--> Abstract: Granitoid Magmatism in Tectonic Evolution of Arctic Continental Margin of Chukotka, by Marina Luchitskaya; #90177 (2013)

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Granitoid Magmatism in Tectonic Evolution of Arctic Continental Margin of Chukotka

Marina Luchitskaya

Arctic continental margin of Chukotka formed as a result of collision between Chukotka microcontinent (Anuyi-Chukotka fold system) and structures of Siberian active margin (Alasey-Oloy fold system). Closure of oceanic space was followed by South-Anyui suture formation. Anuyi-Chukotka fold system (ACFS) includes ancient Precambrian basement and intensively deformed Paleozoic-Mesozoic sedimentary cover. ACFS is composed of several terranes or subterranes: Vrangel, Anuyi, Chauna, Bering, which have distinct stratigraphical, lithological and structural differences. Basement and cover are intruded by numerous granitoid intrusions, which earlier were subdivided into Early Cretaceous (collisional) and Late Cretaceous, related to Okhotsk-Chukotka volcanic belt formation. Last year’s new data, indicating repeated intrusions of granitoid in geological evolution of Arctic margin of Chukotka, appeared (Natal'in et al., 1999; Katkov et al., 2007; Miller et al., 2009; Tikhomirov et al., 2011; Luchitskaya et al., 2012; Akinin, 2011; Akinin et al., 2012). Thus, following stages of granitoid magmatism may be distinguished: (1) 609–677 Ma (Kos'ko et al., 1993), 650–550 Ma (Natal'in et al., 1999), 580–650 Ma (Akinin, 2011); (2) 375–369 Ma (Natal'in et al., 1999), 380–360 Ma (Akinin et al., 2012) and 352, 353 Ma (Luchitskaya et al., 2013); (3) 142–145 Ma (Akinin et al., 2012), 135 Ma (Luchitskaya et al., 2012), Valanginian-Hauterivian (Zhulanova et al., 2007); (4) 127–100 Ma (Katkov et al., 2007; Miller et al., 2009; Tikhomirov et al., 2011; Akinin et al., 2012); and (5) 100–77 Ma. Neoproterozoic stage is related to formation of crystalline basement of Chukotka microcontinent. Paleozoic stage is correlated to Ellesmerian orogeny and indicates similarity to terranes of Arctic Alaska. Detrite zircons of this age are typical for Triassic sandstones of Chukotka (Miller et al., 2006). Origin of third stage granitoid magmatism is problematic. Its age correlates to intensive closure of South-Anyui oceanic basin and syncollisional stage. Possibly intrusion of granitoids resulted from destruction and thickening of subducting continental lithosphere of Chukotka microcontinent. Forth stage corresponds to postcollisional extension, formation of granite-metamorphic core complexes and overlapping basins (onshore – Aynakhkurgen, Nutesyn et al.) and offshore – South-Chukotka trough). Fifth stage correlates to formation of Andean type margin (Okhotsk-Chukotka volcanic belt). At the same time one granitoids were directly related to volcanic series formation, others may intrude as dikes and small intrusions in the back-arc of Andean margin. Work was supported by RFBR projects 13-05-00249, 11-05-00074, Scientific school # NSh-5177.2012.5, Programme ONZ 10

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