Upper Jurassic-Lower Cretaceous sincollisional sedimentary sequences of Chukotka: sedimentation, structural style and geodynamic implications

Upper Jurassic-Lower Cretaceous sincollisional sedimentary sequence, exposed on the Central part of Northern Chukotka is critical for understanding the timing, dynamics and sedimentary setting evolution of Chukotka-Eurasia collisional process (e.g., Sokolov et al., 2002) and so, represents one of the key regional stratigraphic units (Til'man, 1973; Tibilov, 1982; Miller et al., 2002,2007). From the other hand, this research may shed the light on the widely discussing problem of the Canadian and Makarov basins opening (e.g., Miller, Verzhbitsky, in press). Field observations reveal moderately to weakly deformed terrigenous sediments of the first stage of deposition with visible and dispersal plants remnants and containing organic-rich beds. Widely distributed and intensively deformed Triassic sequences (Tuchkova et al., 2007) and discussing Jurassic-Cretaceous units both intruded by Aptian-Albian postcollisional plutons and dikes (e.g., Katkov et al., 2006). Collisional-related fabric and subsequent granitoids are complicated by small-scale latest normal faults, in particular related to the westernmost segment of South Chukchi (Hope) basin development in Upper Cretaceous(?)-Cenozoic. We believe, that Upper Jurassic-Lower Cretaceous chukotkian formation, overthrusted by Triassic (and Paleozoic?) sequences (Tibilov, 1982; Baranov, 1995), continues offshore to the Eastern Siberian and Chukchi Seas and play significant role in the structure of the Eastern Arctic Russian shelf. The work is supported by the Russian Foundation for Basic Research (grant 08-05-00547), program of ONZ RAS, and NSH-3172.2008.5.