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

Joseph P. Gonzalez, Suzanne L. Baldwin

Research output: Contribution to journalArticle

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 40 Ar/ 39 Ar 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 40 Ar* resides within multiple diffusion domains with varying 40 Ar* 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 40 Ar/ 39 Ar 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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