--> Abstract: Geology of New Siberian Islands – A Key to Understanding the Structural History of the Laptev and East Siberian Seas, by Mikhail Kosko; #90177 (2013)

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Geology of New Siberian Islands – A Key to Understanding the Structural History of the Laptev and East Siberian Seas

Mikhail Kosko

Continental crust of the New Siberian Islands was emplaced close to the Precambrian/Paleozoic boundary. In Early and Middle Paleozoic time the area was occupied by shallow water sea basins. Island arc environment existed in the De Long Islands. In Middle and Late Devonian high energy geodynamics caused variable sedimentary settings, disconformities, coexisting flysh and carbonate shelf facies. Low energy geodynamics indicated by shallow water sea basins persisted throughout the Late Paleozoic. The Circum Arctic igneous activity close to Permian/Triassic boundary was manifested by basic volcanism on the Anjou Islands. Subsequent sedimentation was controlled by gentle vertical tectonic motions. This was succeeded by collision, folding and thrusting with emplacement of granite massifs on Bolshoi Lyakhov Island in Late Jurassic – Early Cretaceous. Angaucham Ocean was closed, and Anyui-Lyakhov suture and the Late Kimmerian fold basement formed. Flood basalt erupted in the De Long area in the Early Cretaceous. Cenozoic and Late Cretaceous sediments contemporaneous with the opening of the Eurasia Basin fill marginal shelf basins of the Arctic Ocean and pinch out towards the island highs. The Late Cretaceous age of the lowermost strata in the marginal basins is suggested by Cenomanian sediments overlapping weathered early Cretaceous rhyolite on Anjou Islands. Transgressive onlap at the base of late Oligocene- Miocene strata on the Anjou Islands and on nearby coastal mainland correlates with the Circum Arctic geodynamic restructuring. Short not traceable reflectors often observed within the acoustic basement suggest its possible correlation with Paleozoic and Mesozoic strata on Kotelny and Stolbovoy Islands showing gently dipping features within the fold and thrust tectonic basement. There is no evidence of regional metamorphism in Paleozoic and Mesozoic tectonic basement on Anjou Islands. It provides to distinguish solid (metamorphic) crust and sedimentary layer along with tectonic basement and sedimentary cover on tectonic maps. The sedimentary layer will comprise fold basement in cases similar to the observed on Kotelny Island. Fault tectonics on New Siberian Islands agrees with the formation of Laptev Sea and East Siberian Sea sedimentary basins in transtensional settings. However, in Cenozoic the basins fill was affected by transpressional deformation which complicates interpretation of MCS data.

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013