Fluid migrations at the Krasny Yar methane seep of Lake Baikal according to geochemical data

We examined amphipods collected from aboard the deepwater manned submersibles “Mir-1” and “Mir-2” at oil and methane seeps near Cape Gorevoy Utes (Central Baikal). Most of the 23 taxa registered inhabit the entire Lake Baikal within a wide depth range. Two species of the genus Echiuropus are probably new. Leptostenus leptocerus (Dybowsky, 1874), that, until now, was regarded as a rare species, is likely to be an indicator for methane and oil discharge areas. Additional data on the morphology of this species were obtained; cuticular sensory (lateral line organs) and nonsensory microstructures were examined by scanning electron microscopy. The density of nectobenthic amphipods was 5-6 times higher on bitumen mounds than that at neighbouring sites with flat bottom. Maximum density of benthic amphipods was recorded on bacterial mats. No amphipods were observed at the bottom with large oil patches. High density of amphipods at the oil-methane seep is attributed to highly structured habitats and food abundance.

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Differentiation of communities of macroinvertebrates and cottoid fish associated with methane seeps of different bottom landscapes of Lake Baikal

Proceedings of the Zoological Institute RAS ◽

10.31610/trudyzin/2021.325.4.469 ◽

2021 ◽

Vol 325 (4) ◽

pp. 469-484

Author(s):

V.G. Sideleva ◽

T.Ya. Sitnikova

Keyword(s):

Lake Baikal ◽

Deep Water ◽

Gas Hydrates ◽

Microbial Mats ◽

Methane Seep ◽

Methane Seeps ◽

Saint Petersburg ◽

Transitional State ◽

Cottoid Fishes ◽

Cottoid Fish

The paper presents the results of the study of communities of macroinvertebrates and cottoid fish inhabiting methane seeps of Lake Baikal. For the analysis, we used video surveillance and collection of animals carried out with the help of "Mir" deep-water submersible, as well as NIOZ-type box-corer samplers from the board of a research vessel. Posolskaya Bank and Saint Petersburg methane seeps are located in different basins (southern and middle) and at different depths (300–500 m and ~ 1400 m), characterized by the different underwater landscapes (slope of underwater upland and hills formed by gas hydrates), by the structure of gas hydrates and their depth location in sediments, as well as the composition of microbial mats and communities of microorganisms of bottom sediments. Both seeps are characterized by bubble discharge of methane gas and the formation of highly productive communities of large invertebrates and cottoid fish on seep habitats. Seep animal communities consisted of species-depleted invertebrates and fish of the surrounding deep-water benthal of the Lake. We showed the similarities and differences in the composition of the faunas of two seeps, as well as the quantitative characteristics of taxonomic groups of macroinvertebrates and cottoid fishes. Obligate species have not been revealed on the methane seep Posolskaya Bank. For the methane seep Saint Petersburg, the gastropod species Kobeltocochlea tamarae Sitnikova, Teterina et Maximova, 2021 (Caenogastropoda: Benedictiidae) was designated as an obligate species; among bottom cottoid fishes, Neocottus werestschagini (Taliev, 1953) (Cottoidei: Abyssocottidae) had possible a transitional state to obligate. We presented the data on the assimilation by seep animals of mixed photo- and chemosynthetic food with different proportions of methane-derived carbon. A hypothesis has been substantiated that deep-water seep areas could serve as refugium for the preservation of endemic fauna during the Pliocene-Pleistocene glaciations of Lake Baikal.

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Integrated analysis of geophysical and geochemical data from cold fluid seepage system along the Gydratny Fault (Lake Baikal)

10.5194/egusphere-egu2020-20934 ◽

2020 ◽

Author(s):

Olesya Vidischeva ◽

Marina Solovyeva ◽

Evgeniya Egoshina ◽

Yana Vasilevskaya ◽

Elena Poludetkina ◽

...

