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Paleomagnetism of a pyroclastic flow deposit and its correlative widespread tephra in central Japan: Possible tectonic rotation since the late Pleistocene
Author(s) -
Itoh Yasuto,
Kimura Haruo
Publication year - 2004
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.1440-1738.2003.00414.x
Subject(s) - geology , pyroclastic rock , paleomagnetism , tephra , pleistocene , paleontology , thermoremanent magnetization , clockwise , tectonics , sedimentary depositional environment , seismology , volcano , remanence , geomorphology , geochemistry , rotation (mathematics) , structural basin , magnetization , geometry , physics , mathematics , quantum mechanics , magnetic field
The late Pleistocene Kamitakara Pyroclastic Flow Deposit (KPFD) and its correlative Kasamori (Ks22) Tephra in central Japan are found to preserve stable thermoremanent magnetization (TRM) and detrital remanent magnetization (DRM), respectively. Untilted site‐mean declinations of the KPFD are characterized by a fairly large scatter with easterly deflection, while those of the Ks22 show significantly smaller deflections. Because northerly paleomagnetic directions consistently characterize shallow marine sediments intercalating the Ks22 layer, the directional discordance is not attributed to different acquisition timing between TRM and DRM, but is probably due to a recent tectonic rotation in central Japan. Large scatter in TRM declinations of the KPFD implies that a number of right‐lateral active faults around the depositional area of the pyroclastic flow raised differential rotation of crustal blocks in central Japan, even during the late Pleistocene.