Deformation conditions and kinematics of fault rocks in the Hatagawa Fault Zone and the Shajigami Shear Zone, Northeast Japan: Insights from calcite and quartz microstructures

Shunsuke Watanuki, Tsukasa Hisada, Jun Onoda, Shuya Hisasue, Takuto Kanai, Hideo Takagi

Research output: Contribution to journalArticlepeer-review

Abstract

Calcite grains are plastically deformed at lower temperatures than are quartz grains, which means that investigating the microstructures of both minerals should provide useful information regarding the deformation history of faults. We investigated the conditions of deformation and kinematics of fault rocks within the Hatagawa Fault Zone and the Shajigami Shear Zone, Northeast Japan, using deformation microstructures and crystallographic preferred orientations of quartz and calcite. The Hatagawa Fault Zone trends NNW–SSE, and the associated foliated granite cataclasites show sinistral shear. Limestone mylonite samples showing sinistral shearing display girdles of calcite c-axes close to the YZ plane and Z-maximum, suggesting relatively high and low temperatures of deformation, respectively. The Shajigami Shear Zone trends NE–SW, and quartz microstructures in granodiorite mylonites of the shear zone indicate dislocation creep at temperatures of 400–500 °C. The limestone mylonites have Z-maximum patterns of calcite c-axes. These fault rocks were deformed during the Cretaceous (before the Cenozoic 40° counterclockwise rotation of Northeast Japan) in a kinematic framework characterized by a shortening direction that rotated from N–S to NW–SE. The kinematics and deformation ages of the fault rocks correspond to a change in the direction of motion of the Izanagi Plate at c. 100 Ma.

Original languageEnglish
Article number104046
JournalJournal of Structural Geology
Volume137
DOIs
Publication statusPublished - 2020 Aug

Keywords

  • Crystallographic preferred orientation
  • Foliated cataclasite
  • Hatagawa fault zone
  • Kinematics
  • Mylonite
  • Shajigami shear zone

ASJC Scopus subject areas

  • Geology

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