Keyword(s):

Isotopic Composition ◽

Lake Baikal ◽

Carbon Isotopic Composition ◽

Fault System ◽

Geochemical Data ◽

Integrated Analysis ◽

Fluid Migration ◽

Carbon Isotopic ◽

Lake Bottom ◽

Methane Concentrations

Lake Baikal is a part of large intracontinental rift zone. Baikal sedimentary infill is more than 7 km thick and was developed under predominantly extensional tectonics. Large number of faults of different geometry is imaged by several seismic surveys carried out in the region. The fault systems serve as fluid discharge pathways from deep sources to surface. A number of active seepage structures were mapped and studied during the Class@Baikal expeditions along the major fault system of the Central Baikal basin, which extends in SW-NE direction over 40 km and was named recently as the Gydratny Fault. Irregular distribution of these seeps, differences in their morphology and activity rate imply a variable permeability of the fault and different characteristics of migration pathways along its segments.High-resolution seismic sections were acquired across the Gydratny Fault during the Class@Baikal cruises. The survey was followed by extensive bottom sediments and gases sampling. Hydrocarbon gases and isotopic characteristics as well as sediment pore water composition were analysed. Methane was detected in sediments along the whole fault extend in concentrations of more than 100 ml/l, exceeding background values (<15 ml/l), suggesting that the fault plane acts as regional fluid migration path. The highest methane content (>275 ml/l) and the presence of its homologues were observed at several local sites situated along the fault and associated with mud volcanoes and gas hydrate bearing seeps. The carbon isotopic composition varies from -72 to -57&#8240; VPDB for methane and from -21 to -31 &#8240; VPDB for ethane, suggesting that these are thermogenic gases that migrate from deep layers of sedimentary infill of the basin.Seismic data show well-established segmented nature of the Gydratny Fault system, which is believed to be a reason for observed variations of fluid discharge rates. Integrated analysis of the collected geophysical and geochemical data allowed evaluating contributions of different structural elements of the Gydratny Fault to fluid migration pattern in the area. NE segment of the fault system is a well expressed normal fault propagating to the lake bottom which is associated with higher methane concentrations (150-200 ml/l), elevated methane homologues content of up to 40 ml/l and heavier carbon isotopic composition in gas samples. The SW segments is either faintly expressed in the bottom relief or does not reach the surface at all. The methane concentrations in sediment samples collected from the segment are 100-150 ml/l and its carbon isotopic composition is normally lighter. We suggest that deeper parts of the SW fault segment are still highly conductive and concentrated hydrocarbon fluids migrate from the source upwards but some near-surface dispersal of migrated fluids occurs at places where the fault does not reach the lake bottom. The Gydratny master fault is accompanied by numerous subsidiary faults developed within hanging wall while footwall is less faulted. The associated faults are believed to enhance the main fluid migration system and this interpretation is supported by observations of normally higher methane concentrations in bottom sediments of the hanging block.This study was funded by RFBR Grant &#8470; 18-35-00363.

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The importance of geochemical data for geodynamic reconstruction: formation of the Olkhon metamorphic complex, Lake Baikal, Russia

Lithos ◽

10.1016/s0024-4937(98)00010-3 ◽

1998 ◽

Vol 43 (3) ◽

pp. 135-150 ◽

Cited By ~ 12

Author(s):

V Makrygina

Keyword(s):

Lake Baikal ◽

Geochemical Data ◽

Metamorphic Complex

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A method to differentiate hydrocarbon source (oil vs methane) in authigenic carbonate rock from seeps

10.5194/egusphere-egu2020-1038 ◽

2020 ◽

Author(s):

Yuedong Sun ◽

Shanggui Gong ◽

Niu Li ◽

Jörn Peckmann ◽

Meng Jin ◽

...

