Hydrothermal Alteration in Active Geothermal Fields

Browne, P. R. L.

doi:10.1146/annurev.ea.06.050178.001305

Cited by 501 publications

(242 citation statements)

References 28 publications

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“…A low-temperature environment (<120°C), is characterised by those samples dominated by palagonite alteration, as well as sulphate, iron oxide, and smectite secondary alteration products (Stroncik & Schmincke 2002). This is typical as basaltic glass easily alters to opal, smecitite, zeolites, and clays (Browne 1978). Askja samples ASK03, ASK04, ASK07, ASK09, and fissure swarm sample KV07 fall within this range.…”

Section: Fingerprint For Environmental Conditionsmentioning

confidence: 96%

“…This could represent a stage of initial high temperature alteration (Kristmannsdottir & Tomasson 1978;Franzson 2000), resulting in extensive alteration of basaltic glass to heulandite and smectite, followed by lower-temperature alteration allowing the formation of sulfates such as gypsum and jarosite. Higher temperature minerals such as chlorite (>230°C), epidote (>260°C), and amphibole (>280°C) (Browne 1978) are not identified. Figure 21 summarises the temperature ranges for these two thermal environments and the associated alteration minerals.…”

Section: Fingerprint For Environmental Conditionsmentioning

confidence: 99%

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Glaciovolcanic hydrothermal environments in Iceland and implications for their detection on Mars

Cousins

Crawford

Carrivick

et al. 2013

Journal of Volcanology and Geothermal Research

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Hydrothermal environments driven by volcanism are prime astrobiological targets on Mars, due to their ability to support and preserve microbial ecosystems. Volcano -ice interactions on On Earth, volcano -ice interactions produce many hydrothermal habitats available to microbial colonisation, and thus provide an analogue to past environments on Mars, where many landforms have been attributed to volcano -cryospheric interaction. However, Mars exploration urgently requires a framework for identifying such environments on a range of scales and with a range of geological criteria. In this paper rRemote sensing data were combined with sub-mm environmental mapping and sample analysis that included (X-ray diffraction, Raman spectroscopy, thin section petrography, scanning electron microscopy, electron dispersive spectrometer analysis, and dissolved ion water chemistry,) to characterise samples from two areas of basaltic volcano -ice interaction: namely Askja and Kverkfjöll volcanoes in Iceland. Askja was erupted subglacially during the Pleistocene, and is now exposed within a volcanic desert. Kverkfjöll is a subglacial volcano beneath on the northern margin of Vatnajökull ice cap, and hosts active hydrothermal systems. NE-trending fissure swarm ridges extend between these two volcanic systems. Multiple Holocene glacial outburst (jökulhlaup) sedimentary deposits lie to the north of Kverkfjöll. Hydrothermal environments at Kverkfjöll were found to be predominantly acidic, with dissolved sulphate dominating the water chemistry. These hydrothermal environments vary across a small (<100 m) spatial scale, and include hot springs, anoxic pools, meltwater lakes, and sulphur-and iron-depositing fumaroles. Biomats, two in association with individual goethite and pyrite mineral terraces, were common at Kverkfjöll. In-situ and laboratory VNIR (440 -1000 nm) reflectance spectra representative of Mars rover multispectral imaging show spectral profiles to be influenced by Fe 2+/3+ -bearing minerals. Overall, sediments and lavas display two types of hydrothermal alteration: a low-temperature (<120°C) assemblage dominated by palagonite, sulfates, and iron oxides; and a high-temperature (>120°C) assemblage signified by heulandite and quartz. This Overall, this work provides a framework for identifying such environments during future exploration of Mars, given their high astrobiological potential, and Claire Cousins -BBK 14/08/12 3 provides a descriptive reference for the two prominent active hydrothermal environments at Kverkfjöllwhich can be used as analogues for those on Mars.

