Thermobar: An open-source Python3 tool for thermobarometry and hygrometry

Wieser, Penny; Petrelli, Maurizio; Lubbers, Jordan; Wieser, Eric; Özaydın, Sinan; Kent, Adam J.R.; Till, C. B.

doi:10.30909/vol.05.02.349384

Cited by 42 publications

(38 citation statements)

References 95 publications

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“…We filter out Amp with cation sums outside of 15–16. All thermobarometry and filtering calculations were performed using the open‐source Python3 tool Thermobar (Wieser et al., 2022c).…”

Section: Mineral Barometrymentioning

confidence: 99%

Geophysical and Geochemical Constraints on Magma Storage Depths Along the Cascade Arc: Knowns and Unknowns

Wieser,

Kent,

Till

et al. 2023

Geochem Geophys Geosyst

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The iconic volcanoes of the Cascade arc stretch from Lassen Volcanic Center in northern California, through Oregon and Washington, to the Garibaldi Volcanic Belt in British Columbia. Recent studies have reviewed differences in the distribution and eruptive volumes of vents, as well as variations in geochemical compositions and heat flux along strike (amongst other characteristics). We investigate whether these along‐arc trends manifest as variations in magma storage conditions. We compile available constraints on magma storage depths from InSAR, geodetics, seismic inversions, and magnetotellurics for each major edifice and compare these to melt inclusion saturation pressures, pressures calculated using mineral‐only barometers, and constraints from experimental petrology. The availability of magma storage depth estimates varies greatly along the arc, with abundant geochemical and geophysical data available for some systems (e.g., Lassen Volcanic Center, Mount St. Helens) and very limited data available for other volcanoes, including many which are classified as “very high threat” by the USGS (e.g., Glacier Peak, Mount Baker, Mount Hood, Three Sisters). Acknowledging the limitations of data availability and the large uncertainties associated with certain methods, available data are indicative of magma storage within the upper 15 km of the crust (∼2 ± 2 kbar) beneath the main edifices. These findings are consistent with previous work recognizing barometric estimates cluster within the upper crust in many arcs worldwide. There are no clear offsets in magma storage between arc segments that are in extension, transtension or compression, although substantially more petrological work is needed for fine scale evaluation of storage pressures.

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“…We filter out Amp with cation sums outside of 15–16. All thermobarometry and filtering calculations were performed using the open‐source Python3 tool Thermobar (Wieser et al., 2022c).…”

Section: Mineral Barometrymentioning

confidence: 99%

Geophysical and Geochemical Constraints on Magma Storage Depths Along the Cascade Arc: Knowns and Unknowns

Wieser,

Kent,

Till

et al. 2023

Geochem Geophys Geosyst

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“…We calculate the proportion of Fe 2+ in each experiment using the experimental fO2 or quoted buffer position and the experimental pressure and temperature, with the equations of Kress and Carmichael (1988) implemented in Thermobar (an open-source Python-based thermobarometry tool, Wieser et al, 2022b). For completeness, although stoichiometric methods estimating Fe 2+ in minerals are associated with large errors, we also calculate Fe 2+ in the Cpx using the method of (Lindsley, 1983), and calculate KD using just Fe 2+ in both phases.…”

Section: Equilibrium Testsmentioning

confidence: 99%

“…Alternatively, if no suitable experimental data exists, insight may be gained by comparing the dataset used to calibrate each thermobarometry equation against the natural compositions of interest to evaluate the degree of extrapolation required (e.g., Wieser et al, 2022b;Wieser et al, 2022c).…”

Section: Introductionmentioning

confidence: 99%

Barometers behaving badly II: A critical evaluation of Cpx-only and Cpx-Liq thermobarometry in variably-hydrous arc magmas

Wieser¹,

Kent²,

Till³

2024

Preprint

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The chemistry of erupted clinopyroxene crystals (±equilibrium liquids) have been widely used to deduce the pressures and temperatures of magma storage in volcanic arcs. However, the wide variety of different equations parametrizing the relationship between mineral and melt compositions and intensive variables such as pressure and temperature yield vastly different results, with implications for our interpretation of magma storage conditions. We use a new test dataset of N=505 Cpx-Liq pairs from variably-hydrous experiments at crustal conditions (0-13 kbar) to assess the performance of different thermobarometers, and identify the most accurate and precise expressions for application to subduction zone magmas. First, we assess different equilibrium tests, finding that comparing the measured and predicted EnFs and KD (using Fet in both phases) are the most useful tests in arc magmas, while CaTs, CaTi and Jd tests have limited utility. We then apply further quality filters based on cation sums (3.95-4.05), number of analyses (N>5), and the presence of reported H2O data in the liquid to obtain a filtered dataset (N=194). We use this filtered dataset to compare calculated versus experimental pressures and temperatures for different combinations of thermobarometers. A number of Cpx-Liq thermometers perform very well when liquid H2O contents are known, although the Cpx composition contributes relatively little to the calculated temperature. Most Cpx-only thermometers perform very badly, greatly overestimating temperatures for hydrous experiments. Cpx-Liq and Cpx-only barometers show similar performance to one another, all showing low precision and systematic offsets (overestimating pressure for low P experiments, and underestimating pressure for High P expressions). We also assess the sensitivity of different equations to melt H2O contents, which are poorly constrained in many natural systems. Overall, this work demonstrates that substantial work is needed to obtain precise and accurate estimates of magma storage depths from Cpx±Liq equilibrium in volcanic arcs. At present, Cpx-based barometry only provides sufficient resolution to distinguish broad storage regions (e.g., upper, mid, lower crust), rather than ability to precisely and accurately locate magma reservoirs to compare to geophysical records.

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“…Building on functionality in Thermobar (Wieser et al [2022]), DiadFit can convert entrapment pressures to depths using various options (Fig. 1h):…”

Section: Converting Pressures Into Depthsmentioning

confidence: 99%

DiadFit: An Open-Source Python3 Tool for Peak fitting of Raman Data from silicate melts and CO2 fluids

Wieser¹,

DeVitre²

2024

Preprint

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We present a new Open-Source Python3 tool, DiadFit, for efficient processing of Raman spectroscopydata associated with silicate melts and CO2 fluids. DiadFit can fit Fermi diads, hot bands, 13C peaks,and Ne lines using various background and peak shapes. Thus, it is highly suited for workflows involving melt inclusion vapour bubbles and fluid inclusions (FI). We include generic peak fitting functions(e.g., for fitting carbonate and S-rich phases), and functions to quantify the area ratio of the silicate vs.H2O region of spectra collected on silicate glasses to determine H2O contents. DiadFit can convert between temperature, pressure and density using the CO2 equation of state (EOS), allowing calculation ofFI entrapment pressures (and depths in the crust) DiadFit can also calculate CO2 density from microthermometry measurements of Thomog . DiadFit can propagate errors in these EOS calculations using MonteCarlo methods. Documentation and worked examples are available (https://bit.ly/DiadFitRTD,https://bit.ly/DiadFitYouTube)

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Thermobar: An open-source Python3 tool for thermobarometry and hygrometry

Cited by 42 publications

References 95 publications

Geophysical and Geochemical Constraints on Magma Storage Depths Along the Cascade Arc: Knowns and Unknowns

Geophysical and Geochemical Constraints on Magma Storage Depths Along the Cascade Arc: Knowns and Unknowns

Barometers behaving badly II: A critical evaluation of Cpx-only and Cpx-Liq thermobarometry in variably-hydrous arc magmas

DiadFit: An Open-Source Python3 Tool for Peak fitting of Raman Data from silicate melts and CO2 fluids

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