Middle to Late Miocene foredeep basin successions in an arc-arc collision zone, Northern Tanzawa mountains, Central Honshu, Japan

Abstract

Middle to Late Miocene coarse siliciclastic and volcaniclastic deposits are distributed along a narrow longitudinal reverse fault and fold belt between the Kanto and Tanzawa mountains, central Honshu, Japan. The coarse clastic piles represent foredeep basin successions characterized by a progressive shallowing sequence from basin plain, through submarine volcano-submarine fan/slope, to fan delta systems. The siliciclastic deposits are clastic wedges that prograded directly into and down the axis of the foredeep basin during the uplift and progressive unroofing of the orogenic northern highlands of the Kanto Mountains. This was accompanied by syndepositional deformation of the basin fills which is mainly represented by the northward tilting and gave rise to active longitudinal drainage on the southern flank of the Kanto Mountains. Interbedded volcaniclastic deposits, on the other hand, were mainly derived from small submarine volcanoes emplaced on the landward basin slope and may represent near-trench magmatism. Evolution of the foredeep basin successions can be explained by collision of the Tanzawa Block (a paleo-volcanic island) with central Honshu (Honshu Arc) since the Late Miocene, following northward subduction of the Izu-Bonin volcanic arc (ridge) which was emplaced by westward subduction of the Pacific Plate beneath the Philippine Sea Plate.