Signatures of rapid climatic changes in organic matter records in the western Mediterranean Sea during the last glacial period

Abstract

AbstractRecords of calcium carbonate, organic matter (organic carbon content, palynology) and planktonic foraminiferal oxygen isotopes from ODP Site 976, Alboran Sea, are used to reconstruct the evolution of continental climates and oceanic productivity in the westernmost Mediterranean over the past 50,000 years. The records mimic the Greenland ice core records in that they display the Heinrich events and the rapid Dansgaard/Oeschger-type stadial-interstadial oscillations. Warm interstadials correlate with an expansion of deciduous forests on the adjacent continents and enhanced river runoff and organic matter flux from terrestrial sources. In contrast, cold stadials are characterized by an expansion of semi-desert vegetation, reduced river runoff and limited terrestrial organic matter flux. The organic carbon record displays a longer-term cyclicity that correlates with the North Atlantic ’Bond’ cooling cycles. The records enable the documentation of rapid changes of continental climates in the western Mediterranean borderlands that caused changes in river runoff and in oceanic productivity that were driven by rapid fluctuations of the Atlantic inflow into the Mediterranean Sea. The combined terrestrial-marine patterns demonstrate the close linking of western Mediterranean climate with the climatic evolution in the North Atlantic region.