You are here:
Noble Gas Proxy Evidence Of Holocene Climate Fluctuations In The Elwha Watershed, Olympic Mountains, Washington
Citation:
SIDLE, W. C. AND V. Cvetic. Noble Gas Proxy Evidence Of Holocene Climate Fluctuations In The Elwha Watershed, Olympic Mountains, Washington. Presented at Annual Quaternary Research Meeting, University of Washington, Seattle, WA, December 08 - 10, 2008.
Impact/Purpose:
To share information
Description:
Paleotempertures retrieved from the groundwater archives in the largest watershed (≈800 km2) in the Olympic Mountains suggest asynchronous Olympic Peninsula climate responses during the Everson interstade period after the last continental glacial maximum. Dissolved noble gases from 63 springs and seeps were analyzed by HR-noble gas laser mass spectroscopy. Solubility equilibriums in 41 samples are preserved from the time of recharge to the local water tables or the piezometric surface for the aquifers. Noble gas temperatures (NGT) during recharge in the Elwha watershed range from 3.9 °C to 12.4 °C. These mean surface air temperatures have an error of 0.6 °C according to a non-linear inverse code NOBLEISO which was written for closed system equilibration modeling. Present surface air temperatures averaged 10.4°C during the last 15 years from the recharge season (June – September) within the Olympic Mountains. Timelines of recharge events were estimated by 14CDIC, 39Ar, 85Kr, 3H, and 3H-3He age dating. The ages of sampled groundwater range from 10 yr BP to 8510 yr BP. These proxy NGT measurements of recharge temperatures along with recharge ages are the first quantitative measurements of the past climate for the Olympic Peninsula. They suggest that during the Holocene, the climate was much warmer from 3000-2000 yr ago, cooler from 1000-100 yr ago, and much cooler from 9000-7000 yr ago when compared to present air temperatures on the Peninsula.