scholarly journals Methane-Derived Authigenic Carbonates on the Seafloor of the Laptev Sea Shelf

2021 ◽  
Vol 8 ◽  
Author(s):  
Marina D. Kravchishina ◽  
Alla Yu Lein ◽  
Mikhail V. Flint ◽  
Boris V. Baranov ◽  
Alexey Yu Miroshnikov ◽  
...  
Keyword(s):  
Microbial Mats ◽  
Authigenic Carbonate ◽  
Cold Seep ◽  
Arctic Shelf ◽  
Laptev Sea ◽  
Carbonate Precipitation ◽  
Carbonate Formation ◽  
Siberian Arctic ◽  
Seep Carbonate ◽  
The Laptev Sea

Seafloor authigenic carbonate crusts are widespread in various oceanic and marine settings, excluding high-latitude basins that are corrosive to carbonate precipitation. Newly formed carbonate formations are relatively rare in modern Arctic marine sediments. Although the first-order principles of seep carbonate formation are currently quite well constrained, little is known regarding the duration or mode of carbonate formation in the Siberian Arctic shelf. Large (massive slabs or blocks) and small crusts that were micrite cemented have been recently discovered on the seafloor of the Siberian Arctic seas within the area of known seep activity in the outer Laptev Sea shelf. Cold methane seeps were detected in the area due to the presence of an acoustic anomaly in the water column (gas flares). Microbial mats, methane gas bubbles, and carbonate crusts were observed using a towed camera platform. Here, we report new geochemical and mineralogical data on authigenic shallow Siberian Arctic cold-seep carbonate crusts to elucidate its genesis. The Laptev Sea carbonate crusts mainly consist of high-Mg calcite (up to 23 mol % MgCO3). The δ13C values in carbonates range significantly (from –40.1 to –25.9‰ VPDB), while the δ18O values vary in a narrow range (+4.4 ± 0.2‰ VPDB). The δ13C values of Corg that was determined from carbonates range from –40.2 to –31.1‰ VPDB. Using the isotope data and taking into account the geological setting, we consider that not only microbial but possibly thermogenic methane participated in the authigenic carbonate precipitation. Carbonate crust formation occurred below the water/sediment interface of the shallow Siberian Arctic shelf as a result of gas hydrate dissociation during Holocene warming events. The studied carbonate crusts were exhumated after precipitation into shallow subsurface shelf sediments.

Mechanisms of Late Pleistocene authigenic Fe–Mn-carbonate formation at the Laptev Sea continental slope (Siberian Arctic)

arktos ◽  
2018 ◽  
Vol 4 (1) ◽  
Author(s):  
Elizaveta Logvina ◽  
Alexeу Krylov ◽  
Еkaterina Taldenkova ◽  
Valentina Blinova ◽  
Vladimir Sapega ◽  
...  
Keyword(s):  
Continental Slope ◽  
Late Pleistocene ◽  
Laptev Sea ◽  
Carbonate Formation ◽  
Siberian Arctic ◽  
The Laptev Sea

scholarly journals Modeling sub-sea permafrost in the East Siberian Arctic Shelf: The Laptev Sea region

2012 ◽  
Vol 117 (F3) ◽  
pp. n/a-n/a ◽  
Author(s):  
D. J. Nicolsky ◽  
V. E. Romanovsky ◽  
N. N. Romanovskii ◽  
A. L. Kholodov ◽  
N. E. Shakhova ◽  
...  
Keyword(s):  
Arctic Shelf ◽  
Laptev Sea ◽  
Siberian Arctic ◽  
The Laptev Sea

scholarly journals Source apportionment of methane escaping the subsea permafrost system in the outer Eurasian Arctic Shelf

2021 ◽  
Vol 118 (10) ◽  
pp. e2019672118
Author(s):  
Julia Steinbach ◽  
Henry Holmstrand ◽  
Kseniia Shcherbakova ◽  
Denis Kosmach ◽  
Volker Brüchert ◽  
...  
Keyword(s):  
Arctic Shelf ◽  
Laptev Sea ◽  
Methane Release ◽  
Horizontal Gradients ◽  
The Past ◽  
Gas Source ◽  
Stable Isotopic ◽  
Siberian Arctic ◽  
Subsea Permafrost ◽  
The Laptev Sea

The East Siberian Arctic Shelf holds large amounts of inundated carbon and methane (CH4). Holocene warming by overlying seawater, recently fortified by anthropogenic warming, has caused thawing of the underlying subsea permafrost. Despite extensive observations of elevated seawater CH4 in the past decades, relative contributions from different subsea compartments such as early diagenesis, subsea permafrost, methane hydrates, and underlying thermogenic/ free gas to these methane releases remain elusive. Dissolved methane concentrations observed in the Laptev Sea ranged from 3 to 1,500 nM (median 151 nM; oversaturation by ∼3,800%). Methane stable isotopic composition showed strong vertical and horizontal gradients with source signatures for two seepage areas of δ13C-CH4 = (−42.6 ± 0.5)/(−55.0 ± 0.5) ‰ and δD-CH4 = (−136.8 ± 8.0)/(−158.1 ± 5.5) ‰, suggesting a thermogenic/natural gas source. Increasingly enriched δ13C-CH4 and δD-CH4 at distance from the seeps indicated methane oxidation. The Δ14C-CH4 signal was strongly depleted (i.e., old) near the seeps (−993 ± 19/−1050 ± 89‰). Hence, all three isotope systems are consistent with methane release from an old, deep, and likely thermogenic pool to the outer Laptev Sea. This knowledge of what subsea sources are contributing to the observed methane release is a prerequisite to predictions on how these emissions will increase over coming decades and centuries.

