THE RELATIONSHIP BETWEEN LATE CENOZOIC TECTONIC EVENTS AND STRESS-FIELD AND BASIN DEVELOPMENT IN NORTHEAST JAPAN

The regional tectonic stress field, basin development, and crustal deformation of the NE Japan are in the interval between 32 Ma to the Quaternary can be synthesized based on dike, vein, and fault Orientation data, as well as on the compilation of the regional geology. An extensional stress field became prevalent from 32 Ma, and major normal faulting started at 25-20 Ma, which resulted from back are rifting. Normal faulting, trending nearly parallel to the are, propagated from the present Japan Sea coast to the forearc side, following the trenchward migration of the main volcanic field. From 20 to 15 Ma, normal faults with an oblique trend to the are developed due to the counterclockwise rotation of NE Japan. The rapid clockwise rotation of SW Japan since 16 Ma produced a NW-SE directed transtensional stress regime in the NE Japan are. Due to crustal stretching associated with this pull-apart movement, the back are side of the NE Japan are subsided rapidly to middle bathyal environments. After the termination of the opening of the Japan Sea at about 14 Ma, a neutral stress regime prevailed, which included phases of both weak extension and compression. Lithospheric cooling eventually led to thermal subsidence of the back are region, and igneous underplating caused uplift of the axial zone of the volcanic are. The increase in velocity of the westward motion of the Pacific plate at around 4 Ma produced strong compression across the are, reactivating most of the Miocene normal faults, and uplifting the volcanic nrc. The greatest crustal shortening occurred in areas that were stretched the most in the Miocene within the volcanic are, which implies tectonic inversion.