A rock magnetic fingerprint of hydrothermal alteration in volcanic rocks - An example from the Los Azufres Geothermal Field, Mexico

2019 ◽  
Vol 91 ◽  
pp. 260-271
Author(s):  
Kailasa Pandarinath ◽  
Rajasekhariah Shankar ◽  
E. Santoyo ◽  
Shwetha B. Shetty ◽  
America Yosiris García-Soto ◽  
...  
Keyword(s):  
Hydrothermal Alteration ◽  
Volcanic Rocks ◽  
Geothermal Field

Acid-sulphate hydrothermal alteration of andesitic tuffs and genesis of halloysite and alunite deposits in the Biga Peninsula, Turkey

Clay Minerals ◽  
2008 ◽  
Vol 43 (2) ◽  
pp. 281-315 ◽  
Author(s):  
Ö. I. Ece ◽  
P. A. Schroeder ◽  
M. J. Smilley ◽  
J. M. Wampler
Keyword(s):  
Hydrothermal Alteration ◽  
Volcanic Rocks ◽  
Geothermal Field ◽  
Parent Material ◽  
Thermal Waters ◽  
Geothermal Waters ◽  
Biga Peninsula ◽  
The North ◽  
Clay Deposits ◽  
Nw Turkey

AbstractThe Biga Peninsula of NW Turkey is host to six major halloysite deposits in the Go¨nen, Yenice and Balya districts. Mineralization took place in areas of Permian limestone blocks where the Triassic Karakaya Complex is in contact with early Miocene calc-alkaline volcanic rocks. Hypogene halloysite mineralization was controlled by the intersection of minor faults in the vicinity of clay deposits. During the Pleistocene, activity of the North Anatolian Fault (NAF) brought ascending geothermal solutions through the fault zones to the surface, which led to hydrothermal alteration and halloysite formation. N-MORB normalized element values for each halloysite deposit and the volcanic rocks suggest genetic links. Alunite and halloysite were formed in the Turplu area where upwelling hydrothermal waters contained major H2S and SO2acids. Only halloysite mineralization occurred in outflow areas of the same fossil geothermal field.Pyrite and alunite samples from the Turplu deposits have δ34S values of 0.6–1.8% and 4.8–7.9%, respectively, with values for gypsum of 3.1–3.5%. The δ34S values of pyrite suggest that local meteoric waters had partially mixed with the dominant fluid during the closure stage of fossil hydrothermal activities. The range of δD values of halloysite samples from Turplu is –58.4 to –68.6%. The δ18O values for halloysite are in the range 16.7–18.1%. All halloysite deposits in the study areas are either overlying or adjacent to limestone blocks, and these provide excellent drainage for the discharging geothermal waters. Subsurface drainage systems in the karstic environment and the SO2-bearing thermal waters indicate the importance of acidic waters and the continuous leaching of elements in forming relatively pure hydrated halloysite. A steam-heated dissolution-precipitation model is proposed for the occurrence of all halloysite and alunite deposits. Sulphur gases (H2S-SO2) of hypogene origin rose from deep in the fault zone to the surface where they encountered oxygenated groundwater at the water table. The occurrence of H2SO4in this hydrothermal system enhanced the acidity of geothermal waters provoking advanced argillic alteration. Hypogene alunite deposits also have large P2O5contents, suggesting a parent material with a magmatic origin deeper than the alkaline tuffs. Halloysite is a fast-forming metastable precursor to kaolinite.

Hydrothermal alteration effects in geochemistry and Sr, Nd, Pb, and O isotopes of magmas from the Los Azufres geothermal field (Mexico): A statistical approach

2005 ◽  
Vol 39 (2) ◽  
pp. 141-163 ◽  
Author(s):  
Surendra P. Verma ◽  
Ignacio S. Torres-Alvarado ◽  
Muharrem Satir ◽  
Patrick F. Dobson
Keyword(s):  
Hydrothermal Alteration ◽  
Statistical Approach ◽  
Geothermal Field ◽  
O Isotopes

Hydrothermal alteration of volcanic rocks in Seival Mine Cu–mineralization – Camaquã Basin – Brazil (part I): Chloritization process and geochemical dispersion in alteration halos

2017 ◽  
Vol 177 ◽  
pp. 45-60 ◽  
Author(s):  
Eduardo Fontana ◽  
André S. Mexias ◽  
Christophe Renac ◽  
Lauro V.S. Nardi ◽  
Rodrigo W. Lopes ◽  
...  
Keyword(s):  
Hydrothermal Alteration ◽  
Volcanic Rocks ◽  
Geochemical Dispersion

