T. Matveeva, G. Cherkashov VNIIOkeangeologia RUSALCA-2012 Expedition (Russian-American Long-term Census (Russian-American Long-term Census of the Arctic): Initial geological results Institute for Geology and Mineral Resources of the Ocean (I.S. Gramberg VNIIOkeangeologia), St. Petersburg, Russia

RUSALCA General Info (Russian-American Long Term Census of the Arctic) CountryOrganisationRussia Group Alliance, VNIIOkeangeologia, POI RAS, ZIN RAS, INMI RAS, FERHRI, AARI, Nav-Hydrographic institute RF MoD, SIO RAS USA NOAA, U. of Alaska, U. of Washington, WHOI, Point Stephens, U. of Maryland, Canada Reuters, BIOS Great Britain U. of Washington KoreaKOPRI Stemming from a 2003 Memorandum of Understanding for World Ocean and Polar Regions Studies between NOAA and the Russian Academy of Sciences, serveral successful collaborative U.S – Russian Federation oceanographic expedition to the Arctic seas regions shared by both countries were performed. The aims included monitoring the flux of fresh and salt water as well as establishing benchmark information about the distribution and migration patterns of the life in the Bering Strait and the Chukchi Sea by using the biological, geological, chemical and physical oceanographic sampling methods. These seas and the life within are thought to be particularly sensitive to global climate change. *RUSALCA (RUS) – MERMAID (ENG)

On August 28, scientists onboard the Russian research vessel Professor Khromov left Nome, Alaska, to commence the second leg of the 2012 Russian- American Long-term Census of the Arctic (RUSALCA) cruise. This is the ninth year that RUSALCA scientists conducted long-term research to better understand the causes and consequences of environmental change in the fragile Arctic environment. Scientists had returned to Nome on September 17. Learn more: ctic/welcome.html

3 m length corer was used for the sediment sampling 3 m length hydraulic corer was used for the sediment sampling RUSALCA-2012 geological team The aims of the studies were revelation of the hydrocarbons (mainly methane) indications presence in the uppermost sediment of the Chukchi Sea (high organic matter content, gaseous sediment structures, anomalous hydrogeochemical sections, intensive sulphate-reduction processes) at the study areas selected on the base of the results of the previous RUSALCA expeditions. More then 50 scientists and specialists from Russia, USA, Canada, Great Britain and Korea

Background: RUSALCA-2009 coring results and seismic data Russia USA Arctic Ocean Pockmarks Bering Sea Area of interest in extension of Gerald Canyon off Wrangel Island

Extension of the Herald Canyon: gas saturated sediment distribution along the seismic lines

Herald Canyon Gouges more than 1200 m More than 1200 m m wide Extension of the Herald Canyon: gas saturated sediment distribution along the seismic lines

GAS NO coring stations at this site Extension of the Herald Canyon: gas saturated sediment distribution along the seismic lines

C org values vary widely ranging from %, average % (Stein, 2008). Max CH 4 content is 17.4 µM/dm times higher than the average methane content in the sediment of the southern Chukchi Sea ( µM/dm 3 ). CH4 content by Alexander Savvichev, IO RAS Extension of the Herald Canyon: gas saturated sediment distribution along the seismic lines

Anomalous hydrocarbon gases content in bottom sediment (cm 3 /kg) 1 – less 0.005; 2 – from to 0.01; 3 – from 0.01 to 0.05; 4 – from 0.05 to 0.1; 5 – from 0.1 to 1.0; 6 – > 1.0 cm 3 /kg Organic carbon content in bottom sediment (%) Yashin, Kim, 1994 Background: VNIIO own data on gases content in sediment Area of interest offshore Chukchi Peninsula Offshore Chukchi Peninsula

Geological studies during RUSALCA-2012 cruise in the Chukchi Sea were carried out along two submeridional profiles with detailed sampling line within northern extension of the Herald Canyon. Hydraulic corers Box-corers

Totally 39 geological stations (28 box-corers and 11 hydraulic corers) were taken during the cruise at the water depths from 28 to 110 m. Maximum core recovery was 274 cm. After the hydraulic corer retrieval the cores were split along the section, sediments were described and subsampled for the further analysis in the laboratories onland. Lithological description of sediments was carried out accordingly to routine procedure.

Core HC-4 Field observations Sediments recovered within the study area were represented by dense olive-gray or dark-gray clays and silty-clays with different amount small sand admixture. The age of the sediments is Holocene- Pleistocene. - numerous hydrotroilite lenses, bands, and interlayers (high organic matter content) - gravel-containing horizons (slump?), high rates of sedimentation - very dense sediment in the bottom part of the cores (hydrocarbon seal?) - H 2 S odor Evidences of AOM

Way forward Analyses of the obtained samples: - headspace gas - pore water chemistry - isotope studies (oxygen an hydrogen isotopes) in water - buried carbonate shell study - microbiological investigations - Corg content RUSALCA -2014

Thank you for the attention!!!