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Section: Fingerprint For Environmental Conditionsmentioning

confidence: 96%

Section: Fingerprint For Environmental Conditionsmentioning

confidence: 99%

Glaciovolcanic hydrothermal environments in Iceland and implications for their detection on Mars

Cousins

Crawford

Carrivick

et al. 2013

Journal of Volcanology and Geothermal Research

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“…Zeolites occur f n v i r t u a l l y every major geothernal system i n the world I n a d d i t i o n t o the more common phases (heulandite, laumontite, and w a i r a k i t e ) , other calcium z e o l i t e s which have been reported from a c t i v e geothermal systems include s t i l b i t e , chabazite , thomsonite, scolecite, mordenite, yugawaral i t e , levyne , gismondine , and gmel i n i t e (Browne , 1978;Kristmannsdottir and Tomasson, 1976) .…”

Section: Cal C I Um Zeol I T E Smentioning

confidence: 99%

Calc-silicate mineralization in active geothermal systems

Bird¹,

Schiffman²,

Elders³

et al. 1984

Economic Geology

201

104

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“…In the Purisima-Colon vein system (Pachuca, Mexico), base metals are concentrated at depth, and there is an intermediate-depth zone with high Ag grades overlapping the base metal zone (Dreier, 2005). The presence of adularia, bladed calcite, and coexisting liquid-rich and vapour-rich inclusions are evidence of local boiling (Browne & Ellis, 1970;Browne, 1978;Hedenquist et al, 2000;Simmons & Browne, 2000). Plotting of Pb, Zn and Au against depth in Au-bearing quartz veins shows that these elements have similar behaviours.…”

Section: Discussionmentioning

confidence: 99%

Geochemistry and statistical analyses of porphyry system and epithermal veins at Hizehjan in northwestern Iran

et al. 2017

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Situated about 130 km northeast of Tabriz (northwest Iran), the Mazra’eh Shadi deposit is in the Arasbaran metallogenic belt (AAB). Intrusion of subvolcanic rocks, such as quartz monzodiorite-diorite porphyry, into Eocene volcanic and volcano-sedimentary units led to mineralisation and alteration. Mineralisation can be subdivided into a porphyry system and Au-bearing quartz veins within andesite and trachyandesite which is controlled by fault distribution. Rock samples from quartz veins show maximum values of Au (17100 ppb), Pb (21100 ppm), Ag (9.43ppm), Cu (611ppm) and Zn (333 ppm). Au is strongly correlated with Ag, Zn and Pb. In the Au-bearing quartz veins, factor group 1 indicates a strong correlation between Au, Pb, Ag, Zn and W. Factor group 2 indicates a correlation between Cu, Te, Sb and Zn, while factor group 3 comprises Mo and As. Based on Spearman correlation coefficients, Sb and Te can be very good indicator minerals for Au, Ag and Pb epithermal mineralisation in the study area. The zoning pattern shows clearly that base metals, such as Cu, Pb, Zn and Mo, occur at the deepest levels, whereas Au and Ag are found at higher elevations than base metals in boreholes in northern Mazra’eh Shadi. This observation contrasts with the typical zoning pattern caused by boiling in epithermal veins. At Mazra’eh Shadi, quartz veins containing co-existing liquid-rich and vapour-rich inclusions, as strong evidence of boiling during hydrothermal evolution, have relatively high Au grades (up to 813 ppb). In the quartz veins, Au is strongly correlated with Ag, and these elements are in the same group with Fe and S. Mineralisation of Au and Ag is a result of pyrite precipitation, boiling of hydrothermal fluids and a pH decrease.

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Hydrothermal Alteration in Active Geothermal Fields

Cited by 501 publications

References 28 publications

Glaciovolcanic hydrothermal environments in Iceland and implications for their detection on Mars

Glaciovolcanic hydrothermal environments in Iceland and implications for their detection on Mars

Calc-silicate mineralization in active geothermal systems

Geochemistry and statistical analyses of porphyry system and epithermal veins at Hizehjan in northwestern Iran

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