Experimental calibration of an Fe3+/Fe2+-in-amphibole oxybarometer and its application to shallow magmatic processes at Shiveluch Volcano, Kamchatka

Researchers developed an amphibole oxybarometer to measure oxygen fugacity (fO2) in arc magmas, revealing that primitive melts at Shiveluch Volcano, Kamchatka, have an fO2 of approximately NNO+2. This method, calibrated experimentally, shows that amphibole faithfully records magmatic fO2 but may also reflect partial dehydrogenation during shallow storage. The study identifies multiple pulses of mafic magma recharge before eruptions and suggests complex shallow magmatic processes involving at least two magmas at varying differentiation stages.

Goltz, A. E., Krawczynski, M. J., McCanta, M. C., & Dyar, M. D. (2022). Experimental calibration of an Fe3+/Fe2+-in-amphibole oxybarometer and its application to shallow magmatic processes at Shiveluch Volcano, Kamchatka. American Mineralogist, 107(11), 2084–2100. https://doi.org/10.2138/am-2022-8031