Permafrost, Gas Hydrates and Gas Seeps in the Central Part of the Laptev Sea

2021 ◽  
Vol 500 (1) ◽  
pp. 766-771
Author(s):  
V. I. Bogoyavlensky ◽  
A. V. Kishankov ◽  
A. G. Kazanin
Keyword(s):  
Gas Hydrates ◽  
Laptev Sea ◽  
The Laptev Sea ◽  
Gas Seeps

scholarly journals Factors Affecting the Formation and Evolution of Permafrost and Stability Zone of Gas Hydrates: Case Study of the Laptev Sea

Geosciences ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 504
Author(s):  
Tatiana V. Matveeva ◽  
Valery D. Kaminsky ◽  
Anastasiia A. Semenova ◽  
Nikolai A. Shchur
Keyword(s):  
Gas Hydrates ◽  
Gas Hydrate ◽  
Hydrate Formation ◽  
Laptev Sea ◽  
Permafrost Degradation ◽  
Associated Gas ◽  
Gas Hydrate Formation ◽  
The Impact ◽  
The Laptev Sea ◽  
Hydrate Stability

The key factors controlling the formation and dynamics of relicpermafrost and the conditions for the stability of associated gas hydrates have been investigated using numerical modeling in this work. A comparison was made between two scenarios that differed in the length of freezing periods and corresponding temperature shifts to assess the impact on the evolution of the permafrost–hydrate system and to predict its distribution and geometry. The simulation setup included the specific heat of gas hydrate formation and ice melting. Significantly, it was shown that the paleoscenario and heat flows affect the formation of permafrost and the conditions for gas hydrate stability. In the Laptev Sea, the minimum and maximum predicted preservation times for permafrost are 9 and 36.6 kyr, respectively, whereas the presence of conditions consistent with methane hydrate stability at the maximum permafrost thickness is possible for another 25.9 kyr. The main factors influencing the rate of permafrost degradation are the heat flow and porosity of frozen sediments. The rates of permafrost thawing are estimated to be between 1 and 3 cm/yr. It is revealed that the presence of gas hydrates slows the thawing of the permafrost and feeds back to prolong the conditions under which gas hydrates are stable.

scholarly journals Earth degassing in the Arctic: comprehensive analysis of factors of powerful gas emission in the Laptev Sea

2021 ◽  
Vol 11 (2) ◽  
pp. 178-194
Author(s):  
V.I. Bogoyavlensky ◽  
◽  
A.G. Kazanin ◽  
A.V. Kishankov ◽  
G.A. Kazanin ◽  
...  
Keyword(s):  
Gas Hydrates ◽  
Average Distance ◽  
Comprehensive Analysis ◽  
The Arctic ◽  
Laptev Sea ◽  
Gas Emission ◽  
Bottom Simulating Reflector ◽  
Seismic Sections ◽  
First Time ◽  
The Laptev Sea

Interpretation was conducted for 28 CDP seismic time sections with total length of 5930 km acquired by JSC “MAGE” in the Central Laptev Area, where a zone of powerful gas emission had been discovered earlier. 519 anomalous objects were revealed in near-bottom deposits with an average distance on seismic lines of 11,4 km, potentially connected with accumulations of gas and its migration paths. As a result of comprehensive analysis, for the first time, connection of gas seeps with deep-seated faults in the study area was justified. Highly likely forecast was made that in the area of the discovered seeps (seafloor depths from 50—60 m to 110 m), permafrost and gas hydrates are absent, and the seeps are caused by direct migration of gas from great depths. On the continental slope of the Laptev Sea, a bottom simulating reflector (BSR) was distinguished in CDP seismic sections, associated with the base of gas hydrates.

scholarly journals Composition of Sedimentary Organic Matter across the Laptev Sea Shelf: Evidences from Rock-Eval Parameters and Molecular Indicators

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3511
Author(s):  
Elena Gershelis ◽  
Andrey Grinko ◽  
Irina Oberemok ◽  
Elizaveta Klevantseva ◽  
Natalina Poltavskaya ◽  
...  
Keyword(s):  
Organic Matter ◽  
Surface Sediments ◽  
Continental Margins ◽  
Laptev Sea ◽  
Lena River ◽  
Nearshore Sediments ◽  
Rock Eval ◽  
Molecular Indicators ◽  
Sedimentation Regime ◽  
The Laptev Sea

