Proxy development and paleoclimate of El'gygytgyn Crater Lake, NE Siberia

University Of Massachusetts Amherst, Amherst MA

Investigators

Abstract

This award will be funded by the Arctic Natural Sciences Program and the Paleoclimate Program in the Division of Atmospheric Sciences. This is a collaborative proposal by the Principal Investigator at the University of Massachusetts, with Russian colleagues in Magadan, St. Petersburg, and Vladivostok, and German colleagues at the Alfred Wegener Institute and University of Leipzeg. Lake El'gygytgyn is located within an 18 km wide meteorite impact crater that formed 3.6 million years ago in a remote part of northeastern Siberia (Chukotka) and in a region of situated between two robust atmospheric features, the Siberian High and Aleutian Low. The strength of the Aleutian Low is intimately linked to systematic changes in the tropics as reflected by analyses of variations in the robust Pacific-North American pattern (PNA). The systematics that produce the PNA pattern are believed to have robust linkages over long time scales with global circulation, allowing an evaluation of inter-hemispheric teleconnections under variable boundary conditions. In 1998, a 300,000-year sediment-core climate-record was retrieved from Lake El'gygytgyn, the oldest terrestrial Arctic record yet recovered. This record reveals reversals between oxic and anoxic lake-bottom conditions, conceivably driven by the presence or absence of permanent ice cover through summer and linked to changing regional atmospheric conditions. Therefore, it is important to understand the dynamics of the lake ice, specifically determining the environmental conditions in which it forms and melts and its effects on lake circulation. This research project will provide an understanding the post-depositional modification of the sediments and controls on a number of proxies yielding a climatic signal of hemispheric significance. Future field programs will incorporate the acquisition of new gravity cores for study of the sedimentology and mineralogy along with the biogeochemistry of the organic matter, and the isotopic geochemistry of the lake waters and sediment porewaters. These modern to recent process linkages will then be compared to the paleorecord to better quantify reliable core proxies of lake biogeochemistry at time of deposition. One of the primary goals of this project is to confirm or revise the proxy geochemistry from the lake record to consider why shifts in atmospheric circulation (as inferred from some matches with the Greenland Ice core record) persist long enough that they are recorded in a lake in Siberia. One does not expect the entire Arctic to respond in synchroneity, so it is important that records from different parts of the Arctic be compared to more fully understand how changes in one part of the Earth system impact other parts of the system.