Relationship between tectonics, volcanism, sedimentation and basin development, Late Cenozoic, central part of Northern Honshu, Japan

Abstract

A pronounced interplay between tectonics, volcanism and sedimentation can be established in the volcanic arc region of the central part of Northern Honshu during the Early Miocene to Quaternary interval. Four stages are recognized with the type of volcanism and sedimentation varying according to the tectonic stress regime. 1. (1)| Rifting stage (22?–15 Ma). NS-trending half grabens were formed under an extensional stress regime related to the rifting of the Sea of Japan. Basins were rapidly filled by intermediate to felsic volcanic products, which are often associated with subaerial fluvial and lacustrine sediments. 2. 2)| Back-arc Basin Opening Stage (15-13 Ma). With more advanced stagess of rifting, subsidence from crustal stretching resulted in marked marine incursion, and an overall transgressive succession developed. During this stage, the back-arc side of Northern Honshu subsided rapidly to middle bathyal environments. At the same time, associated with the opening of the Sea of Japan, large volumes of regionally extensive mafic lavas and associated hyaloclastites were erupted within submarine grabens. In contrast, in the present Backbone Ranges, felsic volcanism occurred within bathyal to shallow marine environments. Igneous rock types in this stage display a bimodal mafic-felsic chemistry. 3. (3)| Transitional Stage (13-2.4 Ma). (a) Thermal Subsidence Substage (13-8 Ma). An intermediate stress regime developed, which included phases of both weak extension and compression. Consequently, grabens along the Sea of Japan ceased to form. Later, lithospheric cooling eventually led to thermal subsidence of the back-arc region, and hemipelagic sediments mantled the previously active mafic volcanic apron. Volcanism at this time was mainly restricted to a narrow zone along the present Backbone Ranges where felsic to intermediate volcanic products accumulated within shallow marine environments. (b) Incipient Compressional Substage (8-2.4 Ma). Hemipelagic sedimentation continued on the back-arc side of Northern Honshu. Along the present Backbone Ranges, the intermediate stress regime continued, with formation of many large caldera structures associated with subaerial felsic volcanism. 4. (4)| Shortening Deformation Stage (2.4 Ma-present). The change of the absolute direction of motion of the Pacific plate at the Early to Middle Pliocene changed the regional stress regime of the volcanic arc from intermediate to compression. Movement of back-arc thrusts along the Sea of Japan coast began 2–3 Ma and led to uplift of the volcanic arc. Continued compression in the volcanic arc produced narrow uplifted zones, with associated basins bounded by reverse faults. These basins were filled rapidly by terrestrial sediments containing upward-coarsening sequences. Under this highly compressional tectonic stress regime, volcanism became intermediate-mafic in composition, with large stratovolcanoes becoming prominent.