HR: 0800h
AN: GP41A-0819    [Abstracts]
TI: Tectonic History and Metallogeny of the Chukchi Terrane
AU: Byalobzhesky, S
EM: goryachev@neisri.magadan.ru
AF: North East Interdisciplinary Science Research Institute, 16 Portovaya St., Magadan, 685000 Russian Federation
AU: * Goryachev, N A
EM: goryachev@neisri.magadan.ru
AF: North East Interdisciplinary Science Research Institute, 16 Portovaya St., Magadan, 685000 Russian Federation
AB: The Chukchi Terrane consists of the Anyui, Wrangel, Chaun and Bering Sub-Terranes; at present, it is the northern part of the Pacific Folded Belt. Its basement is composed of folded rocks of Proterozoic and Paleozoic, which crop out on Wrangel Island, the Kuul and Alyarmaut Uplifts, Chukotka and Seward Peninsulas. Early Precambrian blocks may be also present in it. The above-mentioned sub-terranes have a similar development history and are featured by the same type of Mesozoic metamorphism, magmatism and metallogeny. Its tectonic history has been as follows: 1. Late Proterozoic and Early Paleozoic (pre-Visean) magmatism, thrusting, isoclinal folding. Scarce occurrences of gold and stibnite mineralization. 2. An unconformity at the base of Visean - Mid Carboniferous section with basal conglomerates contain granite pebbles and boulders. 3. Permian uplifting (continental), reduced sedimentation. 4. Maximum sedimentation in Triassic time accompanied by Early Triassic rifting and dominating turbidite rocks. The problem is the provenance areas for large amounts of terrigenous rocks. 5. Lack of sediments characterisitc of the greatest part of early Jurassic (post-Sinemurian), middle Jurassic and late Jurassic (pre-Volgian) time periods. Uplifting is correlative with the extension stage in the South-Anyui Ocean. 6. Late Jurassic - Neocomian. Intense uplifting processes occured at the end of late Jurassic and in early Cretaceous and associated with intrusion of subduction- and collision-related granitoids (147-140 Ma). The Nutesyn marginal continental arc was forming over the southern periphery of terrane and flysch processes occurred there through Neocomian. Fault-related depressions were developing in the north of the area under consideration. Since late Jurassic, as a result of an approach (with a right-side fault shifting) of the Novosibirsk-Chukchi Super-Terrane and the northeastern edge of the Asiatic Craton, the Yuzhno-Anyui Ocean began to close from west to east. Insignificant polymetallic and gold-tin-polymetallic mineralization types, and major tin lode deposits (Val'kumei) were developing. This was the first stage of tin mineralization. 7. Termination of the ocean closing process at the end of Neocomian (Barremian - early Albian); an outburst of granitoid magmatism (120 - 100 Ma) and formation of granite metamorphic domes. The main stage in the history of gold-quartz mineralization (Karalveem, Sovinoe, Ozyornoe, Ichuveem, Rock Creek, Big Hurrah, etc.) and may be silver-base metallic (Chechekuyum), and tin lode deposit Pyrkakai (cassiterite-quartz stockworks. 8. Cessation of an intense magmatic activity in late Albian - Campanian related to formation of the post-accretion Okhotsk-Chukchi Volcanic Belt (Chukotka). Termination of development of granite metamorphic domes; the third cycle of subduction-related granite magmatism (90 - 70 Ma). The main stage in the history of tin-tungsten-beryllium (Iultin, Lost River) and gold-silver mineralization types (Valunistoye). 9. Extension processes at the end of Neogene associated with formation of intraplate alkali basalt volcanoes.
DE: 8102 Continental contractional orogenic belts
DE: 8105 Continental margins and sedimentary basins
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2004 AGU Fall Meeting