Deformational environment of the Pleistocene Ashigara group along the northern margin of the Philippine sea plate

Kenta KOBAYASHI; Masato KONAKAWA

Presentation information

Oral

Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS30] Evolution of the Pelagic Realm

Tue. May 26, 2015 11:00 AM - 12:45 PM 304 (3F)

Convener:*Atsushi Matsuoka(Department of Geology, Faculty of Science, Niigata University), Toshiyuki Kurihara(Graduate School of Science and Technology, Niigata University), Yasuhiro Kato(Department of Systems Innovation, Graduate School of Engineering, University of Tokyo), Tetsuji Onoue(Earth and Environmental Sciences, Graduate School of Science and Technology, Kumamoto University), Katsunori Kimoto(Japan Agency for Marine-Earth Science and Technology), Tatsuo Nozaki(Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology), Hayato Ueda(Department of Geology, Niigata University), Kenta Kobayashi(Department of Geology, Faculty of Science, Niigata University), Takashi Hasegawa(Division of Global Environmental Science and Engineering, Graduate School of Natural Science and Technology, Kanazawa University), Chair:Tetsuji Onoue(Earth and Environmental Sciences, Graduate School of Science and Technology, Kumamoto University), Atsushi Matsuoka(Department of Geology, Faculty of Science, Niigata University)

12:29 PM - 12:32 PM

[MIS30-P04] Deformational environment of the Pleistocene Ashigara group along the northern margin of the Philippine sea plate

3-min talk in an oral session

Kenta KOBAYASHI¹, *Masato KONAKAWA² (1.Dep. Geol., Fac. Sci., Niigata Univ., 2.Grad. Sch. Sci. & Tech., Niigata Univ.)

Keywords:Kanagawa Prefecture, Ashigara group, Shiozawa formation, cataclasite, coalification, Philippine sea plate

On the northern convergence border of the Philippine Sea plate, Pleistocene Ashigara group (1.6-0.5Ma) filled a trough. Miocene Tanzawa group is distributed on the north side, and both are bounded with the Kannawa fault system. The Kannawa fault system is divided into five groups of active faults (e.g. Shiozawa fault system: NE-SW, sinistral-reverse). The Shiozawa formation (conglomerates) which is the high-end strata of the Ashigara group is distributed over the southeastern side of the Shiozawa fault. Parts of the conglomerates are deformed remarkably. P-R1 cataclasites are distributed over the range of 600m from the Shiozawa fault. The shear sense is reverse fault mainl. Quartz grain becomes fine fragment by crush, and biotite does basal slip, it is thought that this cataclasite was formed under environment of 250-300 oC, and 10km in depth. It is necessary to assume uplift rate more than 10m/Ka or an abnormally high geothermal gradient.