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Title: Unusual mixed silica-carbonate deposits from magmatic-hydrothermal hot springs, Savo, Solomon Islands
Authors: Smith, Daniel J.
Jenkin, GRT
Petterson, MG
Fielder, S
Naden, J
Chenery, SRN
Toba, T
First Published: Dec-2011
Publisher: Geological Society
Citation: JOURNAL OF THE GEOLOGICAL SOCIETY, 2011, 168 (6), pp. 1297-1310
Abstract: The volcanic island of Savo, Solomon Islands, hosts an active hydrothermal system discharging unusual alkaline (pH 7–8) sulphate-rich, chloride-poor fluid, with variable admixtures of Ca–Mg–HCO3−-rich fluid. Hot springs and their outflow streams precipitate a variety of deposits, including travertine, silica sinter and unusual mixed silica–carbonate rocks. Travertine fabrics are dominated by ray-crystal calcite, associated with rapid abiotic precipitation from a supersaturated solution. Sinter is produced by evaporation of thermal waters, and downstream samples contain preserved traces of micro-organisms, which potentially acted as templates for precipitation. Trace element chemistry of sinters and travertines includes anomalously high levels of Te, indicating a magmatic origin for a component fluid in the hydrothermal system. Springs are close to or at saturation with both calcite and amorphous silica. Increased contributions from the Ca–Mg–HCO3− end-member favours calcite formation; this fluid is of low-temperature origin, and as such is favoured by high rainfall. Mixed samples show cyclical changes between silica and carbonate precipitation, potentially as a result of seasonal variation in rainfall.
DOI Link: 10.1144/0016-76492011-003
ISSN: 0016-7649
eISSN: 2041-479X
Type: Journal Article
Rights: Journal of record JOURNAL OF THE GEOLOGICAL SOCIETY, 2011, 168 (6), pp. 1297-1310 Copyright 2011 Geological Society of London 2011.
Appears in Collections:Published Articles, Dept. of Geology

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