Flat-topped mounds in western Ross Sea: Carbonate mounds or subglacial volcanic features?

Lawver, Lawrence A.; Lee, Jaejin; Kim, Y.; Davey, F. J.

doi:10.1130/ges00766.1

Cited by 14 publications

(11 citation statements)

References 25 publications

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“…However, environments where a significant fraction of methane is produced appear to only harbor small fraction of methanogen populations ( Inagaki et al, 2006 ; Gies et al, 2014 ; Lever, 2016 ; Carr et al, 2018 ). Additionally, seismic evidence of gas hydrates and free gas have been reported in the Victoria Land Basin and pockmarks off Franklin Island in the Ross Sea, indicating the potential of subsurface gas release in the study area ( Geletti and Busetti, 2011 ; Lawver et al, 2012 ). Therefore, the presence of microbial groups frequently found in gas hydrates, organic-rich sediments, and other methanogenic environments and seismic surveys seem to suggest the possibility of biogenic methane production in the sediments of the western Ross Sea.…”

Section: Discussionmentioning

confidence: 86%

Genomic Insight Into the Predominance of Candidate Phylum Atribacteria JS1 Lineage in Marine Sediments

et al. 2018

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Candidate phylum Atribacteria JS1 lineage is one of the predominant bacterial groups in anoxic subseafloor sediments, especially in organic-rich or gas hydrate-containing sediments. However, due to the lack of axenic culture representatives, metabolic potential and biogeochemical roles of this phylum have remained elusive. Here, we examined the microbial communities of marine sediments of the Ross Sea, Antarctica, and found candidate phylum Atribacteria JS1 lineage was the most abundant candidate phylum accounting for 9.8–40.8% of the bacterial communities with a single dominant operational taxonomic unit (OTU). To elucidate the metabolic potential and ecological function of this species, we applied a single-cell genomic approach and obtained 18 single-cell amplified genomes presumably from a single species that was consistent with the dominant OTU throughout the sediments. The composite genome constructed by co-assembly showed the highest genome completeness among available Atribacteria JS1 genomes. Metabolic reconstruction suggested fermentative potential using various substrates and syntrophic acetate oxidation coupled with hydrogen or formate scavenging methanogens. This metabolic potential supports the predominance of Atribacteria JS1 in anoxic environments expanding our knowledge of the ecological function of this uncultivated group.

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Section: Discussionmentioning

confidence: 86%

Genomic Insight Into the Predominance of Candidate Phylum Atribacteria JS1 Lineage in Marine Sediments

et al. 2018

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“…4), similar to terminal berms of icebergs plough marks (e.g. Lewis et al, 2016). Sub-bottom profiler data across the ridges reveal their formation in an acoustically transparent sediment layer on top of a strong, continuous sub-bottom reflector (insets of Fig.…”

Section: Squeezed and Smeared Ridges Formed By Grounded Tabular Icebementioning

confidence: 63%

“…If an iceberg encounters seafloor substrate where drag associated with ploughing increases to match the force pushing the iceberg into the seabed, the movement of the iceberg slows down drastically and eventually stops, with the iceberg keel producing a terminal berm that consists of the pushed substrate at its front (e.g. Lewis et al, 2016). A statistical investigation from the eastern Amundsen Sea embayment shelf shows that most of the observed iceberg plough marks there have widths of 40-300 m and incision depths of less than 20 m (Wise et al, 2017), with iceberg plough mark berm heights typically being about 50 % of the incision depths.…”

Section: Iceberg Ramps (Class H)mentioning

confidence: 99%

Past ice sheet–seabed interactions in the northeastern Weddell Sea embayment, Antarctica

Arndt¹,

Larter²,

Hillenbrand³

et al. 2020

The Cryosphere

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Abstract. The Antarctic ice sheet extent in the Weddell Sea embayment (WSE) during the Last Glacial Maximum (LGM; ca. 19–25 calibrated kiloyears before present, ka cal BP) and its subsequent retreat from the shelf are poorly constrained, with two conflicting scenarios being discussed. Today, the modern Brunt Ice Shelf, the last remaining ice shelf in the northeastern WSE, is only pinned at a single location and recent crevasse development may lead to its rapid disintegration in the near future. We investigated the seafloor morphology on the northeastern WSE shelf and discuss its implications, in combination with marine geological records, to create reconstructions of the past behaviour of this sector of the East Antarctic Ice Sheet (EAIS), including ice–seafloor interactions. Our data show that an ice stream flowed through Stancomb-Wills Trough and acted as the main conduit for EAIS drainage during the LGM in this sector. Post-LGM ice stream retreat occurred stepwise, with at least three documented grounding-line still-stands, and the trough had become free of grounded ice by ∼10.5 ka cal BP. In contrast, slow-flowing ice once covered the shelf in Brunt Basin and extended westwards toward McDonald Bank. During a later time period, only floating ice was present within Brunt Basin, but large “ice slabs” enclosed within the ice shelf occasionally ran aground at the eastern side of McDonald Bank, forming 10 unusual ramp-shaped seabed features. These ramps are the result of temporary ice shelf grounding events buttressing the ice further upstream. To the west of this area, Halley Trough very likely was free of grounded ice during the LGM, representing a potential refuge for benthic shelf fauna at this time.

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“…Moreover, [65] supposed the presence of a BSR, an indirect indication of the presence of gas hydrate, on a seismic line, located in the Victoria Land Basin. Moreover, in the same part of the Ross Sea, an extensive field of pockmarks at 450-500 m depth and unusual flat-topped seafloor mounds was identified on a detailed multibeam dataset [66,67]. One hypothesis discussed by the authors is that these features may be carbonate banks because of their proximity to the inferred subsurface gas hydrate, although their preferred interpretation is that the features are of volcanic origin.…”

Section: The Ross Seamentioning

confidence: 99%

Gas Hydrates in Antarctica

Giustiniani¹,

Tinivella²

2021

Glaciers and the Polar Environment

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Few potential distributing areas of gas hydrates have been recognized in literature in Antarctica: the South Shetland continental margin, the Weddell Sea, the Ross Sea continental margin and the Wilkes Land continental margin. The most studied part of Antarctica from gas hydrate point of view is the South Shetland margin, where an important gas hydrate reservoir was well studied with the main purpose to determine the relationship between hydrate stability and environment effects, including climate change. In fact, the climate signals are particularly amplified in transition zones such as the peri-Antarctic regions, suggesting that the monitoring of hydrate system is desirable in order to detect potential hydrate dissociation as predicted by recent modeling offshore Antarctic Peninsula. The main seismic indicator of the gas hydrate presence, the bottom simulating reflector, was recorded in few parts of Antarctica, but in some cases it was associated to opal A/CT transition. The other areas need further studies and measurements in order to confirm or refuse the gas hydrate presence.

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Flat-topped mounds in western Ross Sea: Carbonate mounds or subglacial volcanic features?

Cited by 14 publications

References 25 publications

Genomic Insight Into the Predominance of Candidate Phylum Atribacteria JS1 Lineage in Marine Sediments

Genomic Insight Into the Predominance of Candidate Phylum Atribacteria JS1 Lineage in Marine Sediments

Past ice sheet–seabed interactions in the northeastern Weddell Sea embayment, Antarctica

Gas Hydrates in Antarctica

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