Dating fault reactivation by Ar/Ar laserprobe: an alternative view of apparently cogenetic mylonite–pseudotachylite assemblages

Sherlock, S.C.; Watts, L.M.; Holdsworth, R.E. and Roberts, D. (2004). Dating fault reactivation by Ar/Ar laserprobe: an alternative view of apparently cogenetic mylonite–pseudotachylite assemblages. Journal of the Geological Society, 161(3) pp. 335–338.

DOI: https://doi.org/10.1144/0016-764903-160

URL: http://www.ingentaconnect.com/content/geol/jgs/200...

Abstract

Apparently cogenetic mylonite–pseudotachylite assemblages are commonly reported in major fault zones. They represent two very incompatible modes of deformation, and complex formation mechanisms have been proposed to explain this paradox. We report here one such assemblage from Central Norway in which apparently synchronous mylonite and pseudotachylite formation is separated by 100 Ma-mean muscovite Ar/Ar laserprobe spot ages from mylonite, and pseudotachylite matrix, are 406 ± 11 Ma and 290 ± 10 Ma respectively. In preference to a complex cogenetic model we invoke fault reactivation as a viable alternative, and suggest that assumed contemporaneity in such assemblages may be invalid in many cases.

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• Item ORO ID
• 2239
• Item Type
• Journal Item
• ISSN
• 0016-7649
• Extra Information
• Some of the symbols may not have transferred correctly into this bibliographic record and/or abstract.
• Keywords
• Ar-Ar; argon geochronology; pseudotachylite; mylonite; reactivation; Møre–Trøndelag Fault Complex
• Academic Unit or School
• Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
  Faculty of Science, Technology, Engineering and Mathematics (STEM)
• Depositing User
• Sarah Sherlock