Paleomagnetism and geochronology of the Late Cretaceous-Paleogene island arc complex of the Kronotsky peninsula, Kamchatka, Russia: Kinematic implications

The remnants of ancient island arcs are exposed in the Achayvayam-Valagina and East Peninsulas tectonic zones of the Olutor-Kamchatka region, northeas t Russia. Geochemically, Late Cretaceous to Paleogene island are complexes of the East Peninsulas zone are similar to intraoceanic island arcs, and th e East Peninsulas zone is regarded as the extinct Kronotsky island are. Pal eomagnetic and biostratigraphic studies of Late Cretaceous and Paleogene is land are rocks were carried out at 21 sites in the eastern part of the Kron otsky Peninsula, which belongs to the East Peninsulas zone. Characteristic remanent magnetizations of both polarities isolated from most sites pass re versal and fold tests; the Cretaceous result is also supported by a positiv e conglomerate test on lava boulders from an intraformational conglomerate. Mean inclinations of Late Cretaceous, Ypresian and Bartonian rocks corresp ond to paleolatitudes of 44.8 degrees +/- 8.0 degrees N, 38.6 degrees +/- 3 .5 degrees N, and 45.1 degrees +/- 7.0 degrees N. respectively. These value s are similar to 20 degrees lower than the corresponding reference values f or the North American plate for the Cretaceous and Ypresian and similar to 14 degrees lower for the Bartonian. Therefore northward transport of the Kr onotsky island are is indicated. Kinematic evolution of the Kronotsky islan d are in the Late Cretaceous-Paleogene was reconstructed using published ki nematic parameters. In addition, we incorporated into analysis the geologic al and published paleomagnetic data for the Late Cretaceous and Tertiary is land are complexes of the Cape Kamchatka Peninsula from the East Peninsulas zone and the Late Cretaceous island-are complexes of the Achayvayam-Valagi na zone. As a result, two alternative scenarios of kinematic evolution for the Kronotsky island are are proposed. According to both of them, the Krono tsky island are was moving with the continental plate in Late Cretaceous ti me and with the Pacific plate from the beginning of the Paleocene until doc king with the Eurasian margin in Miocene-Pliocene time.