Methane seeps on the outer shelf of the Laptev Sea: characteristic features, structural control, and benthic fauna

2020 ◽  
Vol 40 (4) ◽  
pp. 541-557 ◽  
Author(s):  
B. Baranov ◽  
S. Galkin ◽  
A. Vedenin ◽  
K. Dozorova ◽  
A. Gebruk ◽  
...  
Oceanology ◽  
2015 ◽  
Vol 55 (1) ◽  
pp. 68-81 ◽  
Author(s):  
I. I. Pipko ◽  
S. P. Pugach ◽  
I. P. Semiletov

2019 ◽  
Vol 486 (1) ◽  
pp. 571-574 ◽  
Author(s):  
B. V. Baranov ◽  
L. I. Lobkovsky ◽  
K. A. Dozorova ◽  
N. V. Tsukanov

2019 ◽  
Vol 486 (3) ◽  
pp. 354-358
Author(s):  
B. V. Baranov ◽  
L. I. Lobkovsky ◽  
K. A. Dozorova ◽  
N. V. Tsukanov

The paper presents data obtained during the 69th and 72nd expeditions of the research vessel Akademik Mstislav Keldysh (2017, 2018). A mechanism of methane discharge that explains the localization of the seep fields in a limited area of the outer shelf and suggesting a system of deep and surface faults is proposed. Along the deep faults, gas fluid is transferred to the upper strata of the sedimentary cover, where it is accumulated below the gas hydrate stability zone and the permafrost horizon. The surface faults of the outer shelf break this caprock, creating conduits for the gas to migrate to the surface and to jet-release into the water column.


2020 ◽  
Author(s):  
Anna Tikhonova ◽  
Sofia Merenkova

<p>We present the initial data on the distribution of benthic foraminifera (BF) on East Siberian Sea shelf. Previous researchers analyzed BF in the sediment cores from the continental slope and basin areas of the East Siberian Sea (Wollenburg et al., 2000; Mackensen et al, 2014; Barrientos et al, 2018) but not from central shelf. Last year we received boxcorer samples of bottom sediments from the shelf of the East Siberian Sea and the Laptev Sea during the 78th cruise of research vessel Akademik Mstislav Keldysh (September-October 2019). We examined the species composition of BF assemblages of Rose Bengal-stained surface samples from 2 stations in the East Siberian Sea and 7 stations in the Laptev Sea, and compared this data set with an existing data set along the East Siberian Sea and the Laptev Sea.</p><p>Recent studies (Shakhova et al, 2007, 2009, 2015; Nicolsky et al, 2009) state that the East Siberian Sea is one of the largest sources of methane emission into the atmosphere due to degradation of permafrost, ice complex retreat and decaying gas hydrates deposits. Perhaps this has an impact on the species composition of the BF assemblages and the morphological changes and defects of their shells, which we have identified. Samples from active methane seeps of the Laptev Sea have been studied to identify the relationship between methane emission and the reaction of benthic foraminifera. This data have been compared with “background” (i.e. non-venting, without any methane seeps activity) stations of the Laptev Sea and the East Siberian Sea.</p><p>The identified features require further detailed study.</p>


2014 ◽  
Vol 44 (1) ◽  
pp. 202-219 ◽  
Author(s):  
Markus A. Janout ◽  
Yueng-Djern Lenn

Abstract The Arctic continental shelf seas hold a globally significant source of freshwater that impacts Arctic Ocean stratification, circulation, and climate. This freshwater can be injected below the surface mixed layer by intense turbulent kinetic energy dissipation events, as resolved by Laptev Sea microstructure observations. The tides provide a major source of energy that can be dissipated and hence drive diapycnal mixing in the Laptev Sea. Multiyear ADCP mooring records from locations across the shelf reveal that semidiurnal tides are dominated by the M2 and S2 constituents, with the largest amplitudes on the outer shelf. Throughout most of the shelf, tides are clockwise polarized and sheared by stratification, as characteristic near the M2 critical latitude. Interannual variations of the tidal and shear structures on the inner shelf are mainly determined by the stratification-setting Lena River freshwater plume. In all locations, M2 tides are enhanced under sea ice, and therefore changes in the seasonal ice cover may lead to changes in tides and water column structure. The main conclusions of this study are that (i) tides play a comparatively greater role year-round on the outer shelf relative to the inner shelf; (ii) a sea ice reduction will overall decrease the predictability of the currents, especially on the inner shelf; and (iii) the freshwater distribution directly impacts diapycnal mixing by setting the vertical tidal structure. These combined effects imply that future sea ice loss will increase the variability and vertical mixing of freshwater, particularly on the inner shelf, where the Lena River first enters the Laptev Sea.


Sign in / Sign up

Export Citation Format

Share Document