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Bolshoy Lyakhovsky Island ((ロシア語:Большой Ляховский)), or Great Lyakhovsky, is the largest of the Lyakhovsky Islands belonging to the New Siberian Islands archipelago between the Laptev Sea and the East Siberian Sea in northern Russia. It has an area of 4,600 km², and a maximum altitude of 270 m (Emy Tas).〔anonymous, 1911, (New Siberia Archipelago )〕 The peninsula projecting towards the west of the island is the Kigilyakh Peninsula (Poluostrov Kigilyakh). Off Bolshoy Lyakhovsky Island's southwestern cape lies a small islet called Ostrov Khopto-Terer. The Lyakhovsky Islands are named in honour of Ivan Lyakhov, who explored them in 1773. ==Geology== Bolshoy Lyakhovsky Island consists of highly folded and faulted Precambrian metamorphic rocks and turbidites; Mesozoic turbidites and igneous rocks; and Cenozoic sediments. Exposed in southeastern part of this island, the older Precambrian. Early Proterozoic, metamorphic rocks consist of schists and amphibolites. Small exposures of Late Proterozoic schistose, quartzose sandstones and phyllitic, sericite-quartz schist (turbidites) also occur in the southeastern part of Bolshoy Lyakhovsky Island. The bulk of this island consists of Late Jurassic to Early Cretaceous turbidites composed of interbedded fine-grained sandstones, thinly bedded siltstones, and argillites. The Precambrian and Late Jurassic to Early Cretaceous rocks are intruded by Late Cretaceous granites and granodiorites.〔Kos'ko, M.K., B.G. Lopatin, and V.G. Ganelin, 1990, ''Major geological features of the islands of the East Siberian and Chukchi Seas and the Northern Coast of Chukotka.'' Marine Geology. vol. 93, pp. 349–367.〕〔Fujita, K., and D.B. Cook, 1990, ''The Arctic continental margin of eastern Siberia'', in A. Grantz, L. Johnson, and J. F. Sweeney, eds., pp. 289–304, The Arctic Ocean Region. Geology of North America, vol L, Geological Society of America, Boulder, Colorado.〕〔Kyz'michev, A.B., A.V. Soloviev, V.E. Gonikberg, M.N. Shapiro, and O.V. Zamzhitskii, 2006, ''Mesozoic Syncollision Siliciclastic Sediments of the Bol'shoi Lyakhov Island (New Siberian Islands).'' Stratigraphy and Geological Correlation. vol. 14, no. 1, pp. 30–48.〕 A blanket of unconsolidated Cenozoic sediments blankets most of Bolshoy Lyakhovsky Island. These sediments include Paleocene to Eocene colluvial, alluvial, and deltaic gravels, sands, clays, and coals and Oligocene to Miocene alluvial, lacustrine, deltaic, and nearshore marine sands and clays that contain beds and lenses of gravel. Overlying these sediments are Pliocene to Pleistocene colluvial, alluvial, and nearshore marine sands, silts, and clays that contain occasional gravel layers. The nearshore marine sediments contain the shells of marine mollusks and pieces of lignitized wood. Thick permafrost characterized by massive ice wedges has developed in these sediments. Contrary to the interpretations of Baron von Toll〔von Toll, Baron E., 1895, Wissenschaftliche Resultate der Von der Kaiserlichen Akademie der Wissenschaften sur Erforschung des Janalandes und der Neusibirischen Inseln in den Jahren 1885 und 1886 Ausgesandten expedition. (Results of the Imperial Academy of Sciences of the Investigation of Janaland and the New Siberian Islands from the Expeditions Launched in 1885 and 1886 ) Abtheilung III: Die fossilen Eislager und ihre Beziehungen su den Mammuthleichen. Memoires de L'Academie imperials des Sciences de St. Petersbouro, VII Serie, Tome XLII, No. 13, Commissionnaires de I'Academie Imperiale des sciences, St. Peterabourg, Russia.〕 and earlier geologists, glacial tills and related sediments are completely absent within Bolshoy Lyakhovsky Island.〔〔Kos'ko, M.K., and G.V. Trufanov, 2002, (''Middle Cretaceous to Eopleistocene Sequences on the New Siberian Islands: an approach to interpret offshore seismic''. ) Marine and Petroleum Geology. vol. 19, no. 7, pp. 901–919.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Bolshoy Lyakhovsky Island」の詳細全文を読む スポンサード リンク
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