Experimental study demonstrates oxygen fugacity estimation using pyroxene-melt vanadium-scandium exchange in arc magmas, highlighting broad applicability for magmatic redox tracking.
Key Points
To calibrate vanadium–scandium exchange oxybarometers between clinopyroxene, orthopyroxene, and silicate melt under physical and chemical conditions representative of arc magmatism.
Conducted high-pressure rapid-quench experiments at 200 MPa under water-saturated conditions (1030–870 °C, fO2 from FMQ −1 to +7) using a molybdenum-hafnium carbide pressure vessel assembly with a semi-permeable hydrogen membrane.
Evaluated melt composition effects using medium-K calc-alkaline basaltic and shoshonitic magmas combined with published experimental datasets.
The orthopyroxene-melt oxybarometer accurately reproduced fO2 with a median absolute error of 0.36 log units over the range FMQ −2 to +5.5.
The clinopyroxene-melt oxybarometer yielded a median absolute error of 1.01 log units across the calibrated range FMQ −2.5 to +5.