HR: 0800h
AN: GP41A-0821    [Abstracts]
TI: Structure and evolution of the inner parts of collisional orogens of Verkhoyansk-Chukotka area (North-Eastern Asia)
AU: * Oxman, V S
EM: oxman@diamond.ysn.ru
AF: Institute of Diamond and Precious Metal Geology, Lenina avenue 39, Yakutsk, 677005 Russian Federation
AU: Sokolov, S D
EM: sokolov@ginras.ru
AF: Geological Institute, Pyzhevsky 7, Moscow, 119017 Russian Federation
AU: Bondarenko, G Y
EM: g.bondarenko@promgaz.gazprom.ru
AF: Institute PROMGAZ, Nametkina 6, Moscow, 117 420 Russian Federation
AB: The Mesozoic Verkhoyansk-Chukotka orogenic area consists of Verkhoyansk-Kolyma and Chukotka-Anuyi orogenic belts. External part of Verkhoyansk-Kolyma orogen (Verkhoyansk fold-and-thrust belt) includes Paleozoic to Mesozoic shelf sediments and turbidite of the Asian continental margin. The inner part (Chersky belt) consists of several continental terranes. These complexes have been tectonically overlapped by allochthones of ophiolite and polymetamorphic rocks. Back part (Alazeya-Oloy belt) contains deformed Paleozoic to Mesozoic island arc volcano-terrigenous rocks. Early accretion deformations (Middle Jurassic) were connected with the Kolyma-Omolon microcontinent and Asia craton amalgamation. This event was fixed by thrusts, nappes, and recumbent and overturned folds of north-east vergence. Late oblique collisional (Late Jurassic-Neocomian) deformations were characterized by combine kinematics with sinistral transpression component, and counter clockwise rotation of convergent structures. Chukotka-Anuyi orogen is limited in the south by allochtones of island arc rocks of the Alazeya-Oloy belt. The northern vergent nappes of the inner part consist of ophiolite, Late Paleozoic-Mesozoic volcano-terigenous rocks and accretion melange. The autochthone includes high-deformed Triassic turbidite of the Chukotka-Arctic Alaska microcontinent passive margin. The nappes were overlapped Hauterivian-Barremian neoautochthone. The north vergent nappes were formed during early Valanginian-Hauterivian event of collisions. The structures of the Verkhoyansk-Kolyma and Chukotka-Anyui orogenic belts are formed as a result of accretion and collision of Kolyma-Omolon and Chukotka-Arctic Alaska microcontinents to the continental margins of Siberian and North-Asian cratons. Orogenic belts of the Verkhoyansk - Chukotka area appeared as a result of closing small oceanic basins, representing segments of Protoarctic ocean. Supported by RFFI (grants 02-05-64217, 03-05-64915, 03-05-96074).
DE: 8015 Local crustal structure
DE: 8102 Continental contractional orogenic belts
DE: 5475 Tectonics (8149)
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2004 AGU Fall Meeting