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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