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Late Paleocene–middle Miocene pelagic sequences in the Boso Peninsula, Japan: New light on northwest Pacific tectonics
Author(s) -
MOHIUDDIN MIA MOHAMMAD,
OGAWA YUJIRO
Publication year - 1998
Publication title -
island arc
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.554
H-Index - 58
eISSN - 1440-1738
pISSN - 1038-4871
DOI - 10.1111/j.1440-1738.1998.00191.x
Subject(s) - geology , peninsula , paleontology , tectonics , pelagic zone , pelagic sediment , late miocene , oceanography , seismology , sedimentary rock , archaeology , geography , structural basin
Late Paleocene–middle Miocene pelagic limestone/chert sequences from the Mineoka Tectonic Belt, Boso Peninsula, central Japan, were biostratigraphically studied for planktic foraminifer fossils for the first time. The rock units are included as several isolated blocks tectonically within the ophiolitic mélange together with the Mio‐Pliocene Honshu arc‐derived terrigenous and Izu Arc‐derived volcaniclastic materials. The pelagic sequences are grouped into the newly proposed Kamogawa Group which is subdivided into the Paleocene Nishi Formation, Eocene–Oligocene Heguri‐Naka Limestone and early–middle Miocene Shirataki and Heguri Formations. This study of Kamogawa Group pelagic sequences throws new light on tectonic modeling of plate accretion to the unique trench–trench–trench (TTT)‐type triple junction area off the Boso Peninsula. Different formations of the Kamogawa Group have different tectonic and paleogeographic significances for the oceanic plate with a seamount that was approaching the Izu and Honshu arcs during Pacific plate subduction, and that was accreted to the Honshu Arc during the middle Miocene.