Occurrence of gas hydrate in the Chukchi plateau, Arctic

The Arctic MArine Geoscience Expedition (AMAGE) program led by the Korea Polar Research Institute (KOPRI) is a multidisciplinary undertaking to investigate the geological environment and methane release phenomena in the Arctic seas. The icebreaking research vessel (IBRV) Araon has carried out three expeditions in the Chukchi Plateau (CP) and the East Siberian Seas in 2016, 2018 and 2019. In the first 2016 expedition, a chain of topographic mounds (with the height of several tens meters and the width of hundreds meters) was identified by subbottom profiler and multibeam bathymetric survey in the western continental slope of the CP. Gas hydrate samples were first retrieved in the Araon Mound-6 among the mound structures in the CP and ESS areas during the expedition. The detailed morphology and subsurface structures of the mounds were mapped from the subsequent expeditions in 2018 and 2019. More gas hydrate samples were obtained in the Araon Mound-3 and Araon Mound-6 in these expeditions. To examine gas hydrate occurrence conditions, we conducted geophysical surveys including seismic (sparker in 2018 and multi-channel in 2019) and heat flow methods during these expeditions. The seismic profiles obtained using two seismic methods show very well-developed bottom simulating reflectors (BSRs) which are widespread on the western slope of the study area. The BSR depths detected on the seismic profiles are well coincided with the depths of the lower boundary of the gas hydrate stability zone calculated from the geothermal gradient of heat flow measurement.Arctic gas hydrates are considered to be vulnerable to the ongoing rapid Arctic warming. The AMAGE program will provide comprehensive understanding on poorly-known gas hydrate in the Arctic in the various research fields of geology, geophysics, geochemistry, biogeoscience, and oceanography.

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Seaward Dipping Reflectors Sequences (SDRs) mapping in the field of the Mendeleev Rise

10.5194/egusphere-egu2020-4912 ◽

2020 ◽

Author(s):

Elizaveta Rodina ◽

Anatoly Nikishin ◽

Ksenia Startseva ◽

Eugene Petrov

Keyword(s):

Continental Crust ◽

Lower Boundary ◽

High Amplitude ◽

Passive Margin ◽

Ca 125 ◽

Seismic Profiles ◽

Makarov Basin ◽

Half Graben ◽

Chukchi Plateau ◽

The Relationship

The report focuses on the strata of the Mendeleev Rise and adjacent Podvodnikov Basin, Makarov Basin, Toll Basin, and North Chukchi Basin together with Lomonosov Ridge and Chukchi Plateau. Eleven 2-D seismic profiles with a total length of 7540 km were interpreted. The uplifts within the study area are represented by asymmetric raised blocks of the crust with strongly rugged by half-graben structures. We found semi-continuous, from moderate to bright high-amplitude gently dipping reflectors similar to SDRs inside some half-grabens. The SDRs complexes distribute only in half-grabens. A few wedges with several kilometers thick can be distinguished here. The lower boundary of SDRs does not clearly trace. The relationship with underlying complexes is uncertain.&#160; SDRs top is bright enough and interpreted as an angular unconformity, that is progressively onlapped by overlying sediments. Top of SDRs probably coincides with rift-postrift boundary age of 110-100 Ma.&#160; We traced the distribution and direction of SDRs and made a map. SDRs dip from the central axis of Mendeleev Ridge in opposite directions &#8211; toward to Toll and Podvodnikov basins. In the central part of Podvodnikov and Toll basins are recognized small raised blocks of continental crust to which anti-directional SDRs converge. The nature of this rises can be explained by tectonic uplift. Thus, SDRs complexes dip symmetrically in two directions from the Mendeleev Rise. Two-directional SDRs also occur in conjugate Podvodnikov and Toll basins. They dip from the Mendeleev Rise and from the Lomonosov Terrace and the Chukchi Plateau, respectively. The SDRs occur on the hyperextension continental crust complex and accompany magmatism on volcanic passive margin (VPM). We propose that the Mendeleev Rise was formed as two-directional VPM, and the Lomonosov Terrace and the Chukchi Plateau also was formed as one-directional VPM. The Mendeleev Rise was formed simultaneously with Podvodnikov, Toll and North Chukchi basins ca. 125-100 Ma because of extensional tectonics. We also assume that the Makarov Basin (with obvious half-graben structures) could form simultaneously with the Nautilus Basin. This work was supported by RFBR grants (18-05-70011 and 18-05-00495).

