O-C[O.sub.2] solubility in mafic alkaline magma: applications to volatile sources and degassing behavior at Erebus volcano, Antarctica

• Published in: Contributions to mineralogy and petrology Vol. 166; no. 3; p. 845
• Main Authors: Iacovino, Kayla, Moore, Gordon, Roggensack, Kurt, Oppenheimer, Clive, Kyle, Philip
• Format: Journal Article
• Language: English
• Published: Springer 01.09.2013
• Subjects: Infrared spectroscopy; Volcanoes
• ISSN: 0010-7999; 1432-0967
• DOI: 10.1007/s00410-013-0877-2

We present new equilibrium mixed-volatile ([H.sub.2]O-C[O.sub.2]) solubility data for a phonotephrite from Erebus volcano, Antarctica. [H.sub.2]O-C[O.sub.2]-saturated experiments were conducted at 400-700 MPa, 1,190°C, and ~ NNO + 1 in non-end-loaded piston cylinders. Equilibrium [H.sub.2]O-C[O.sub.2] fluid compositions were determined using low-temperature vacuum manometry, and the volatile and major element compositions of the glassy run products were determined by Fourier transform infrared spectroscopy and electron microprobe. Results show that the phonotephrite used in this study will dissolve ~ 0.8 wt% C[O.sub.2] at 700 MPa and a fluid composition of [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], in agreement with previous experimental studies on mafic alkaline rocks. Furthermore, the dissolution of C[O.sub.2] at moderate to high [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] in our experiments exceeds that predicted using lower-pressure experiments on similar melts from the literature, suggesting a departure from Henrian behavior of volatiles in the melt at pressures above 400 MPa. With these data, we place new constraints on the modeling of Erebus melt inclusion and gas emission data and thus the interpretation of its magma plumbing system and the contributions of primitive magmas to passive and explosive degassing from the Erebus phonolite lava lake.