Age dating fault gouge
Calcite precipitated in veins at the Har Zefiyya Fault was controlled by near-surface karst processes.
Initial opening of the veins occurred prior to about 500 ka and may represent the onset of an east–west contractional deformation.
The clay fabrics in fault rocks are poorly developed, indicating that fluids were not confined to the fault zone by preferentially oriented clays; rather we propose that fluids in the illite-rich gouge were isolated by adjacent lower permeability, illite-smectite-bearing rocks in the damage zone.
We report two Ar-40/Ar-39 illite ages from fault gouge directly above the current trace of the Alpine Fault in New Zealand at Gaunt Creek (1.36 /- 0.27 Ma) and Harold Creek (1.18 /- 0.47 Ma), and one Ar-40/Ar-39 illite age from fault gouge from the Two Thumbs Fault on the east side of the Southern Alps.
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It is essential to understand the activity of faults in and around a target area to assess the long-term geosphere stability for geological isolation.
Potassium-Argon (K-Ar) dating of fault gouge has been conducted in Tono Geoscience Center as one of the dating technique for faulting.
We infer that the fault gouge ages record faulting and gouge formation as the rocks passed very rapidly through the brittle-ductile transition zone on their way to the surface.
This report includes methods for sample preparation, analyses, and age calculation on the K-Ar dating.
This can contribute to an evaluation of calculated K-Ar ages.
), AB(CSIRO Energy, 26 Dick Perry Avenue, Kensington, WA 6151, Australia), AC(GFZ German Research Centre for Geosciences, 14473 Potsdam, Germany), AD(GNS Science, Dunedin, New Zealand), AE(School of Earth Sciences, Victoria University, Wellington, New Zealand), AF(Department of Geosciences, University of Arizona, Tucson, AZ 85721-0077, USA), AG(Insitut für Geowissenschaften, Universität Tübingen, 72070 Tübingen, Germany), AH(Pamukkale University, Department of Geological Engineering, 20070 Denizli, Turkey)Ar ages of 2.04 ± 0.3 Ma at Gaunt Creek and 11.46 ± 0.47 Ma at Harold Creek.
We also report Rb-Sr muscovite-based multimineral ages of Alpine Schist mylonite adjacent to the dated fault gouge at Harold Creek (13.1 ± 4.3 Ma) and Gaunt Creek (8.9 ± 3.2 Ma).