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Rapid intra‐arc rifting in Miocene northeast Japan
Author(s) -
Yamaji Atsushi
Publication year - 1990
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/tc009i003p00365
Subject(s) - rift , geology , subsidence , lithosphere , thermal subsidence , seafloor spreading , tectonic subsidence , seismology , paleontology , basement , crust , tectonics , structural basin , civil engineering , engineering
Although life‐times of major continental rifts are tens of millions of years, intra‐arc rifting in Miocene NE Japan lasted for only about 3 m.y. before back arc spreading began. The rate of initial subsidence was over 1 km/m.y., much faster than that in major continental rifts. Thus this intra‐arc rift evolved 10 times as fast as major intracontinental rifts. The large temperature dependence of lithosphere rheology and the hot thermal regime of island arc lithosphere account for the rapid rifting. Less than 1 m.y. before the rifting‐spreading transition, the inner NE Japan arc subsided from shallow marine depths to middle or lower bathyal depths (1.0–2.5 km). The average total basement subsidence was 2–3 km during the rifting. The rapid submergence occurred during one third of the duration of rifting but accounts for two thirds of the total subsidence during rifting. Namely, the initial subsidence rate accelerated toward the time of breakup of the arc crust. At the same time, the region along the present Pacific coast remained only shallow marine or terrestrial throughout, presumably influenced by global eustacy.