Inorganic geochemistry of El’gygytgyn Lake sediments (northeastern Russia) as an indicator of paleoclimatic change for the last 250 kyr |
| |
| Authors: | P S Minyuk J Brigham-Grette M Melles V Ya Borkhodoev O Yu Glushkova |
| |
| Institution: | (1) North-East Interdisciplinary Science Research Institute, FEB RAS, 685000 Magadan, Russia;(2) Department of Geosciences, University of Massachusetts, Amherst, MA 01003, USA;(3) Institute for Geophysics and Geology, University Leipzig, D-04103 Leipzig, Germany |
| |
| Abstract: | The inorganic geochemistry of sediments from El’gygytgyn Lake shift in phase with interpreted paleoclimatic fluctuations seen
in the record over the past 250 ka. Warm periods, when the lake was seasonally ice free and fully mixed, are characterized
by increased concentrations of SiO2, CaO, Na2O, K2O, and Rb, by decreased contents of TiO2, Fe2O3, Al2O3, and MgO, and by a lower chemical index of alteration (CIA). Increased levels of SiO2 reflect increases in limnic productivity whereas many of the other elements and the CIA likely reflect increased hydrological
activity coincident with an increase in coarser sand and silt content and a decrease in clay mineral content. For cold/cooler
periods when perennial lake ice cover lead to a stratifed water column and anoxic bottom waters, the opposite is generally
observed suggesting a decrease in hydrological activity and an increase in post-depositional chemical alteration.
Peaks in P2O3 and MnO, coincident with an increased abundance of vivianite, suggest possible linkages to the paleoproductivity of local
fish fauna regardless of climate change across the region surrounding Lake El’gygytgyn. Strontium is high in concentration
during warmer intervals and may also be linked to paleoproductivity. Enrichment of the post-Eemian portion of the sediment
record in niobium, and yttrium appears independent of glacial–interglacial change; rather it may reflect a gradual shift in
the geomorphology of the catchment, particularly the hydrology of large alluvial fans along the western side of the lake.
In contrast to some lake records, changes in Zr concentration over time suggests only a weak, if any, increase in eolian sediment
supply during colder periods.
This is the first in a series of eleven papers published in this special issue dedicated to initial studies of El'gygytgyn Crater Lake and
its catchment in NE Russia. Julie Brigham-Grette, Martin Melles, Pavel Minyuk were guest editors of this special issue. |
| |
| Keywords: | El’ gygytgyn Lake Chukotka Inorganic geochemistry Late Quaternary Paleoclimate |
| 本文献已被 SpringerLink 等数据库收录！ |
|
