Modelling white mica pressure-temperature-time (P-T-t) paths using thermobarometric and 40Ar/39Ar thermochronologic data

Joseph P. Gonzalez, Suzanne L. Baldwin

Research output: Contribution to journalArticlepeer-review

Abstract

White micas are major rock forming minerals in igneous and metamorphic rocks, and their chemical and isotopic variations can be used to determine pressure, temperature and time (P-T-t) histories. We apply 40Ar/39Ar multi-diffusion domain modelling to white micas from blueschists blocks in serpentinite matrix mélange from the exhumed Baja California subduction complex. Thermal history models yielded T-t paths suggesting that 40Ar* resides within multiple diffusion domains with varying 40Ar* retentivity. Modelled white mica thermal histories and thermobarometric data were used to forward model continuous P-T-t paths. P-T-t paths are consistent with previous studies and are interpreted to constrain blueschist block exhumation paths within the Baja accretionary wedge. Our P-T-t models use temperature controlled 40Ar/39Ar step heat data in which argon loss by volume diffusion can be demonstrated, and for which the white mica petrogenesis is known.

Original languageEnglish (US)
Pages (from-to)169-178
Number of pages10
JournalTerra Nova
Volume31
Issue number3
DOIs
StatePublished - Jun 2019

Keywords

  • Ar/Ar age gradients
  • P-T-t paths
  • diffusion
  • thermal history modelling
  • thermobarometry
  • white mica

ASJC Scopus subject areas

  • Geology

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