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Present‐day principal horizontal stress orientations in the Kumano forearc basin of the southwest Japan subduction zone determined from IODP NanTroSEIZE drilling Site C0009
Author(s) -
Lin Weiren,
Doan MaiLinh,
Moore J. Casey,
McNeill Lisa,
Byrne Timothy B.,
Ito Takatoshi,
Saffer Demian,
Conin Marianne,
Kinoshita Masataka,
Sanada Yoshinori,
Moe Kyaw Thu,
Araki Eiichiro,
Tobin Harold,
Boutt David,
Kano Yasuyuki,
Hayman Nicholas W.,
Flemings Peter,
Huftile Gary J.,
Cukur Deniz,
Buret Christophe,
Schleicher Anja M.,
Efimenko Natalia,
Kawabata Kuniyo,
Buchs David M.,
Jiang Shijun,
Kameo Koji,
Horiguchi Keika,
Wiersberg Thomas,
Kopf Achim,
Kitada Kazuya,
Eguchi Nobuhisa,
Toczko Sean,
Takahashi Kyoma,
Kido Yukari
Publication year - 2010
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2010gl043158
Subject(s) - geology , forearc , accretionary wedge , subduction , seismology , borehole , drilling , paleontology , tectonics , mechanical engineering , engineering
A 1.6 km riser borehole was drilled at site C0009 of the NanTroSEIZE, in the center of the Kumano forearc basin, as a landward extension of previous drilling in the southwest Japan Nankai subduction zone. We determined principal horizontal stress orientations from analyses of borehole breakouts and drilling‐induced tensile fractures by using wireline logging formation microresistivity images and caliper data. The maximum horizontal stress orientation at C0009 is approximately parallel to the convergence vector between the Philippine Sea plate and Japan, showing a slight difference with the stress orientation which is perpendicular to the plate boundary at previous NanTroSEIZE sites C0001, C0004 and C0006 but orthogonal to the stress orientation at site C0002, which is also in the Kumano forearc basin. These data show that horizontal stress orientations are not uniform in the forearc basin within the surveyed depth range and suggest that oblique plate motion is being partitioned into strike‐slip and thrusting. In addition, the stress orientations at site C0009 rotate clockwise from basin sediments into the underlying accretionary prism.