Global warming in high latitudes causes destabilization of vulnerable permafrost deposits followed by massive thaw-release of organic carbon. Permafrost-derived carbon may be buried in the nearshore sediments, transported towards the deeper basins or degraded into the greenhouse gases, potentially initiating a positive feedback to climate change. In the present study, we aim to identify the sources, distribution and degradation state of organic matter (OM) stored in the surface sediments of the Laptev Sea (LS), which receives a large input of terrestrial carbon from both Lena River discharge and intense coastal erosion. We applied a suite of geochemical indicators including the Rock Eval parameters, traditionally used for the matured OM characterization, and terrestrial lipid biomarkers. In addition, we analyzed a comprehensive grain size data in order to assess hydrodynamic sedimentation regime across the LS shelf. Rock-Eval (RE) data characterize LS sedimentary OM with generally low hydrogen index (100–200 mg HC/g TOC) and oxygen index (200 and 300 CO2/g TOC) both increasing off to the continental slope. According to Tpeak values, there is a clear regional distinction between two groups (369–401 °C for the inner and mid shelf; 451–464 °C for the outer shelf). We suggest that permafrost-derived OM is traced across the shallow and mid depths with high Tpeak and slightly elevated HI values if compared to other Arctic continental margins. Molecular-based degradation indicators show a trend to more degraded terrestrial OC with increasing distance from the coast corroborating with RE results. However, we observed much less variation of the degradation markers down to the deeper sampling horizons, which supports the notion that the most active OM degradation in LS land-shelf system takes part during the cross-shelf transport, not while getting buried deeper.

Results of permafrost modelling of the lowlands and shelf of the Laptev Sea Region, Russia

2001 ◽  
Vol 12 (2) ◽  
pp. 191-202 ◽  
Author(s):  
Nikolai N. Romanovskii ◽  
Hans-W. Hubberten
Keyword(s):  
Laptev Sea ◽  
The Laptev Sea

Sea-ice processes in the Laptev Sea and their importance for sediment export

1997 ◽  
Vol 17 (2) ◽  
pp. 205-233 ◽  
Author(s):  
H. Eicken ◽  
E. Reimnitz ◽  
V. Alexandrov ◽  
T. Martin ◽  
H. Kassens ◽  
...  
Keyword(s):  
Sea Ice ◽  
Laptev Sea ◽  
Sediment Export ◽  
The Laptev Sea

scholarly journals Ocean-Bottom Seismographs Based on Broadband MET Sensors: Architecture and Deployment Case Study in the Arctic

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 3979
Author(s):  
Artem A. Krylov ◽  
Ivan V. Egorov ◽  
Sergey A. Kovachev ◽  
Dmitry A. Ilinskiy ◽  
Oleg Yu. Ganzha ◽  
...  
Keyword(s):  
Site Response ◽  
The Arctic ◽  
Laptev Sea ◽  
Ocean Bottom ◽  
Arctic Seas ◽  
Shirshov Institute ◽  
Study Results ◽  
Ocean Bottom Seismographs ◽  
The Laptev Sea

The Arctic seas are now of particular interest due to their prospects in terms of hydrocarbon extraction, development of marine transport routes, etc. Thus, various geohazards, including those related to seismicity, require detailed studies, especially by instrumental methods. This paper is devoted to the ocean-bottom seismographs (OBS) based on broadband molecular–electronic transfer (MET) sensors and a deployment case study in the Laptev Sea. The purpose of the study is to introduce the architecture of several modifications of OBS and to demonstrate their applicability in solving different tasks in the framework of seismic hazard assessment for the Arctic seas. To do this, we used the first results of several pilot deployments of the OBS developed by Shirshov Institute of Oceanology of the Russian Academy of Sciences (IO RAS) and IP Ilyinskiy A.D. in the Laptev Sea that took place in 2018–2020. We highlighted various seismological applications of OBS based on broadband MET sensors CME-4311 (60 s) and CME-4111 (120 s), including the analysis of ambient seismic noise, registering the signals of large remote earthquakes and weak local microearthquakes, and the instrumental approach of the site response assessment. The main characteristics of the broadband MET sensors and OBS architectures turned out to be suitable for obtaining high-quality OBS records under the Arctic conditions to solve seismological problems. In addition, the obtained case study results showed the prospects in a broader context, such as the possible influence of the seismotectonic factor on the bottom-up thawing of subsea permafrost and massive methane release, probably from decaying hydrates and deep geological sources. The described OBS will be actively used in further Arctic expeditions.

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