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Volcanic activity in the Eifel (central Europe) occurred systematically in the millennium before the abrupt North Atlantic warming events of the last 130.000 years - endogenic or exogenic forcing processes?

Frank Sirocko , Frederik Krebsbach

Abstract

The analysis of tephra layers in maar lake sediments of the Eifel shows 14 well-visible tephra layers during the last glacial cycle (0--130,000 BP). These tephra were analyzed for their geochemical and petrographic composition, which allows us to connect several tephra to eruption sites. All tephra were dated by application of the ELSA-23 lake sediment chronology, which covers the entire last glacial cycle in the maar records from Hoher List, Auel, and Holzmaar. Apparently, all 14 tephra were close to interstadial warming events in the Greenland ice and North Atlantic sea surface temperatures. In particular, phreatomagmatic maar eruptions were systematically associated with Heinrich or C-events. The two millennia before the northern warming events represent times of warming of the Southern Hemisphere, global sea level rise and CO2 increase. The synchroneity within only two millennnia documents a most likely physical relationship between endogenic and exogenic geodynamic processes with climate. Changes in the lithospheric stress field in response to changes in continental ice loads is one potential candidate to explain the connection. Alternatively, a primary forcing from endogenic processes in the upper mantle (heat flow or eruptions under the ice) could be responsible for ice sheet instability. Which of the two processes is indeed the primary forcing cannot be evaluated with confidence. The chronology of volcanic activity in the Eifel in comparison to the chronology of global climate change and northern hemisphere ice sheet decay demonstrates however that intraplate mantle plumes appear to be connected with continental ice sheets and sea level.