the Calcium Compensation Depth and associated lysocline recognizable in the Pacific, Atlantic and Caribbean. These events are believed to have been initiated by the subtraction of more than 6% of the dissolved salts of the World Ocean during the Mediterranean 'salinity-crisis' when one million cubic kilometers of evaporites were deposited on the floor of the Mediterranean Sea in less than 1,100,000 years.