New data on the cenozoic deformations of the West Kamchatka Peninsula and their implications for the recent tectonics of the Eastern Sea of Okhotsk region

Abstract

The newly obtained data on the West Kamchatka complexes, together with the results published previously, allowed us to reach some conclusions regarding the Cenozoic kinematics in the eastern part of the Sea of Okhotsk region. The Cenozoic stress fields of submeridional-NW-SE trend were reconstructed. These results may provide independent evidence for the riftogenic opening model of the Sea of Okhotsk. On the other hand, the data might fit with the alternative concept of the effect of the collision process between the Indo-Australian and Eurasian plates concerning the Cenozoic structure of the Sea of Okhotsk region (including its eastern part). The stages of the principal regional phases of the structural development are shown. The NW-SE compression was the last and most essential stage of the structure formation and might, evidently, show a long-term response to the completion of the collision between the island arc of the Eastern peninsulas (Kronotskaya) and the Kamchatka Peninsula in the Middle-Late Miocene. In the recent and present-day intraplate geodynamic situation, the boundary between the hypothetic Sea of Okhotsk block and the Kamchatka Peninsula (the East Sea of Okhotsk fault zone) was mainly developed under the conditions of a left-side transpression and strike-slip setting. The comparison of the data obtained with the results of earlier detailed seismic surveys in the Sea of Okhotsk (the Deryugin Basin area) showed their general similarity.