Paleomagnetism, tectonics and oil geology of the Koryak region, northeastern Russia

The results of paleomagnetic, tectonic, geochemical studies and new {dollar}sp{lcub}40{rcub}{dollar}Ar/{dollar}sp{lcub}39{rcub}{dollar}Ar ages are employed to make a tectono-stratigraphic interpretation of the Koryak region of Russia. On the bases of composition, internal structure, age of the rocks and the age of accretion, three first-order tectono-stratigraphic units may be distinguished within the Koryak region. From southeast to northwest, these are the Olyutorsky superterrane, Ukelayat terrane and Koryak superterrane.; Paleomagnetic investigation of basalt and sedimentary units of Campanian to Paleocene age from the Olyutorsky superterrane reveals a characteristic pre-folding remanent magnetization during stepwise thermal and alternating field demagnetization. Interpretation of paleomagnetic results shows 21{dollar}spcirc{dollar} to 26{dollar}spcirc{dollar} of northward motion for Late Maastrichtian rocks and 46{dollar}spcirc{dollar} of northward motion for Campanian rocks with respect to the North American plate. The observed paleolatitudes agree well with terrane trajectories calculated using published Izanagi-North America and Kula-North America finite rotations and provide evidence that the Izanagi and Farallon plates were bounded by an island arc system in the western Pacific, fragments of which are preserved today as tectonostratigraphic terranes.; Within the Koryak superterrane, Early Jurassic and, possibly, Late Paleozoic, mid-ocean ridge basalt flows and sheeted dike complex are intruded by Early Cretaceous boninite. Paleomagnetic study of these rocks, known collectively as Kuyul ophiolite complex, suggests deposition of the older units approximately 32{dollar}spcirc{dollar} to 47{dollar}spcirc{dollar} south of their expected location on the North American continental margin while the younger units show no significant displacement with respect to either the North America or Eurasia plates. The {dollar}sp{lcub}40{rcub}{dollar}Ar/{dollar}sp{lcub}39{rcub}{dollar}Ar ages are often significantly younger than the fossil ages in the studied region. This inconsistency is attributed to a regional thermal event, presumably related to terrane collision.; Tertiary sedimentary basins of the Bering Sea region developed on a basement consisting of different tectonostratigraphic terranes during the Paleocene to Miocene. Based on new data a kinematic model explaining the formation, migration and characteristics of the hydrocarbons of this region is proposed.