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Experimental studies on New Zealand hot spring sinters; rates of growth and textural development

B. W. Mountain, L. G. Benning and J. A. Boerema
Experimental studies on New Zealand hot spring sinters; rates of growth and textural development (in Sedimentology of hot spring systems--Sedimentologie des sources thermales, Brian Jones (editor) and Robin W. Renaut (editor))
Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre (November 2003) 40 (11): 1643-1667

Abstract

To study the rate of growth of sinters in New Zealand hot springs, field experiments were conducted in seven geothermal areas. At Wairakei, fan-shaped subaqueous deposits of amorphous silica grow rapidly (350 kg a (super -1) m (super -2) of drain wall) and are composed of silicified filaments with subordinate bacillus and spirillium-shaped organisms. Characterization of bacteria revealed isolates sharing >97% 16S rRNA gene sequence homologies affiliated with Thermus, Meiothermus, Bacillus, Tepidomonas, Thermomonas, Porphyrobacter, Thermonema, and, Hydrogenophilus spp., as well as previously uncultured bacteria. At Rotokawa, microstromatolites have a slow growth rate (0.004 mm day (super -1) ) that is attributed to low pH, capillary rise, and evaporation. At Champagne Pool, sinter growth (0.023 mm day (super -1) ) is dominated by wave action building alternating microbe-rich and microbe-poor layers. Silica sinter was not observed at Waikite, where slides developed a layer of calcite (0.026 mm day (super -1) ). Sinter growth at Ngatamariki (0.016 mm day (super -1) ) forms by capillary rise, evaporation, and diffusion and at Tokaanu, subaqueous growth is slow (0.002 mm day (super -1) ) and contains silicified microbes. Textures at Orakei Korako indicate similar mechanisms to Ngatamariki, except that growth is more rapid (0.023 mm day (super -1) ) due to a splash contribution. Silica and calcite saturation indices adequately explain the growth of the sinters and calcite, indicating that microbes are not inducing precipitation where it should not occur. The rate of precipitation is correlated with silica supersaturation, but pH effects can alter this relationship. The degree of preservation of microbial material is explained by the effect of Ostwald ripening on silica spherules. Subaqueous growth allows coarsening of spherules and poor preservation of smaller microbes while subaerial nucleation is rapid, Ostwald ripening is inactive, and better preservation can be expected.


ISSN: 0008-4077
EISSN: 1480-3313
Coden: CJESAP
Serial Title: Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre
Serial Volume: 40
Serial Issue: 11
Title: Experimental studies on New Zealand hot spring sinters; rates of growth and textural development
Title: Sedimentology of hot spring systems--Sedimentologie des sources thermales
Author(s): Mountain, B. W.Benning, L. G.Boerema, J. A.
Author(s): Jones, Brianeditor
Author(s): Renaut, Robin W.editor
Affiliation: Institute of Geological and Nuclear Sciences, Wairakei Research Centre, Taupo, New Zealand
Affiliation: University of Alberta, Department of Earth and Atmosphere Sciences, Edmonton, AB, Canada
Pages: 1643-1667
Published: 200311
Text Language: English
Summary Language: French
Publisher: National Research Council of Canada, Ottawa, ON, Canada
Meeting name: Geological Association of Canada-Mineralogical Association of Canada annual meeting , special session on Sedimentology of hot spring systems
Meeting location: Saskatoon, SK, CAN, Canada
Meeting date: 200205May 2002
References: 56
Accession Number: 2004-026442
Categories: Sedimentary petrology
Document Type: Serial Conference document
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, sketch map
S39°04'60" - S38°00'00", E175°30'00" - E177°10'00"
Secondary Affiliation: University of Saskatchewan, CAN, CanadaUniversity of Leeds, GBR, United KingdomHorticulture and Food Research Institute of New Zealand, NZL, New Zealand
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 200408
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