Keyword(s):

Carbon Sources ◽

Sediment Surface ◽

Geochemical Data ◽

Methane Seep ◽

Geological Time ◽

Significant Control ◽

Oil Seeps ◽

Oil Seepage ◽

Oil Seep ◽

Late Diagenesis

AbstractNumerous marine hydrocarbon seeps have been discovered in the past three decades, the majority of which are dominated by methane-rich fluids. However, an increasing number of modern oil seeps and a few ancient oil-seep deposits have been recognized in recent years. Oil seepage exerts significant control on the composition of the seep-dwelling fauna and may have impacted the marine carbon cycle through geological time to a greater extent than previously recognized. Yet, distinguishing oil-seep from methane-seep deposits is difficult in cases where &#948;13Ccarb values are higher than approximately -30&#8240; due to mixing of different carbon sources. Here, we present a comparative study of authigenic carbonates from oil-dominated (site GC232) and methane-dominated (site GC852) seep environments of the northern Gulf of Mexico, aiming to determine the geochemical characteristics of the two types of seep carbonates. We analyzed (1) Major and trace element compositions of carbonates, (2) total organic carbon (TOC), total nitrogen (TN) and carbon isotope (&#948;13CTOC) of residue after decalcification, (3) sulfur isotope signatures of chromium reducible sulfur (CRS, &#948;34SCRS) and residue after CRS extraction (&#948;34STOS ), as well as (4) sulfur contents (TOS) of residue after CRS extraction. Carbonates from the studied oil seep are dominated by aragonite and exhibit lower &#948;34SCRS values, suggesting carbonate precipitation close to the sediment surface. In addition, oil-seep carbonates are characterized by higher TOC and TOS contents and higher TOC/TN ratios, as well as less negative &#948;13CTOC values compared to methane-seep carbonates, probably reflecting a contribution of residual crude oil enclosed in oil-seep carbonates. Very low &#948;13CTOC values (as low as &#8722;68.7&#8240;, VPDB) and low TOC/TN ratios of methane-seep carbonates indicate that the enclosed organic matter is derived mainly from the biomass of methanotrophic biota. This study presents new geochemical data that will allow the discrimination of oil-seep from methane-seep deposits. Although some of the geochemical patterns are likely to be affected by late diagenesis, if applied with caution, such patterns can be used to discern the two end-member types of seepage &#8211; oil seeps and methane seeps &#8211; in the geological record.

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Fauna of Cottoid fish (Cottoidei) in the area of methane seep in the abyssal of Lake Baikal

Doklady Biological Sciences ◽

10.1134/s0012496614060088 ◽

2014 ◽

Vol 459 (1) ◽

pp. 351-353 ◽

Cited By ~ 2

Author(s):

V. G. Sideleva ◽

V. A. Fialkov

Keyword(s):

Lake Baikal ◽

Methane Seep ◽

Cottoid Fish

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Effect of Methanol and Mineral Nitrogen Compounds on the Composition of Methanotrophic Enrichments from the Sediments of a Lake Baikal Methane Seep

Microbiology ◽

10.1134/s0026261721040123 ◽

2021 ◽

Vol 90 (4) ◽

pp. 443-454

Author(s):

O. V. Shubenkova ◽

A. S. Zakharenko ◽

Yu. P. Galach’yants ◽

G. V. Kalmychkov ◽

V. G. Ivanov ◽

...

Keyword(s):

Lake Baikal ◽

Mineral Nitrogen ◽

Nitrogen Compounds ◽

Methane Seep

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Trophic relationships between macroinvertebrates and fish in St. Petersburg methane seep community in abyssal zone of Lake Baikal

Contemporary Problems of Ecology ◽

10.1134/s1995425517020123 ◽

2017 ◽

Vol 10 (2) ◽

pp. 147-156 ◽

Cited By ~ 1

Author(s):

T. Ya. Sitnikova ◽

I. V. Mekhanikova ◽

V. G. Sideleva ◽

S. I. Kiyashko ◽

T. V. Naumova ◽

...

Keyword(s):

Lake Baikal ◽

Trophic Relationships ◽

Methane Seep ◽

Abyssal Zone

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