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Arctic Ocean Gas Hydrate Stability in a Changing Climate

Journal of Geological Research ◽

10.1155/2013/783969 ◽

2013 ◽

Vol 2013 ◽

pp. 1-10 ◽

Cited By ~ 14

Author(s):

Michela Giustiniani ◽

Umberta Tinivella ◽

Martin Jakobsson ◽

Michele Rebesco

Keyword(s):

Arctic Ocean ◽

Sea Level ◽

Gas Hydrates ◽

Gas Hydrate ◽

Arctic Region ◽

Geothermal Gradient ◽

The Arctic ◽

Ocean Bottom ◽

The Arctic Ocean ◽

Hydrate Stability

Recent estimations suggest that vast amounts of methane are locked in the Arctic Ocean bottom sediments in various forms of gas hydrates. A potential feedback from a continued warming of the Arctic region is therefore the release of methane to the atmosphere. This study addresses the relationship between a warming of the Arctic ocean and gas hydrate stability. We apply a theoretical model that estimates the base of the gas hydrate stability zone in the Arctic Ocean considering different bottom water warming and sea level scenarios. We model the present day conditions adopting two different geothermal gradient values: 30 and 40°C/km. For each geothermal gradient value, we simulate a rise and a decrease in seafloor temperature equal to 2°C and in sea level equal to 10 m. The results show that shallow gas hydrates present in water depths less than 500 m would be strongly affected by a future rise in seafloor temperature potentially resulting in large amounts of gas released to the water column due to their dissociation. We estimate that the area, where there could be complete gas hydrate dissociation, is about 4% of the area where there are the conditions for gas hydrates stability.

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The differences between the measured heat flow and BSR heat flow in the Shenhu gas hydrate drilling area, northern South China Sea

Energy Exploration & Exploitation ◽

10.1177/0144598718793907 ◽

2018 ◽

Vol 37 (2) ◽

pp. 756-769 ◽

Cited By ~ 2

Author(s):

Miao Dong ◽

Jian Zhang ◽

Xing Xu ◽

Shi-Guo Wu

Keyword(s):

Heat Flow ◽

Gas Hydrate ◽

Northern South China Sea ◽

Geothermal Gradient ◽

Topographic Effects ◽

Fluid Flux ◽

Flow Measurements ◽

Upward Migration ◽

Bottom Simulating Reflector ◽

The Impact

Temperature is an important factor that affects the stability of a gas hydrate. To investigate the geothermal characteristics in the gas hydrate drilling area, heat flow measurements were performed in the surrounding area of the SH2 well. The measured heat flow was compared with the bottom simulating reflector heat flow, which was calculated by using the depth of the bottom simulating reflector in the seismic data. Combined with the geological background of the Shenhu drilling area, we analyzed the reasons for the differences between the measured heat flow and the bottom simulating reflector heat flow. In addition to analyzing the differences caused by the calculation parameters, we calculated the 3-D topographic effects on the measured heat flow by using the finite element numerical simulation method. The results show that the measured heat flow was seriously affected by the topography and produced a −50–30% error in the study area. After terrain correction of the measured heat flow, we found that the data were greater than the bottom simulating reflector heat flow at almost all sites. Therefore, we considered the impact of fluid activity and calculated the relationship among the thickness of the gas hydrate stability zone, the fluid flux and the heat flow. The results show that when the base of the bottom simulating reflector was at a certain depth, the geothermal gradient increased with the increasing upward migration of the fluid flux. Therefore, when upward fluid migration is present, the measured heat flow in the seafloor sediments is greater than the heat flow in the deep layers. In general, we showed that the influences of the topography and fluid activity are the main factors leading to the inconsistency between the bottom simulating reflector heat flow and the measured heat flow in the Shenhu gas hydrate drilling area.

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Diatoms and aquatic palynomorphs in the sediments of the Eurasian Arctic seas and their significance for paleooceanological investigations in the Arctic

Issues of modern algology (Вопросы современной альгологии) ◽

10.33624/2311-0147-2019-2(20)-246-251 ◽

2019 ◽

pp. 246-251

Author(s):

Yelena I. Polyakova ◽

Yekaterina I. Novichkova ◽

Tatiana S. Klyuvitkina ◽

Elizaveta A. Agafonova ◽

Irina M. Kryukova

Keyword(s):

Bering Sea ◽

Surface Sediments ◽

Sea Water ◽

The Arctic ◽

Marginal Filter ◽

Arctic Seas ◽

Hydrological Parameters ◽

The Arctic Ocean ◽

Long Term Studies

Presented the results of long-term studies of diatoms and aquatic palynomorphs in surface sediments of the Arctic seas and the possibility of their use for the reconstructions of paleocirculation water masses, advection of Atlantic and Bering sea water into the Arctic ocean, changes in the river runoff to the seas, sedimentary processes in the marginal filter of the largest rivers, seasonal sea ice cover and other hydrological parameters.

