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|Title:||Unusual mixed silica-carbonate deposits from magmatic-hydrothermal hot springs, Savo, Solomon Islands|
|Authors:||Smith, Daniel J.|
|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.|
|Rights:||Journal of record JOURNAL OF THE GEOLOGICAL SOCIETY, 2011, 168 (6), pp. 1297-1310 http://jgs.lyellcollection.org/content/168/6/1297 Copyright 2011 Geological Society of London 2011.|
|Appears in Collections:||Published Articles, Dept. of Geology|
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