* Astronomy

Blobrana · L

RE: El'gygytgyn crater

Blobrana · L

An international team of scientists led by Julie Brigham-Grette of the University of Massachusetts Amherst has received $3.2 million from the National Science Foundation (NSF) to fund an expedition to a polar lake in Siberia, which should yield data that will provide the most detailed record of past Arctic climate to date.
The research team’s destination is Lake El’gygytgyn, a lake of roughly nine miles across that was formed when a meteorite hurtled into northeastern Siberia around 3.6 million years ago. Unlike much of the Arctic, this lake was never covered by glaciers or ice sheets and thus has received a steady accumulation of sediment since the time of impact. Brigham-Grette and her team will collect deep cores of this sediment—cylindrical columns of dense muck that should provide a detailed narrative of the past climate of the Arctic.

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Position: 67.48329 °N, 172.12775 °E

Sediment piston cores from Lake El'gygytgyn, a 3.6 million year old meteorite impact crater in northeastern Siberia, have been analysed to extract a multi-proxy millennial-scale climate record extending to nearly 250 ka, with distinct fluctuations in sedimentological, physical, biochemical, and palaeoecological parameters.

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Blobrana · L

Central ring structure identified in one of the world's best-preserved impact craters
Authors: A.C. Gebhardt and F. Niessen

ABSTRACT
Seismic refraction and reflection data were acquired in 2000 and 2003 to study the morphology and sedimentary fill of the remote El'gygytgyn crater (Chukotka, northeastern Siberia; diameter 18 km).
The data allow a first insight into the deeper structure of this unique impact crater. Wide-angle data from sonobuoys reveal a five-layer model: a water layer, two lacustrine sedimentary units that fill a bowl-shaped apparent crater morphology consisting of an upper layer of fallback breccia with P-wave velocities of 3000 m/s, and a lower layer of brecciated bedrock (velocities >3600 m/s).
The lowermost layer shows a distinct anticline structure that, by analogy with other terrestrial and lunar craters of similar size, can be interpreted as a central ring structure. The El'gygytgyn crater exhibits a well-expressed morphology that is typical of craters formed in crystalline target rocks.

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Position: 67°29'34.73"N 172° 6'3.88"E

The impact crater has a diameter of 18km, and has been dated as 3.5 ± 0.5 million years old, (Pliocene).

Today it is filled with water and known as Lake El'gygytgyn. It is approximately 15 km across and 175 metres deep. The lake is of particular interest to scientists because it has never been covered by glaciers. This has allowed the uninterrupted build-up of a layer of sediment 400 metres thick at the bottom of the lake, which records information on historical climate change.