T17 Lakes and Holocene Environmental Change: The Use of Multiproxy Lake Records for Paleoclimate Reconstructions I

Sunday, 2 November 2003
8:00 AM - 12:00 PM

AN 8,000 YEAR RECORD OF METEORIC d18O IN THE NORTHWEST SUB-ARCTIC FROM JELLYBEAN LAKE, YUKON TERRITORY, CANADA

Paper number: T17-7
Program: Technical Sessions
Time: 9:30 AM – 9:45 AM

Authors

Abstract

An increasing number of hypotheses for Northern Hemisphere climatic teleconnections emphasize the need for well dated, high quality resolution records of meteoric d18O from the northwest Pacific. With the exception of the proxy data for meteoric oxygen isotope composition for the last 300 years from the Mount Logan ice core retrieved in 1980 (Holdsworth et al, 1992) there is no other data in the northwest Pacific sub-arctic region. New ice cores recently retrieved from the summit of Mt. Logan that span the entire Holocene are essential towards this goal. However the lingering question of how closely related the oxygen isotope composition of snow at high elevations is to lower elevation precipitation remain unresolved by high elevation ice core records alone. Here we present a record of low elevation meteoric d18O from Jellybean Lake located in the southern Yukon Territory (60.35145 oN, 134.80536 oW, 730 m elevation) approximately 300 km southeast of the Mt. Logan massif.

Jellybean Lake’s hydrologic and sedimentary processes in addition to the isotopic relationship between the lake-water, local spring and meteoric water make a strong argument that the sedimentary carbonate d18O is a proxy for meteoric waterd18O. Cores that were analyzed for sedimentary and isotopic properties also include seven radiocarbon ages, Lead-210 on the uppermost sediments and the White River Ash to constrain the chronology. The sedimentary d18O vary between –18 and –21 ‰ VPDB and do not indicate any pervasive cycle or low frequency trend. Notably abrupt step-wise shifts distinguish the record from Greenland and other high arctic ice cores. It is hopeful that the Jellybean record will provide valuable insight into the controls of the northwest region’s meteoric isotopic composition and thus clarify appropriate climatic connections with other regions during the Holocene.