Rock Magnetic Properties of Lake El'gygytgyn: Implications for Paleoclimatic Reconstruction
Abstract
Lake El'gygytgyn is a meteor impact lake formed ~3.6 Ma in Northeast Siberia (67°30'N 172°05'E). The lake is believed to have escaped Plio-Pleistocene glaciation, and therefore should provide an uninterrupted sedimentary record from mid-Pliocene to present. Recently an international team of geoscientists completed a drilling expedition at the lake, recovering over 300 meters of sediment that is providing extensive information for paleoclimate reconstructions of the High Arctic. Current work indicates the long cores contain a high resolution terrestrial record of continuous deposition back to 3.5Ma. Basic magnetic properties (magnetic susceptibility and paleomagnetic directions) were measured at GFZ Potsdam (Haltia-Hovi & Nowaczyk) and are being utilized to create a detailed magnetochronostratigraphy for Lake El'gygytgyn. This study focused on the rock magnetic properties of the sediment during Marine Isotope Stage 31, approximately 1.07Ma. Initial measurements of this time period suggest a period of extreme warmth, which may be applicable to future climate models. Previous rock magnetic studies using MPMS low temperature measurements and hysteresis measurements on short cores from Lake E reveal the presence of the carbonate mineral siderite (and possibly rhodochrosite) as well as vivianite. The presence of these minerals force us to reconsider environmental conditions at the time of formation. Similar rock magnetic measurements of Stage 31 will aid in identifying magnetic minerals, the presence of which will help us to better understand lake conditions a million years ago. Utilizing rock magnetic properties to distinguish which magnetic minerals are present, even in minute amounts, is an important and effective method that can be combined with other geologic disciplines (inorganic geochemistry, biogeochemistry, sedimentology, etc.) to more accurately understand lake conditions, sedimentary environments, and post-sedimentary alterations from which we are able to modify our interpretations of previous climate conditions.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMGP32A..06M
- Keywords:
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- 1500 GEOMAGNETISM AND PALEOMAGNETISM;
- 1512 GEOMAGNETISM AND PALEOMAGNETISM / Environmental magnetism;
- 1540 GEOMAGNETISM AND PALEOMAGNETISM / Rock and mineral magnetism