A tephra lattice for Greenland and a reconstruction of volcanic events spanning 25–45 ka b2k. (15th June 2015) - Bourne, A.J.
Abstract: Tephra layers preserved within the Greenland ice-cores are crucial for the independent synchronisation of these high-resolution records to other palaeoclimatic archives. Here we present a new and detailed tephrochronological framework for the time period 25, 000–45, 000 a b2k that brings together results from 4 deep Greenland ice-cores. In total, 99 tephra deposits, the majority of which are preserved as cryptotephra, are described from the NGRIP, NEEM, GRIP and DYE-3 records. The major element signatures of single glass shards within these deposits indicate that 93 are basaltic in composition all originating from Iceland. Specifically, 43 originate from Grimsvötn, 20 are thought to be sourced from the Katla volcanic system and 17 show affinity to the Kverkfjöll system. Robust geochemical characterisations, independent ages derived from the GICC05 ice-core chronology, and the stratigraphic positions of these deposits relative to the Dansgaard-Oeschger climate events represent a key framework that provides new information on the frequency and nature of volcanic events in the North Atlantic region between GS-3 and GI-12. Of particular importance are 19 tephra deposits that lie on the rapid climatic transitions that punctuate the last glacial period. This framework of well-constrained, time-synchronous tie-lines represents an important step towards the independent synchronisation of marine, terrestrial and ice-core records from the North Atlantic region, in order to assess the phasing of rapid climatic changes during the last glacial period. Highlights: 99 tephra deposits comprise the 25–45 ka b2k Greenland Tephra Framework. Grimsvötn, Katla and Kverkfjöll the most productive volcanic systems. 14 tephras can be correlated between at least 2 ice-cores. 19 tephras lie at the rapid climatic transitions that punctuate the Last Glacial.