%0 Generic %A Smith, D.J. %A Jenkin, G.R.T. %A Petterson, M.G. %A Naden, J. %A Fielder, S. %A Toba, T. %A Chenery, S.R.N. %D 2016 %T Unusual mixed silica–carbonate deposits from magmatic–hydrothermal hot springs, Savo, Solomon Islands %U https://geolsoc.figshare.com/articles/dataset/Unusual_mixed_silica_carbonate_deposits_from_magmatic_hydrothermal_hot_springs_Savo_Solomon_Islands/3452966 %R 10.6084/m9.figshare.3452966.v1 %2 https://geolsoc.figshare.com/ndownloader/files/5421074 %2 https://geolsoc.figshare.com/ndownloader/files/5421077 %2 https://geolsoc.figshare.com/ndownloader/files/5421080 %K hydrothermal system %K sinter %K fluid %K Solomon Islands %K Mixed samples show %K Savo %K calcite %K origin %K rainfall %K travertine %K trace element chemistry %K magmatic %K Geology %X

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.

%I Geological Society of London