88 Were Abrupt Climatic Changes at the Last Termination Globally Synchronous (Posters)

Wednesday, 30 July 2003
1:30 PM - 4:30 PM

DETAILED CORRELATION OF RECORDS IN THE NORTH-ATLANTIC REGION DURING THE LAST GLACIAL-INTERGLACIAL TRANSITION

Paper number: 88-10
Program: SYMPOSIA
Time: 1:30 PM – 4:30 PM

Authors

Abstract

Correlation of records covering the Last Glacial-Interglacial Transition can be established in different ways. Based on a combination of different lines of evidence the high resolution terrestrial records from the North Atlantic Seaboard can be correlated in detail, not only to each other, but also to the Greenland Ice-cores. Based on this correlation, it can be concluded that events recorded in the ice-core and terrestrial archives appear to be more or less synchronous, which implies an intimate link between both environments through atmospheric, climate, coupling. On the other hand, the climate system is influenced by ocean processes. The influence of the Atlantic on the terrestrial climate can be exemplified by analysing the spatial effects of this strong climate signal during the Younger Dryas (GS-1) in NW Europe. Marine records from the North Atlantic indicate important changes in sea-ice distribution and associated circulation patterns during the LGIT.

In order to test current ideas about ‘leads’ and ‘lags’ in the North Atlantic climate system a detailed correlation between records from the different environments is imperative. The majority of records for the LGIT obtained from marine and terrestrial sequences have been dated using 14C and can be correlated chronostratigraphically. However, fossils obtained from marine sequences are subject to an ‘apparent age’, or marine reservoir effect, caused by a.o. the slow mixing of ocean waters and the upwelling of C-14 depleted waters. Furthermore, it is now clear that the marine reservoir effect has not remained constant throughout the LGIT, neither in time, nor space. At present, this remains one of the major limitations on the correlation of marine and terrestrial records, for the uncertainties associated with age estimates based on marine fossils can be well in excess of the analytical precision of the 14C dates themselves.

Time-parallel events in the geological record, which provide important ‘tie-lines’ between marine, terrestrial and ice-core sequences, offer an alternative basis for the dating and correlation of events during the LGIT. Furthermore, the event-stratigraphy approach can be used to get a better grip on the marine reservoir ages, and thus can help to improve the value of existing C-14 chronologies and future land-ocean correlation.