Arctic Climate History Since 3.6 Million Years 
New - Expedition Report - New


Martin Melles
Olaf Juschus

Julie Brigham-Grette
University of Massachusetts, USA
Pavel S. Minyuk, Olga Yu. Glushkova
NEISRI, Magadan, Russia
Christian Koeberl
University Vienna, Austria
Dimitri Yu. Bolshiyanov, Grigory B. Fedorov
Arctic and Antarctic Research Institute, St. Petersburg
Hans-W. Hubberten, Frank Niessen, Conny Kopsch
Alfred-Wegener-Institut, Potsdam und Bremerhaven
Norbert Nowaczyk
GeoForschungsZentrum Potsdam
Jan Michael Lange
Saechs. Naturwiss. Sammlung, Dresden

Funding:
German Federal Ministry for Education and Research (BMBF)


 
Background
Lake El´gygytgyn, located in central Chukotka, NE Siberia, is a 3.6 million year old impact crater lake with a diameter of 12 km and a water depth of 170 m (detailed map). During the last 7 years the sedimentary record of the lake has become a major focus of multi-disciplinary multi-national paleoclimatic research. Recently, the International Continental Scientific Drilling Program (ICDP) has provided funding for a drilling operation on the lake and in its permafrost catchment in winter 2007/08. A full-length sediment core from Lake El´gygytgyn would yield a complete record of Arctic climate evolution, back one million years prior to the first major glaciation of the Northern Hemisphere. 

 
map

Past Work and Results
A 12.9 m long sediment core retrieved from the deepest part of the lake in 1998 revealed a basal age of approx. 250 ka, confirmed the lack of glacial erosion, and underlined the sensitivity of this lacustrine environment to reflect high-resolution climatic change on Milankovitch and sub-Milankovitch time scales. Four sediment units were distinguished, reflecting relatively warm, peak warm, cold and dry, and cold but more moist climates (sketch of climate modes).

Based on these promising results a second expedition to Lake El´gygytgyn was carried out  in summer 2000, focusing on seismic investigations of the entire sediment record. In addition, extensive funding was provided by the German Federal Ministry for Education and Research (BMBF) to the University Leipzig and the Alfred Wegener Institute. This allowed to conduct a third expedition in spring and summer 2003.



Expedition Report: 145 pages (high quality PDF 28,5 Mb; low quality PDF 10,5 Mb)

On this expedition, samples and data became available, which supply information on the modern processes of sediment formation under known, i.e. measured climatic and environmental conditions (e.g., meteorological und hydrological data, rock samples, eolian, fluvial and limnic sediments), and on the history in the lake catchment (e.g., permafrost sediments, Ground Penetrating Radar (GPR) survey, permafrost temperature measurements). A 16.7 m long sediment core taken in the lake center confirmed the reproducibility of the record and dates to nearly 300 ka. Additional cores from the western lake have shown that the formation of debris flows at the slope is associated with partial erosion of the underlying sediments, and leads to the development of suspension clouds, whose deposition generally takes place all over the lake as ´pelagic rain´ without erosion (sketch of slope sedimentation). Hence, the sediment records deposited in the central lake during at least the past 300 ka are continuous, and the existing cores represent the longest continuous climate records as yet available from the Arctic continent.

Seismic investigation carried out during the expedtions in 2000 and 2003 revealed a depth-velocity model of brecciated bedrock overlain by a suevite layer, in turn overlain by two lacustrine sedimentary units up to 350 m in thickness.

cross section
high resolution crater cross section

The upper well-stratified sediment unit appears undisturbed apart from intercalation with the debris flows near the slopes. Based on extrapolation of sedimentation rates the entire Quaternary and possibly parts of the late Tertiary record are reflected by the 170 m thick unit one, whilst the earliest history of the lake is presumably represented with a higher sedimentation rate by unit two. There is no evidence for glacial erosion or complete lake drying in the entire sedimentary record.

In March 2004 an international El´gygytgyn Lake Workshop, funded by the BMBF, was held in Leipzig (group foto). On this workshop first results of the expedition in 2003 were presented, and the future work coordinated (program and abstracts, PDF 6,5Mb). Following an ICDP Pre-Proposal submitted in Jan. 2004, a full proposal for partial funding of the operational costs for the deep drilling campaign in the El´gygytgyn Crater was submitted in Jan. 2005.

ICDP Full Proposal: 84 pages (high quality PDF 10 Mb; low quality PDF 3 Mb)

 

Perspectives
Until spring 2006 a number of proposals shall be submitted to national funding agencies in Germany, the US, Russia and other countries for the remaining operational costs for the drilling campaign as well as for the scientific investigation of the drill cores.

Coring shall then be carried out in winter 2007/08 at two sites from the lake ice cover and at one site in the western lake catchment (see cross section). Coring objectives include replicate cores of 630 m length to retrieve a continuous paleoclimate record from the deepest part of the lake and into the underlying impact breccias and bedrock. The impact rocks offer the planetary community with the opportunity to study a well preserved crater uniquely found in igneous rocks like those on Mars. The additional core to ca. 200 m into permafrost from the adjacent catchment will allow us to test ideas about arctic permafrost history and sediment supply to the lake since the time of impact.