Silica phases in sinters and residues from geothermal fields of New Zealand

Rodgers, K. A.; Browne, P. R. L.; Buddle, Timothy; Cook, Kristen; Greatrex, R.A.; Hampton, W. A.; Herdianita, Niniek Rina; Holland, G.R.; Lynne, Bridget Y.; Martin, Rose; Newton, Z.; Pastars, D.; Sannazarro, K.L.; Teece, C.I.A.

doi:10.1016/j.earscirev.2003.10.001

Cited by 157 publications

(145 citation statements)

References 43 publications

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“…Traces of calcite locally coat the amorphous silica, suggesting it represents a later stage in the evolution of the deposits. The SiO 2 maturation sequence observed at Coso is closely follows the changes observed in sinter deposits (Rodgers et al, 2004;Lynne and Campbell (2004).…”

Section: Occurrence Of Scale Deposits Within the Reservoir Rockssupporting

confidence: 52%

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Geochemical Enhancement Of Enhanced Geothermal System Reservoirs: An Integrated Field And Geochemical Approach

Moore¹

2007

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The proposed work plan for this project is shown in Figure 1. The project was funded through year 2 and was successful in meeting its objectives to that point. During the second year of the project, DOE requested that Dr. Moore provide additional support to the Coso EGS program and the objectives of the project were modified. At the time the project was terminated at the end of year 2, the objectives of the project were to:

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Section: Occurrence Of Scale Deposits Within the Reservoir Rockssupporting

confidence: 52%

“…5d). Similar features, interpreted as silicified bacteria, have been observed in sinters from New Zealand (Rodgers et al, 2004).…”

Section: Occurrence Of Scale Deposits Within the Reservoir Rockssupporting

confidence: 49%

Geochemical Enhancement Of Enhanced Geothermal System Reservoirs: An Integrated Field And Geochemical Approach

Moore¹

2007

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“…Such environments are highly analogous and indeed inseparable from the high-sulfidation environments responsible for some types of epithermal ore formation (Henley and McNabb, 1978;Hedenquist et al, 1998;Berger et al, 2014). In the most acid-altered areas, the dominant material is various forms of silica (Hemley and Jones, 1964;Henley and McNabb, 1978;Delmelle et al, 2015), which may convert with time from amorphous silica (opal-A) to more crystalline forms of silica, including opal-CT, opal-C, chalcedony and quartz (Rodgers et al, 2004). Other minerals may include alunite, anatase, and kaolinite.…”

Section: Introductionmentioning

confidence: 99%

“…Often termed "vuggy quartz" or "vuggy silica" rocks when exposed after uplift and erosion, they presumably originate from protracted water-rock reaction where residual silica remains, with or without associated sulfates such as alunite and barite (Hedenquist and Taran, 2013). Amorphous silica can also form during decompression and quenching of hot hydrous fluids in magmatic and hydrothermal environments at temperatures up to 400 • C (Williamson et al, 2002;Tanner et al, 2015) or during cooling of silica-saturated waters in hot-spring environments (Fournier and Rowe, 1966;Rodgers et al, 2004). Occasionally, acid-altered rocks bearing amorphous silica are expelled directly from the subvolcanic environment during phreatomagmatic eruptions (Christenson and Wood, 1993;Wood, 1994;Christenson et al, 2010;van Hinsberg et al, 2010a;Mayer et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Opal-A in Glassy Pumice, Acid Alteration, and the 1817 Phreatomagmatic Eruption at Kawah Ijen (Java), Indonesia

et al. 2018

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At Kawah Ijen (Indonesia), vigorous SO 2 and HCl degassing sustains a hyperacid lake (pH ∼0) and intensely alters the subsurface, producing widespread residual silica and advanced argillic alteration products. In 1817, a VEI 2 phreatomagmatic eruption evacuated the lake, depositing a widespread layer of muddy ash fall, and sending lahars down river drainages. We discovered multiple types of opaline silica in juvenile low-silica dacite pumice and in particles within co-erupted laharic sediments. Most spectacular are opal-replaced phenocrysts of plagioclase and pyroxene adjacent to pristine matrix glass and melt inclusions. Opal-bearing pumice has been found at numerous sites, including where post-eruption infiltration of acid water is unlikely. Through detailed analyses of an initial sampling of 1817 eruption products, we find evidence for multiple origins of opaline materials in pumice and laharic sediments. Evidently, magma encountered acid-altered materials in the subsurface and triggered phreatomagmatic eruptions. Syn-eruptive incorporation of opal-alunite clasts, layered opal, and fragment-filled vesicles of opal and glass, all suggest magma-rock interactions in concert with vesiculation, followed by cooling within minutes. Our experiments at magmatic temperature confirm that the opaline materials would show noticeable degradation in time periods longer than a few tens of minutes. Some glassy laharic sedimentary grains are more andesitic than the main pumice type and may represent older volcanic materials that were altered beneath the lake bottom and were forcefully ejected during the 1817 eruption. A post-eruptive origin remains likely for most of the opal-replaced phenocrysts in pumice. Experiments at 25 • C and 100 • C reveal that when fresh pumice is bathed in Kawah Ijen hyperacid fluid for 6 weeks, plagioclase is replaced without altering either matrix glass or melt inclusions. Moreover, lack of evidence for high-temperature annealing of the opal suggests that post-eruption alteration of pumice is more likely than pre-eruption envelopment of Lowenstern et al. Opal in Glassy Pumice euhedral opal-replaced phenocrysts in dacitic melt. At Ijen and elsewhere, the ascent of magma into hydrous acid-altered mineral assemblages (e.g., opal, kaolinite, alunite) could induce rapid dehydration of hydrous minerals and amorphous materials, generating considerable steam and contributing to magmatic-hydrothermal and phreatomagmatic explosions.

