Pliocene to Holocene geomorphic evolution and paleogeography of the El’gygytgyn Lake region,NE Russia |
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Authors: | O Yu Glushkova V N Smirnov |
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Institution: | (1) North-East Interdisciplinary Scientific Research Institute FEB RAS, 16 Portovaya Street, 685000 Magadan, Russia |
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Abstract: | Geomorphic, lithologhic, and stratigraphic field studies as well as pollen data and mineralogical study have been used to
propose Pliocene and Pleistocene paleogeographic reconstructions of the El’gygytgyn meteorite crater area. The moment of impact
is recorded above the early Pliocene hill denudation plain as a “chaotic horizon” consisting of fragments of impactite rocks.
This chaotic horizon lies between layers of late Pliocene alluvial sediments. During the second half of the late Pliocene,
the region was tectonically active, when the Anadyr lowland was uplifted causing alluvial sediments to accumulate in the basins
to the south of the crater. Regional climatic cooling, which supported the spread of tundra and the formation of permafrost
is characteristically to late Pliocene. The 35–40 m high terrace that roughly follows the 530 m contour interval along the
Enmyvaam River formed during the middle Pleistocene. This terrace represents the maximum lake level. Erosion and incision
of the upper Enmyvaam River increased due to another wave of uplift. Additionally, El’gygytgyn Lake discharge increased causing
lake level to begin to drop in the Middle Pleistocene. Cooling continued, which led to the development of herb-dominated arctic
tundra. middle and late Pleistocene glaciations did not reach the El’gygytgyn lake region. The 9–11 m high lacustrine terrace
was formed around the lake during the late Pleistocene and the 2–3 m high lacustrine terrace formed later during the Holocene.
During the last 5000 years, the lake level has continued to drop as the modern coastline developed.
This is the third 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. |
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Keywords: | El’ gygytgyn Lake Impact crater Paleogeography Paleoclimate Pliocene Pleistocene Holocene Terraces Pollen Chronology NE Russia |
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