Holocene History of the Laptev Sea Continental Shelf

Holmes, Mark L.; Creager, Joe S.

doi:10.1007/978-3-642-87411-6_9

Cited by 50 publications

(33 citation statements)

References 15 publications

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“…We support the idea about the glacioeustatic nature of transgression-regression cycles in the region, indicated by data on sea-level fluctuations in Eastern Siberian and Bering seas (Holmes and Creager 1974;Creager and McManus 1967;Hopkins 1976;Ivanov 1982;Veinbergs 1991;Selivanov 1996).…”

Section: A Brief Description Of East Siberia Arctic Shelf Environmentsupporting

confidence: 87%

Offshore permafrost and gas hydrate stability zone on the shelf of East Siberian Seas

et al. 2005

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Dynamics of the submarine permafrost regime, including distribution, thickness, and temporal evolution, was modeled for the Laptev and East Siberian Sea shelf zones. This work included simulation of the permafrost-related gas hydrate stability zone (GHSZ). Simulations were compared with field observations. Model sensitivity runs were performed using different boundary conditions, including a variety of geological conditions as well as two distinct geothermal heat flows (45 and 70 mW/m 2 ). The heat flows used are typical for the coastal lowlands of the Laptev Sea and East Siberian Sea. Use of two different geological deposits, that is, unconsolidated Cainozoic strata and solid bedrock, resulted in the significantly different magnitudes of permafrost thickness, a result of their different physical and thermal properties. Both parameters, the thickness of the submarine permafrost on the shelf and the related development of the GHSZ, were simulated for the last four glacial-eustatic cycles (400,000 years). The results show that the most recently formed permafrost is continuous to the 60-m isobath; at the greater depths of the outer part of the shelf it changes to discontinuous and ''patchy'' permafrost. However, model results suggest that the entire Arctic shelf is underlain by relic permafrost in a state stable enough for gas hydrates. Permafrost, as well as the GHSZ, is currently storing probable significant greenhouse gas sources, especially methane that has formed by the decomposition of gas hydrates at greater depth. During climate cooling and associated marine regression, permafrost aggradation takes place due to the low temperatures and the direct exposure of the shelf to the atmosphere. Permafrost degradation takes place during climate warming and marine transgression. However, the temperature of transgressing seawater in contact with the former terrestrial permafrost landscape remains below zero, ranging from À0.5 to À1.8°C, meaning permafrost degradation does not immediately occur. The submerged permafrost degrades slowly, undergoing a transformation in form from ice bonded terrestrial permafrost to ice bearing submarine permafrost that does not possess a temperature gradient. Finally the thickness of ice bearing permafrost decreases from its lower boundary due to the geothermal heat flow. The modeling indicated several other features. There exists a time lag between extreme states in climatic forcing and associated extreme states of permafrost thickness. For example, permafrost continued to degrade for up to 10,000 years following a temperature decline had begun after a climate optimum. Another result showed that the dynamic of permafrost thickness and the variation of the GHSZ are similar but not identical. For example, it can be shown that in recent time permafrost degradation has taken place at the outer part of the shelf whereas the GHSZ is stable or even thickening.

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Section: A Brief Description Of East Siberia Arctic Shelf Environmentsupporting

confidence: 87%

Offshore permafrost and gas hydrate stability zone on the shelf of East Siberian Seas

et al. 2005

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“…For the Early to Middle Weichselian, the sea level curve of Chappell et al (1996) can be applied (Romanovskii et al, 1999;Hubberten and Romanovskii, in press). The continental shelf is very flat with a break occurring at 50-60 m water depth, and Table 1. varies in width from 300 to over 500 km (Holmes and Creager, 1974). This implies that during the deposition of the sandy sediments of the third terrace and the IC at 60 and 30 ka BP, sea level was about 60 m lower than at present (Hubberten and Romanovskii, in press).…”

Section: Distribution Of 14 C-and Ir-osl-dated Sediments and Their LImentioning

confidence: 99%

Late Quaternary sedimentation history of the Lena Delta

Schwamborn

Rachold

Grigoriev

2002

Quaternary International

165

176

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Core and outcrop analysis from Lena mouth deposits have been used to reconstruct the Late Quaternary sedimentation history of the Lena Delta. Sediment properties (heavy mineral composition, grain size characteristics, organic carbon content) and age determinations ( 14 C AMS and IR-OSL) are applied to discriminate the main sedimentary units of the three major geomorphic terraces, which form the delta. The development of the terraces is controlled by complex interactions among the following four factors: (1) Channel migration. According to the distribution of 14 C and IR-OSL age determinations of Lena mouth sediments, the major river runoff direction shifted from the west during marine isotope stages 5-3 (third terrace deposits) towards the northwest during marine isotope stage 2 and transition to stage 1 (second terrace), to the northeast and east during the Holocene (first terrace deposits). (2) Eustasy. Sea level rise from Last Glacial lowstand to the modern sea level position, reached at 6-5 ka BP, resulted in back-filling and flooding of the palaeovalleys. (3) Neotectonics. The extension of the Arctic Mid-Ocean Ridge into the Laptev Sea shelf acted as a halfgraben, showing dilatation movements with different subsidence rates. From the continent side, differential neotectonics with uplift and transpression in the Siberian coast ridges are active. Both likely have influenced river behavior by providing sites for preservation, with uplift, in particular, allowing accumulation of deposits in the second terrace in the western sector. The actual delta setting comprises only the eastern sector of the Lena Delta. (4) Peat formation. Polygenetic formation of icerich peaty sand (''Ice Complex'') was most extensive (7-11 m in thickness) in the southern part of the delta area between 43 and 14 ka BP (third terrace deposits). In recent times, alluvial peat (5-6 m in thickness) is accumulated on top of the deltaic sequences in the eastern sector (first terrace). r

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“…The permafrost was formed subaerially during cold periods in the Quaternary when relative sea levels were low. Sea-level fluctuations for the Laptev Sea during Quaternary times were determined by Holmes and Creager (1974) based on radiocarbon dating of sediment cores. Their data indicated that the sea level was 50 to 55 m lower about 15,000 years b.p.…”

Section: Marine Permafrostmentioning

confidence: 99%

“…With an area of 460,000 sq. km (Holmes and Creager, 1974) and an average water depth of 53m (Timokhov, 1994), the Laptev Sea is one of world's largest and shallowest shelf areas. The tectonic structure of the Laptev Sea shelf is linked to the opening and development of the oceanic Eurasia Basin (Fig.…”

Section: Introductionmentioning

confidence: 99%