Open AccessChemistry of hydrothermal plumes above submarine volcanoes of the Mariana Arc
Author(s) -
Resing Joseph A.,
Baker Edward T.,
Lupton John E.,
Walker Sharon L.,
Butterfield David A.,
Massoth Gary J.,
Nakamura Koichi
Publication year - 2009
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2008gc002141
Subject(s) - hydrothermal circulation , volcano , geology , hydrothermal vent , alkalinity , submarine volcano , geochemistry , chemical composition , mantle (geology) , earth science , mineralogy , seismology , chemistry , organic chemistry
Fifty submarine volcanoes of the Mariana Arc, covering 1200 km from 13.5°N to 23.2°N, were surveyed for hydrothermal activity. Of these 50 volcanoes, eight showed limited evidence of hydrothermal activity, while another 10 volcanoes displayed intense, chemically rich, hydrothermal plumes that allow detailed chemical characterization and insight into the hydrothermal activity forming the fluids that generate the plumes. The most active volcanoes exhibit a wide range of CO 2 to pH relationships, from the venting of acid‐rich fluids, to CO 2 ‐rich fluids, to fluids rich in alkalinity and CO 2 . These pH‐CO 2 ‐alkalinity relationships are partially responsible for the wide range of Fe:Mn (3 to 32) observed at the different volcanoes. This chemical heterogeneity is further manifest in a wide range of CO 2 : 3 He (3 × 10 9 to 55 × 10 9 ), indicating that for all but one, >80% of the CO 2 venting from these volcanoes has a slab source. The helium, by contrast, has an upper mantle isotopic signature. The range of chemical conditions suggests that these volcanoes occupy various states of eruptive evolution ranging from ongoing magmatic activity to highly evolved hydrothermal systems.