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Comparative Analysis of Oil Spill Response Methods in the Arctic Seas

Occupational Safety in Industry ◽

10.24000/0409-2961-2020-3-18-26 ◽

2020 ◽

pp. 18-26

Author(s):

A.A. Gorbunov ◽

◽

S.I. Shepelyuk ◽

A.G. Nesterenko ◽

K.I. Drapey ◽

...

Keyword(s):

Comparative Analysis ◽

Oil Spill ◽

The Arctic ◽

Arctic Seas ◽

Oil Spill Response

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THE APPROACHES TO THE SOLVING ENVIRONMENTAL AND ECONOMIC PROBLEMS OF SUSTAINABLE DEVELOPMENT ON THE SHELF OF THE ARCTIC SEAS OF THE RUSSIAN FEDERATION

Proceedings of International Conference "Managinag risks to coastal regions and communities in a changinag world" (EMECS'11 - SeaCoasts XXVI) ◽

10.21610/conferencearticle_58b43152c06d7 ◽

2017 ◽

Author(s):

Alexander Krivichev ◽

Alexander Krivichev

Keyword(s):

Continental Shelf ◽

Oil Spill ◽

The Arctic ◽

Marginal Stability ◽

Environmental Benefit ◽

Arctic Seas ◽

Dynamic Simulations ◽

Economic Problems ◽

Technogenic Loads ◽

Oil Spill Response

Russian Arctic shelf - rich larder of the hydrocarbons, at the same time Northern Sea Route (NSR) - a strategically important route for transporting them. The extraction and the transportation of the hydrocarbons along the NSR requires the solution of a number of ecological and economic problems in the first place to ensure environmental and technogenic safety. For the solving of these problems on the continental shelf it is required a system of comprehensive measures: - the development of the regulatory framework for environmental support oil and gas projects; - the introduction and use of integrated methods for monitoring environmental conditions at the sites of technogenic loads on the shelf of the Arctic seas, including the use of drones; - creating different models for assessing the marginal stability of ecosystems to technogenic loads during production and transportation of hydrocarbons on the continental shelf based on systems of dynamic simulations; - the development and use of sensitivity maps of coastal areas of the Arctic seas during oil spill response; - accounting of the results of the analysis of the total environmental benefit in the development of oil spill response plans; - application of the principle of "zero" resetting, due to the high fishery valuation in Barents and Kara seas and the conservation of marine biological resources.

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Transmission of parasites in the coastal waters of the Arctic seas and possible effect of climate change

Biology Bulletin ◽

10.1134/s1062359016110054 ◽

2016 ◽

Vol 43 (9) ◽

pp. 1129-1147 ◽

Cited By ~ 4

Author(s):

K. V. Galaktionov

Keyword(s):

Climate Change ◽

Coastal Waters ◽

The Arctic ◽

Arctic Seas

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The Reproductive Biology of Ophiacantha Bidentata (Echinodermata: Ophiuroidea) From The Rockall Trough

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315400020099 ◽

1982 ◽

Vol 62 (1) ◽

pp. 45-55 ◽

Cited By ~ 21

Author(s):

P. A. Tyler ◽

J. D. Gage

Keyword(s):

Reproductive Biology ◽

Deep Water ◽

Larval Stage ◽

North Pacific ◽

Deep Sea ◽

Direct Development ◽

The Arctic ◽

Shallow Waters ◽

Arctic Seas ◽

Rockall Trough

INTRODUCTIONOphiacantha bidentata (Retzius) is a widespread arctic-boreal ophiuroid with a circumpolar distribution in the shallow waters of the Arctic seas and penetrating into the deep sea of the.North Atlantic and North Pacific (Mortensen, 1927, 1933a; D'yakonov, 1954). Early observations of this species were confined to defining zoogeo-graphical and taxonomic criteria including the separation of deep water specimens as the variety fraterna (Farran, 1912; Grieg, 1921; Mortensen, 1933a). Mortensen (1910) and Thorson (1936, pp. 18–26) noted the large eggs (o.8 mm diameter) in specimens from Greenland and Thorson (1936) proposed that this species had ‘big eggs rich in yolk, shed directly into the sea. Much reduced larval stage or direct development’. This evidence is supported by observations of O. bidentata from the White and Barents Seas (Semenova, Mileikovsky & Nesis, 1964; Kaufman, 1974)..

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