Barometers behaving badly: Assessing the influence of analytical and experimental uncertainty on clinopyroxene thermobarometry calculations at crustal conditions

Journal of Petrology
By: , and 

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Abstract

The composition of clinopyroxene and clinopyroxene-liquid (Cpx-Liq) pairs are frequently used to calculate crystallization/equilibration pressures in igneous systems. While canonical uncertainties are often assigned to calculated pressures based on fits to calibration or test datasets, the sources of these uncertainties (and thus ways to reduce them) have not been rigorously assessed. We show that considerable uncertainties in calculated pressures arise from analytical error associated with Electron Probe Microanalyser (EPMA) measurements of Cpx. Specifically, low X-ray counts during analysis of elements with concentrations <1 wt% resulting from insufficient count times and/or low beam currents yield highly imprecise measurements (1σ errors of 10–40% for Na2O).

Publication type Article
Publication Subtype Journal Article
Title Barometers behaving badly: Assessing the influence of analytical and experimental uncertainty on clinopyroxene thermobarometry calculations at crustal conditions
Series title Journal of Petrology
DOI 10.1093/petrology/egac126
Volume 64
Issue 2
Year Published 2023
Language English
Publisher Oxford Academic
Contributing office(s) Volcano Science Center
Description egac126, 27 p.
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