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“…Teniendo en cuenta la juventud de este depósito hidrotermal dado que afecta a las lavas de 1730-1736 (Carmona et al, 2008), y que no procedan de otros basaltos profundos afectados por los mismos procesos y arrastrados por los nuevos aportes magmáticos, sugeriría un proceso mineralizador de menos de 300 años, demasiado corto para producir las transformaciones del ópalo-A a otras formas de la sílice donde al menos 10.000 años de duración son requeridos para la aparición de ópalo CT y más de 50.000 para el cuarzo microcristalino (Rodgers et al, 2004), aunque si la intensidad de flujo es suficiente estos periodos pueden ser reducidos notablemente. Pese a que estos procesos de transformación pueden acelerarse en función de las condiciones y la efectividad de circulación de los fluidos, las características textuales del ópalo de tipo esferas aisladas y en agregados sugiere que correspondan a la primera fase opalina, tal y como se observa en otros sinter modernos compuestos exclusivamente por ópalo-A: Orakei Korako (Smith et al, 2003) y Whakarewarewa (Jones & Renaut, 2004), ambas en la zona volcánica de Taupo, Nueva Zelanda.…”

Section: Procedencia De Las Muestrasunclassified

Las alteraciones silíceas de las lavas de Montaña Señalo, erupción de Timanfaya (1730-1736) (Lanzarote, Islas Canarias)

Carmona¹,

Ruiz²,

Páez³

et al. 2009

Estud. geol.

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IntroducciónPara la formación de un depósito hidrotermal, es necesario por un lado una fuente de calor y por otro una circulación eficiente de fluidos, capaces de movilizar componentes de las rocas por las que atraviesa hacia otros lugares. Si estas aguas son capaces de alcanzar la superficie y contienen la carga quími-ca suficiente, las nuevas condiciones termodinámi-cas hacen que se puedan generar depósitos y alteraciones características, identificables tanto texturalmente como en composición y contenido mineral. RESUMENLa presencia de alteraciones de origen hidrotermal entre las lavas de la erupción de Timanfaya (1730-36), con altas proporciones del cuarzo y ópalo, indica la circulación efectiva de fluidos calientes. El origen de estos fluidos estaría en zonas profundas por debajo de la isla, donde se produciría la disolución de la sílice a partir de areniscas y radiolaritas, movilizándose de esta manera este componente hacia la superficie en forma de coloides de Si(OH) 4 . El estudio en profundidad del ópalo indica la presencia de fases tipo A-inicio de CT y C. Si se tiene en cuenta el tiempo en el que se producen estas transformaciones en la evolución diagenética de esta fase amorfa (10.000-50.000 años), indicaría la presencia de un proceso acelerador que podría estar relacionado con una importante circulación de fluidos o con procesos de alteración meteórica capaces, de producir estas transformaciones en unas lavas de menos de 300 años.Palabras clave: alteración hidrotermal, ópalo-A, ópalo-C, sistema hidrológico, erupción Timanfaya, Lanzarote. ABSTRACTThe presence of hydrothermal alterations within the lavas of Timanfaya eruption (1730-1736), with high proportions of quartz and opal, suggests the effective circulation of hot fluids. The source of these fluids would be located under the island, where silica would be dissolved from sandstones and radiolarites, moving this way towards the surface as Si(OH) 4 colloids. Study of opal indicates the presence of Ainitial CT and C phases in the collected samples which, considering the time needed for producing this phase transformations in the diagenetic evolution of opal (10,000-50,000 years), suggests an accelerating process, probably related with either the presence of fluid circulation or weathering processes. Such circumstances are necessary for explaining the presence of such components affecting 300 years old lavas.

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Silica phases in sinters and residues from geothermal fields of New Zealand

Cited by 157 publications

References 43 publications

Geochemical Enhancement Of Enhanced Geothermal System Reservoirs: An Integrated Field And Geochemical Approach

Geochemical Enhancement Of Enhanced Geothermal System Reservoirs: An Integrated Field And Geochemical Approach

Opal-A in Glassy Pumice, Acid Alteration, and the 1817 Phreatomagmatic Eruption at Kawah Ijen (Java), Indonesia

Las alteraciones silíceas de las lavas de Montaña Señalo, erupción de Timanfaya (1730-1736) (Lanzarote, Islas Canarias)

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