HR: 0800h
AN: GP41A-0814 INVITED     [Abstracts]
TI: Tectonics of the South Anyui suture: present day version
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: PROMGAS Institute, Nametkina 6, Moscow, 117 420 Russian Federation
AU: Layer, P W
EM: player@gi.alaska.edu
AF: University of Alaska Fairbanks, 900 Yukon Drive, Fairbanks, 755780 United States
AB: The South Anyui Suture (SAS) is one of the most prominent tectonic elements of North-East Asia separating the Verkhoyansk-Kolyma and Anyui-Chukotka fold belts. Following the Seslavinsky (1979), Parfenov (1984), and Natal'in (1984) the SAS is recognized as result of late Mesozoic collision between Siberia and North America continents. Many aspects of the SAS geology and evolution remain poorly understood: (i) the timing of the oceanic basin in-ception and existence; (ii) the inner structure and deformational history; (iii) the age and genesis of the ophiolites; (iv) the island-arc units distribution and age. Main results of our research in the SAS are: (1) The north vergent thrust structure is recog-nized. The autochthone includes shelf and slope sequences of the Chukotka microcontinent. The allochthone thrust package consists of ophiolitic, metamorphic, terrigenous, and island-arc rocks; (2) Late Mesozoic subduction related chaotic and intra oceanic island arc units are recognized; (3) A Bathonian-Callovian age of basalt-chert oceanic assemblages, previously reported as Late Jurassic to Neocomian; (4) A new 40Ar/39Ar data for: (i) Vurguveem ophio-litic gabbro 312.2 ñ 11.1 I…, (ii) diabase dike from Aluchin ophiolite 226.6 ñ 10.5 I…, (iii) amphibolites in the metamorphic sole of Uyamkanda ophiolite 239.1 ñ 3.8 I…, (iv) green-schists at the base of tectonic sheet 156.5 ñ 3.9, 120.6 ñ 3.5, 115.2 ñ 1.3, 108.4 ñ 1.2, and 104.1 ñ 2.8 I…. According new data tectonic evolution of SAS can be suggested the following: (1) Anyui oceanic basin existed from Mississippian to Neocomian; (2) Northern (present-day coordi-nates) margin of ocean was passive, and southern margin was active; (3) Oceanic spreading was stopped in Oxfordian, probably simultaneously with start of Canada basin opening (Grantz et al. 1998); (4) The collision accompanied by subduction of Chukotka passive mar-gin beneath the Siberia active margin; (5) Pre-collisional deformations was related with sub-duction; (6) Collisional deformations during Hauterivian to Aptian include two phases: early - thrust fault related and late - strike-slip fault related; (7) Post-collisional Albian to Senoma-nian deformations was produced by extensional event. Supported by RFBR (grant 02-05-64217), FCP "Integratsiya" (grant 0382).
DE: 8102 Continental contractional orogenic belts
DE: 8110 Continental tectonics--general (0905)
DE: 0905 Continental structures (8109, 8110)
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2004 AGU Fall Meeting