Hydrogen, oxygen and sulfur isotope studies of seafloor hydrothermal system at the Desmos Caldera, Manus back-arc basin, Papua New Guinea; an analogue of terrestrial acid hot crater-lake

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doi: 10.1111/j.1751-3928.2006.tb00278.x
Authors:Gena, Kaul R.; Chiba, Hitoshi; Mizuta, Toshio; Matsubaya, Osamu
Author Affiliations:Primary:
Okayama University, Faculty of Science, Department of Earth Science, Okayama, Japan
Other:
Akita University, Japan
Volume Title:Resource Geology (Tokyo. 1998)
Source:Resource Geology (Tokyo. 1998), 56(2), p.183-190. Publisher: Wiley-Blackwell on behalf of the Society of Resource Geology, Oxford, United Kingdom. ISSN: 1344-1698
Publication Date:2006
Note:In English. 39 refs.; illus., incl. 1 table, geol. sketch map
Summary:The hydrothermal fluid at the Onsen site, an active submarine hydrothermal system hosted by the Desmos caldera in the Eastern Manus Basin, Papua New Guinea, is very acidic with pH =1.5. Abundant native sulphur is deposited around the vent. The δ34S values of native sulphur range from -6.5 to -9.30/00. The δ34S values of H2S and SO4 in the hydrothermal fluid are -4.3 to -9.90/00 and +18.6 to +20.00/00, respectively. The δ34S values are significantly lower than those of hydrothermal systems so far reported. The low δ34S values and the acidic nature suggest that volcanic SO2 gas plays an important role on the sulphur isotope systematics. The characteristic can be explained by the model based on the disproportionation reaction starting from the volcanic SO2 gas. The predicted δ34S values of SO2 agree with the measured whole rock δ34S values. δD and δ18O values of clay minerals separated from the altered rock samples also suggest the contribution of the magmatic fluid to the hydrothermal system. From these data it is suggested that the Onsen hydrothermal site is a magmatic submarine hydrothermal system. [I.S.]
Sections:Geochemistry
Subsections:Hydrogeochemistry
Subjects:Acidic composition; Back-arc basins; Basins; Clay minerals; Gases; Geothermal systems; Hydrogen; Hydrothermal conditions; Hydrothermal vents; Isotope ratios; Isotopes; Native elements; Ocean floors; Oxygen; PH; S-34/S-32; Sheet silicates; Silicates; Stable isotopes; Sulfur; Sulfur dioxide; Australasia; Bismarck Sea; Manus Basin; Pacific Ocean; Papua New Guinea; South Pacific; Southwest Pacific; West Pacific; Acid-sulfate alteration; Desmos Caldera; Onsen hydrothermal site
Coordinates:S042000 S042000 E1514000 E1514000
Abstract Numbers:08M/0882
Record ID:2016019999
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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