Fabric transition with dislocation creep of a carbonate fault zone in the brittle regime

• Published in: Tectonophysics Vol. 723; pp. 107 - 116
• Main Authors: Kim, Sungshil, Ree, Jin-Han, Han, Raehee, Kim, Nahyeon, Jung, Haemyeong
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 16.01.2018; Elsevier BV
• Subjects: Calcite; Cambrian; Carbonates; Deformation; Dislocations; Dolostone; Ductile-brittle transition; Fabric transition; Fabrics; Fault zones; Fracture mechanics; Frictional heating; Garam thrust; Geological faults; Heating; High temperature; Lattice preferred orientation; Limestone; Materials creep; Minerals; Moisture content; Ordovician; Preferred orientation; Seismic activity; Seismic slip; Slip; Solifluction; Strain rate; Temperature; Temperature gradients; Twinning; Water content; Frictional heating; Lattice preferred orientation; Seismic slip; Garam thrust; Fabric transition
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/j.tecto.2017.12.008

Fabric transition by a switch in the dominant slip system of minerals in the plastic regime can be induced by changes in temperature, strain rate, or water content. We propose here this fabric transition by frictional heating in seismogenic fault zones in the brittle regime. The Garam Thrust in the Taebaeksan Basin of South Korea has a hanging wall of Cambrian dolostone juxtaposed against a footwall of Ordovician limestone and records a minimum displacement of ~120m. In a 10cm thick plastically deformed layer adjacent to the principal slip layer of the fault zone, the lattice preferred orientation of calcite grains suggests that the dominant slip system changes, approaching the principal slip layer, from r 〈02–21〉 and e-twinning, through r 〈02–21〉 and basal 〈a〉, to basal 〈a〉. This fabric transition requires a high temperature-gradient of 40°C/cm, which we infer to result from frictional heating of the seismic fault zone. We suggest that fabric transition within a thin plastically deformed layer adjacent to the principal slip layer of a fault zone indicates an unusually steep temperature gradient and provides strong evidence of seismic slip. •Fabric transition induced by frictional heating in the brittle regime.•Narrow layer of plastic deformation adjacent to seismic slip zone in carbonate thrust.•Microfabrics implying an unusually steep temperature gradient in a fault zone provide strong evidence of seismic slip.