FIRST COLLABORATIVE RESULTS FROM LAKE EL'GYGYTGYN CRATER: PROXIES OF CHANGE SINCE 3.6 MA, NE RUSSIAN ARCTIC

Lake El’gygytgyn in NE Russia is a meteorite crater formed 3.6 Myr ago in northeast Russia, 100 km north of the Arctic Circle (67°30’ N, 172°05’ E). Drilling in spring 2009 recovered a sediment record reaching 315 m below lake floor capturing changes in limnological properties recording elements of climate change across the western Arctic. The geochronology, so far, is based on paleomagnetic properties measured from U-channels and core catcher samples tuned to precession but anchored by more than 10 tephra units, OSL, and pollen stratigraphy. More than 50 international scientists – faculty and graduate students are jointly involved in the labor intensive, analytical aspects of core processing.

The lowest 15 meters of the sediment record appear to be barren based on core catcher samples so far analyzed. This may be due to the intense heat of the post-impact environments. Preliminary pollen analysis of the Pliocene section indicates that environmental conditions were not uniformly warm but that cool and warm cycles were characterized by the presence of tree pollen, providing a compositional idea of Pliocene El’gygytgyn forests of alder (Alnus), hemlock (Tsuga), fir (Abies), spruce (Picea) and tree pine (Pinus), not just shrubs. Larch pollen is a common element in the record. ITRAX scanning, color spectra, FTIRS, and diatom analyses demonstrate that past interglacials were not uniform in intensity at this high latitude site. Rather, isotope stages 9 and 11 are remarkable in intensity, stronger than other proxies for stages 5e. Core processing and lithological characterization is ongoing but our initial results confirm the continuous nature of the paleoclimate record and the representative nature of this site for understanding change across the western Arctic. Whether Arctic climate changed in steps, jolts or plunges at glacial/interglacial transitions and the onset of Northern hemisphere glaciation will only come from study of the continuous record over the coming year.