History of Holocene Sedimentation in the Southern Kara Sea

Abstract-The analysis of the lithology, grain size distribution, clay minerals, and geochemistry of Upper Pleistocene sediments from the submarine Shirshov Ridge (Bering Sea) showed that the main source area was the Yukon-Tanana terrane of Central Alaska. The sedimentary materials were transported by the Yukon River through Beringia up to the shelf break, where they were entrained by a strong northwestward flowing sea current. The lithological data revealed several pulses of ice rafted debris deposition, roughly synchronous with Heinrich events, and periods of weaker bottom current intensity. Based on the geochemical results, we distinguished intervals of an increase in paleoproductivity and extension of the oxygen minimum zone. The results suggest that there were three stages of deposition driven by glacioeustatic sea level fluctuations and glacial cycles in Alaska.

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“…This is a well known phenomenon, which was described, for instance, in our previous study in the Yenisei Gulf of the Kara Sea [28].…”

Section: Resultssupporting

confidence: 56%

Late pleistocene sedimentation history of the Shirshov Ridge, Bering Sea

et al. 2013

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“…Pre-Weichselian deposits consist mostly of clays overlain by interbeds of sands, Journal of Geophysical Research: Earth Surface 10.1002/2015JF003467 silts, and clays of Middle Weichselian to Holocene age (marine oxygen isotope stage (MIS)4-MIS1) [Melnikov and Spesivtsev, 1995]. The uppermost Holocene sediments consist of mud with low sand content and scarce ice-rafted debris [Levitan et al, 2004;Stein et al, 2004]. Holocene sedimentation is facilitated by the vigorous sediment deposition from rivers and extensive coastal erosion.…”

Section: Tectonic Framework Seafloor Morphology and Lithology Of Bottom Sedimentsmentioning

confidence: 99%

Methane release from pingo‐like features across the South Kara Sea shelf, an area of thawing offshore permafrost

et al. 2015

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The Holocene marine transgression starting at~19 ka flooded the Arctic shelves driving extensive thawing of terrestrial permafrost. It thereby promoted methanogenesis within sediments, the dissociation of gas hydrates, and the release of formerly trapped gas, with the accumulation in pressure of released methane eventually triggering blowouts through weakened zones in the overlying and thinned permafrost. Here we present a range of geophysical and chemical scenarios for the formation of pingo-like formations (PLFs) leading to potential blowouts. Specifically, we report on methane anomalies from the South Kara Sea shelf focusing on two PLFs imaged from high-resolution seismic records. A variety of geochemical methods are applied to study concentrations and types of gas, its character, and genesis. PLF 1 demonstrates ubiquitously low-methane concentrations (14.2-55.3 ppm) that are likely due to partly unfrozen sediments with an ice-saturated internal core reaching close to the seafloor. In contrast, PLF 2 reveals anomalously high-methane concentrations of >120,000 ppm where frozen sediments are completely absent. The methane in all recovered samples is of microbial and not of thermogenic origin from deep hydrocarbon sources. However, the relatively low organic matter content (0.52-1.69%) of seafloor sediments restricts extensive in situ methane production. As a consequence, we hypothesize that the high-methane concentrations at PLF 2 are due to microbial methane production and migration from a deeper source.

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“… Position of 14 C ages in sediment cores PS2718‐6, PS‐2719‐1 and PS2792‐5 (see Stein et al. 2001 and Levitan et al. 2000 for the age data).…”

Section: Age Controlmentioning

confidence: 99%

“…10 and 12 Kya ( Fig. 10; Stein et al 2001;Levitan et al 2000). Extrapolation of sedimentation rates of ca.…”

Section: Age Controlmentioning

confidence: 99%

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The eastern extent of the Barents–Kara ice sheet during the Last Glacial Maximum based on seismic-reflection data from the eastern Kara Sea

Polyak

Niessen

Gataullin³

et al. 2008

Polar Research

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We present sub‐bottom profiling (sparker and Parasound) results from the eastern Kara Sea, on the Eurasian Arctic margin, which enable the identification of the Last Glacial Maximum (LGM) ice extent. The analysed profiles show that glacigenic diamicton is ubiquitous at the seafloor, east of about 95°E and 78°N. The eastern margin of this diamicton is expressed in a conspicuous morainic ridge at the entrance to the Vilkitsky Strait, and to the south the diamicton projection aligns with the LGM limit mapped at the north‐western Taymyr. The bottom of the Voronin Trough further north is also covered with diamicton and has numerous erosional bedforms, indicating a streamlined flow of grounded ice along the trough. Accurate dating of the diamicton is not attainable, but the correlation of pre‐diamict sediments to well‐dated sections in the Laptev Sea, and available 14C ages from sediments on top of the diamicton, indicate its LGM age. These results support the palaeogeographic reconstruction that assumes the extension of the LGM Barents–Kara ice sheet as far east as Taymyr. This configuration implies that LGM ice blocked the drainage of the Ob and Yenisey rivers on the Kara shelf. This inference is consistent with the presence of large (>100 km wide) lenses of basin infill adjacent to the southern margin of the diamicton. However, the limited distribution of the eastern Kara ice lobe, not extending on Severnaya Zemlya, suggests that the ice was fairly thin and short‐lived: insufficient for the accumulation of the gigantic proglacial lakes that occurred during earlier glaciations.

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History of Holocene Sedimentation in the Southern Kara Sea

Cited by 12 publications

References 15 publications

Late pleistocene sedimentation history of the Shirshov Ridge, Bering Sea

Late pleistocene sedimentation history of the Shirshov Ridge, Bering Sea

Methane release from pingo‐like features across the South Kara Sea shelf, an area of thawing offshore permafrost

The eastern extent of the Barents–Kara ice sheet during the Last Glacial Maximum based on seismic-reflection data from the eastern Kara Sea

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