Premium
Fault kinematics and past plate motions at a convergent plate boundary: Tertiary Shimanto Belt, southwest Japan
Author(s) -
Lewis Jonathan C.,
Byrne Timothy B.
Publication year - 2001
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/2000tc001239
Subject(s) - geology , paleogene , seismology , plate tectonics , clockwise , imbrication , kinematics , fault (geology) , convergent boundary , paleontology , structural basin , subduction , tectonics , rotation (mathematics) , geometry , oceanic crust , physics , mathematics , classical mechanics
Early‐ and late‐stage, outcrop‐scale faults have been documented in Paleogene strata of the Muroto Peninsula of southwest Japan. The former were active early in the consolidation history of the sediment and are crosscut by the latter, which were active after regional‐scale imbrication, folding, and penetrative deformation (i.e., regional, spaced pressure solution cleavage). Orientation distributions of striae and kinematic axes indicate that the two generations of faults reflect distinct kinematic regimes. The orientations and crosscutting relations indicate a counterclockwise (viewed downward) rotation of the principal shortening direction between early‐ and late‐stage faulting. Existing fossil and radiometric age data suggest this transition occurred during Eocene‐Oligocene time. The fault kinematic data are interpreted to reflect a change in relative plate motions between Eurasia and an oceanic plate subducting beneath Eurasia in Paleogene time. These results, coupled with existing paleothermal and paleopressure data, are consistent with the presence of a spreading ridge in the western Pacific basin during this time.