scholarly journals The Formation of Authigenic Carbonates at a Methane Seep Site in the Northern Part of the Laptev Sea

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 948
Author(s):  
Alexey Ruban ◽  
Maxim Rudmin ◽  
Oleg Dudarev ◽  
Alexey Mazurov
Keyword(s):  
Seawater Temperature ◽  
Cold Seep ◽  
Anaerobic Oxidation Of Methane ◽  
Laptev Sea ◽  
Cold Seeps ◽  
Authigenic Carbonates ◽  
Oxidation Of Methane ◽  
Major Oxide ◽  
Mg Content ◽  
The Laptev Sea

Authigenic carbonates from cold seeps are unique archives for studying environmental conditions, including biogeochemical processes associated with methane-rich fluid migration through the sediment column. The aim of this research was to study major oxide, mineralogical, and stable isotopic compositions of cold-seep authigenic carbonates collected in the northern part of the Laptev Sea. These carbonates are represented by Mg-calcite with an Mg content of 2% to 8%. The δ13C values range from −27.5‰ to −28.2‰ Vienna Peedee belemnite (VPDB) and indicate that carbonates formed due to anaerobic oxidation of methane, most likely thermogenic in origin. The authigenic pyrite in Mg-calcite is evidence of sulfate reduction during carbonate precipitation. The δ18O values of carbonates vary from 3.5‰ to 3.8‰ VPDB. The calculated δ18Ofluid values show that pore water temperature for precipitated Mg-calcite was comparable to bottom seawater temperature. The presence of authigenic carbonate in the upper horizons of sediments suggests that the sulfate–methane transition zone is shallowly below the sediment–water interface.

scholarly journals A multiproxy-based reconstruction of the mid- to late Holocene paleoenvironment in the Laptev Sea off the Lena River Delta (Siberian Arctic)

2020 ◽  
Vol 540 ◽  
pp. 109502
Author(s):  
Оlga Rudenko ◽  
Еkaterina Taldenkova ◽  
Yaroslav Ovsepyan ◽  
Аnna Stepanova ◽  
Henning A. Bauch
Keyword(s):  
Late Holocene ◽  
River Delta ◽  
Laptev Sea ◽  
Lena River ◽  
Siberian Arctic ◽  
Lena River Delta ◽  
The Laptev Sea

scholarly journals Sonar Estimation of Methane Bubble Flux from Thawing Subsea Permafrost: A Case Study from the Laptev Sea Shelf

Geosciences ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 411
Author(s):  
Denis Chernykh ◽  
Vladimir Yusupov ◽  
Aleksandr Salomatin ◽  
Denis Kosmach ◽  
Natalia Shakhova ◽  
...  
Keyword(s):  
Laptev Sea ◽  
Sea Floor ◽  
Backscattering Cross Section ◽  
Siberian Arctic ◽  
Methane Fluxes ◽  
Methane Bubble ◽  
Acoustic Surveys ◽  
Subsea Permafrost ◽  
The Laptev Sea

Seeps found offshore in the East Siberian Arctic Shelf may mark zones of degrading subsea permafrost and related destabilization of gas hydrates. Sonar surveys provide an effective tool for mapping seabed methane fluxes and monitoring subsea Arctic permafrost seepage. The paper presents an overview of existing approaches to sonar estimation of methane bubble flux from the sea floor to the water column and a new method for quantifying CH4 ebullition. In the suggested method, the flux of methane bubbles is estimated from its response to insonification using the backscattering cross section. The method has demonstrated its efficiency in the case study of single- and multi-beam acoustic surveys of a large seep field on the Laptev Sea shelf.

scholarly journals The Mesozoic–Cenozoic tectonic evolution of the New Siberian Islands, NE Russia

2014 ◽  
Vol 152 (3) ◽  
pp. 480-491 ◽  
Author(s):  
CHRISTIAN BRANDES ◽  
KARSTEN PIEPJOHN ◽  
DIETER FRANKE ◽  
NIKOLAY SOBOLEV ◽  
CHRISTOPH GAEDICKE
Keyword(s):  
Tectonic Evolution ◽  
Structural Evolution ◽  
Arctic Shelf ◽  
Laptev Sea ◽  
Russian Arctic ◽  
Thrust Belt ◽  
Fold Belt ◽  
New Siberian Islands ◽  
Ne Russia ◽  
The Laptev Sea

AbstractOn the New Siberian Islands the rocks of the east Russian Arctic shelf are exposed and allow an assessment of the structural evolution of the region. Tectonic fabrics provide evidence of three palaeo-shortening directions (NE–SW, WNW–ESE and NNW–SSE to NNE–SSW) and one set of palaeo-extension directions revealed a NE–SW to NNE–SSW direction. The contractional deformation is most likely the expression of the Cretaceous formation of the South Anyui fold–thrust belt. The NE–SW shortening is the most prominent tectonic phase in the study area. The WNW–ESE and NNW–SSE to NNE–SSW-oriented palaeo-shortening directions are also most likely related to fold belt formation; the latter might also have resulted from a bend in the suture zone. The younger Cenozoic NE–SW to NNE–SSW extensional direction is interpreted as a consequence of rifting in the Laptev Sea.

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