T. Matveeva, G. Cherkashov

VNIIOkeangeologiaVNIIOkeangeologia

RUSALCA-2012 Expedition RUSALCA-2012 Expedition (Russian-American Long-term Census (Russian-American Long-term Census

of the Arcticof the Arctic))::Initial geological results Initial geological results

Institute for Geology and Mineral Resources of the Ocean (I.S. Gramberg VNIIOkeangeologia), St. Petersburg, Russia

RUSALCA General InfoRUSALCA General Info(Russian-American Long Term Census of the Arctic) (Russian-American Long Term Census of the Arctic)

CountryCountry OrganisationOrganisation

RussiaRussia Group Alliance, VNIIOkeangeologia, Group Alliance, VNIIOkeangeologia, POI RAS, ZIN RAS, INMI RAS, POI RAS, ZIN RAS, INMI RAS, FERHRI, AARI, Nav-Hydrographic FERHRI, AARI, Nav-Hydrographic institute RF MoD,institute RF MoD, SIO RASSIO RAS

USAUSA NOAANOAA, U. of Alaska, U. of , U. of Alaska, U. of Washington, WHOI, Point Stephens, Washington, WHOI, Point Stephens, U. of Maryland, U. of Maryland,

CanadaCanada Reuters, BIOSReuters, BIOS

Great Great BritainBritain

U. of WashingtonU. of Washington

KoreaKorea KOPRIKOPRI

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) – *RUSALCA (RUS) – MERMAID (ENG)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: http://oceanexplorer.noaa.gov/explorations/12arctic/welcome.html

3 m length 3 m length hydraulic corer was used for the sediment corer was used for the sediment samplingsampling

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 fromMore then 50 scientists and specialists fromRussia, USA, Canada, Great Britain and Russia, USA, Canada, Great Britain and

KoreaKorea

Background:Background:RUSALCA-2009 coring results and seismic dataRUSALCA-2009 coring results and seismic data

23

1

Russia

USA

Arctic Ocean

Pockmarks

Bering Sea

Area of interest in 2012 -

extension of Gerald Canyon

off Wrangel Island

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

Herald C

anyon

Herald C

anyon Gouges more than

Gouges more than 1200 m1200 m

More than

More than 1200 m1200 m

10-200 m wide

10-200 m wide

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

GAS

NO coring stations at this site

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

Corg values vary widely ranging from 0.1-2.8%, average - 1.21% (Stein, 2008).

Max CH4 content is 17.4 µM/dm3 - 30 times higher than the average methane content in the sediment of the southern Chukchi Sea (0.2-0.8 µM/dm3).

CH4 content by Alexander Savvichev, IO RASCH4 content by Alexander Savvichev, IO RAS

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

Anomalous hydrocarbon gases content in bottom sediment (cm3/kg)1 – less 0.005; 2 – from 0.005 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 cm3/kg

Organic carbon content in bottom sediment (%)

Yashin, Kim, 1994

Background: VNIIO own data on gases content in sediment

Area of interestoffshore Chukchi

Peninsula

Offshore Chukchi PeninsulaOffshore 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?)

- H2S odor

Evidences of AOM

Way forwardWay 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!!!