A new clinopyroxene thermobarometer for mafic to intermediate magmatic systems
<p>Clinopyroxene-only thermobarometry is one of the most practical tools to reconstruct crystallization pressures and temperatures of clinopyroxenes. Because it does not require any information of coexisting silicate melt or other co-crystallized mineral phases, it has been widely used to eluc...
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-10-01
|
| Series: | European Journal of Mineralogy |
| Online Access: | https://ejm.copernicus.org/articles/33/621/2021/ejm-33-621-2021.pdf |
| Summary: | <p>Clinopyroxene-only thermobarometry is one of the most
practical tools to reconstruct crystallization pressures and temperatures of
clinopyroxenes. Because it does not require any information of coexisting
silicate melt or other co-crystallized mineral phases, it has been widely
used to elucidate the physiochemical conditions of crystallizing magmas.
However, previously calibrated clinopyroxene-only thermobarometers display
low accuracy when being applied to mafic and intermediate magmatic systems.
Hence, in this study, we present new empirical nonlinear barometric and
thermometric models, which were formulated to improve the performance of
clinopyroxene-only thermobarometry. Particularly, a total of 559
experimental runs conducted in the pressure range of 1 bar to 12 kbar have been used for calibration and validation of the new barometric and
thermometric formulation. The superiority of our new models with respect to
previous ones was confirmed by comparing their performance on 100
replications of calibration and validation, and the standard error of
estimate (SEE) of the new barometer and thermometer are 1.66 kbar and
36.6 <span class="inline-formula"><sup>∘</sup></span>C, respectively. Although our new barometer and thermometer fail to reproduce the entire test dataset, which has not been used for
calibration and validation, they still perform well on clinopyroxenes
crystallized from subalkaline basic to intermediate magmas (i.e., basaltic,
basalt-andesitic, dacitic magma systems). Thus, their applicability should
be limited to basaltic, basalt-andesitic and dacitic magma systems. In a
last step, we applied our new thermobarometer to several tholeiitic
Icelandic eruptions and established magma storage conditions exhibiting a
general consistency with phase equilibria experiments. Therefore, we propose that our new thermobarometer represents a powerful tool to reveal the crystallization conditions of clinopyroxene in mafic to intermediate magmas.</p> |
|---|---|
| ISSN: | 0935-1221 1617-4011 |