Mineralogical, chemical, and Sr-Nd isotopic effects of hydrothermal alteration of near-surface rhyolite in the Los Azufres geothermal field, Mexico

Lithos ◽  
2018 ◽  
Vol 322 ◽  
pp. 347-361
Author(s):  
Surendra P. Verma ◽  
Kailasa Pandarinath ◽  
Rajneesh Bhutani ◽  
Jitendra K. Dash
Keyword(s):  
Hydrothermal Alteration ◽  
Geothermal Field ◽  
Near Surface ◽  
Isotopic Effects

scholarly journals Mineralogical and Fluid Inclusions Study of Epithermal Type Veins Intruding the Volcanic Rocks of the Kornofolia Area, Evros, NE Greece.

2019 ◽  
Vol 55 (1) ◽  
pp. 202
Author(s):  
Foteini Aravani ◽  
Lambrini Papadopoulou ◽  
Vasileios Melfos ◽  
Triantafillos Soldatos ◽  
Triantafillia Zorba ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Fluid Inclusion ◽  
Hydrothermal Alteration ◽  
Fluid Inclusions ◽  
Volcanic Rocks ◽  
The Other ◽  
Calc Alkaline ◽  
Ft Ir ◽  
Host Rocks

The volcanic rocks of Kornofolia area, Evros, host a number of epithermal-type veins. The host rocks are Oligocene calc-alkaline andesites to rhyo-dacites. The andesites form hydrothermal breccias and show hydrothermal alteration. The veins comprise mainly silica polymorphs such as quartz, chalcedony and three types of opal (milky white, transparent and green). Amethyst also forms in veins at the same area. Apart from the silica polymorphs, the veins are accompanied by calcite and zeolites. The main aim of this study is the characterization of the silica polymorphs. Using FT-IR analyses, variations in the crystal structure of the three opals were recognized. The green opal is found to be more amorphous than the other two types. Fluid-inclusion measurements were performed in calcite and were compared with amethyst from previous studies. The Th is between 121-175 °C and the Te between -22.9 and -22.4 °C. The salinities range from 0.9 to 4.5 wt % NaCl equiv.

Dosage du potassium, de l'uranium, du radium et du thorium, par spectrometrie gamma dans les laves d'Auvergne, du Velay et de la province sicilienne

1963 ◽  
Vol S7-V (2) ◽  
pp. 218-231 ◽  
Author(s):  
Jean Louis Cheminee ◽  
Daniel Nordemann
Keyword(s):  
Hydrothermal Alteration ◽  
Volcanic Rocks ◽  
Statistical Dependence ◽  
Direct Proportion ◽  
Radioactive Elements ◽  
Spectrometry Analysis ◽  
Functional Relations ◽  
South Central ◽  
Intrusive Rocks ◽  
Radioactive Minerals

Abstract Fifty samples of volcanic rocks from south-central France, ranging from basalts to rhyolites, were subjected to gamma spectrometry analysis for the purpose of determining the proportions and relationships of the constituent radioactive elements. Zircon, sphene and apatite generally contained less thorium and uranium than the less abundant accessory minerals such as allanite, monazite and xenotime. Results of the analysis also show that the percentage of radioactive minerals is greater in the acidic lavas than in the intrusive rocks, suggesting that the latter were subjected to hydrothermal alteration. The percentage of potassium varies in direct proportion to the variation in the percentage of silica. The increase in thorium as a function of silica is more rapid than that of uranium. Graphically, no correlation exists between the percentage of radium and silica. The concentrations of uranium and thorium do not vary independently but seem to have a statistical dependence whose functional relations are not yet apparent.

scholarly journals Remote sensing of surface Hydrothermal Alteration, identification of Minerals and Thermal anomalies at Sveifluháls-Krýsuvík high-temperature Geothermal field, SW Iceland

2019 ◽  
Vol 254 ◽  
pp. 012005
Author(s):  
Lucía Magali Ramírez-González ◽  
Muhammad Aufaristama ◽  
Ingibjörg Jónsdóttir ◽  
Ármann Höskuldsson ◽  
þorvaldur þórðarson ◽  
...  
Keyword(s):  
Remote Sensing ◽  
High Temperature ◽  
Hydrothermal Alteration ◽  
Geothermal Field ◽  
Thermal Anomalies
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