A 110,000-YR RECORD OF EXPLOSIVE VOLCANISM FROM THE GISP2 (GREENLAND)ICE CORE

The time series of volcanically produced sulfate from the GISP2 ice co re is used to develop a continuous record of explosive volcanism over the past 110,000 yr. We identified similar to 850 volcanic signals (70 0 of these from 110,000 to 9000 yr ago) with sulfate concentrations gr eater than that associated with historical eruptions from either equat orial or mid-latitude regions that are known to have perturbed global or Northern Hemisphere climate, respectively. This number is a minimum because decreasing sampling resolution with depth, source volcano loc ation, variable circulation patterns at the time of the eruption, and post-depositional modification of the signal can result in an incomple te record. The largest and most abundant volcanic signals over the pas t 110,000 yr, even after accounting for lower sampling resolution in t he earlier part of the record, occur between 17,000 and 6000 yr ago, d uring and following the last deglaciation. A second period of enhanced volcanism occurs 35,000-22,000 yr ago, leading up to and during the l ast glacial maximum. These findings further support a possible climate -forcing component in volcanism. Increased volcanism often occurs duri ng stadial/interstadial transitions within the last glaciation, but th is is not consistent over the entire cycle. Ages for some of the large st known eruptions 100,000-9000 yr ago closely correspond to individua l sulfate peaks or groups of peaks in our record. (C) 1996 University of Washington.