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Distribution, age, and origin of a submarine landslide deposit in the Pleistocene Kiwada Formation, forearc basin fill on the Boso Peninsula, east‐central Japan: Constraints from tephro‐ and biostratigraphy
Author(s) -
Utsunomiya Masayuki
Publication year - 2018
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/iar.12254
Subject(s) - geology , forearc , escarpment , paleontology , biostratigraphy , peninsula , pleistocene , structural basin , ridge , geomorphology , subduction , tectonics , history , archaeology
A mass‐transport deposit named MTD1 (up to 100 m in thickness) is intercalated in the upper Kiwada Formation, a Pleistocene forearc basin fill on the Boso Peninsula, east‐central Japan. The present study aims to examine the origin, age, and distribution of MTD1. MTD1 consists mainly of mudstone blocks containing thin very fine‐ to medium‐grained sandstones, and ranges from tens of centimeters to more than tens of meters in length and thickness. Correlation of marker tuff beds and application of the biostratigraphy of calcareous nannofossils suggest that the blocks in MTD1 were derived from the underlying strata. The total thickness of the stratified blocks from the different stratigraphic horizons exceeds 60 m, implying that MTD1 originated from deeply‐excavated slope failure. The slope failure occurred in a short time interval at ca 1.3 Ma. MTD1 provides an estimate of the height of the escarpment on the basis of the stratigraphic origin of the blocks.