Determining cooling rates from mica ⁴⁰Ar/ ³⁹Ar thermochronology data: effect of cooling path shape

McDonald, Christopher S.; Warren, Clare J.; Hanke, Felix and Chard, Julian (2019). Determining cooling rates from mica ⁴⁰Ar/ ³⁹Ar thermochronology data: effect of cooling path shape. Terra Nova, 31(3) pp. 234–246.

DOI: https://doi.org/10.1111/ter.12390

Abstract

Tectonic models are commonly underpinned by metamorphic cooling rates derived fromd iffusive-loss thermochronology data. Such cooling agesare usually linked to temperature via Dodson’s 1973 closure temperature (T_C) formulation, which specifies a 1/time shaped cooling path. Geologists, however,commonly discuss cooling rates as a linear temperature/time shape. We present the results of a series of simple finite-difference diffusion models for Ar diffusion in muscovite and biotite that show that the difference in recorded age between 1/t and linear cooling paths increases significantly with hotter starting temperatures, slower cooling rates and smaller grain sizes. Our results show that it is essential to constrain the cooling path shape in order to make meaningful interpretations of the measured data.

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About

• Item ORO ID
• 60259
• Item Type
• Journal Item
• ISSN
• 1365-3121
• Extra Information
• This paper was presented at the 16th International Conference on Thermochronology (Quedlinburg, Germany, September 2018).
• Keywords
• Thermochronology; Diffusion Modelling; Closure Temperature; muscovite; biotite; 40Ar/39Ar
• Academic Unit or School
• Faculty of Science, Technology, Engineering and Mathematics (STEM) > Environment, Earth and Ecosystem Sciences
  Faculty of Science, Technology, Engineering and Mathematics (STEM)
• Copyright Holders
• © 2019 The Authors
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