meltPT: A Python package for basaltic whole-rock thermobarometric analysis with application to Hawai‘i

Abstract

Quantifying the depths and temperatures from which igneous rocks are derived is an important step in understanding volcanic, magmatic and mantle processes. We present meltPT, a Python package that allows users to apply twelve published whole-rock thermobarometers within a consistent framework, as well as combine thermobarometric results and geothermal models to estimate mantle potential temperatures. We apply meltPT to basaltic rocks from mid-ocean ridges and the Hawaiian Islands. We find that mid-ocean ridge basalts equilibrate between 1–2 GPa and 1275–1475 °C, corresponding to an ambient mantle potential temperature of ~1400 °C. We estimate that the Hawaiian plume has an excess temperature of ~150 °C. Hawaiian melt-equilibration depths increase from 1–3 GPa to 2.5–5 GPa through each island’s life cycle. Our results indicate that multiple lithologies are present within the plume, and that transient plume reconfiguration in response to changing plate velocity is a viable mechanism for generating Hawai‘i’s two geochemically distinct plume tracks.