Chemical composition of natural deep and shallow hydrothermal fluids in the larderello geothermal field

1992 ◽  
Vol 49 (3-4) ◽  
pp. 313-328 ◽  
Author(s):  
Vittorio Duchi ◽  
Angelo Minissale ◽  
Mirco Manganelli
Keyword(s):  
Chemical Composition ◽  
Geothermal Field ◽  
Hydrothermal Fluids

scholarly journals Orange opals from Buriti dos Montes, Piauí: solid inclusions as genetic guides

2015 ◽  
Vol 68 (1) ◽  
pp. 53-59 ◽  
Author(s):  
Gisele Tavares Marques ◽  
Marcondes Lima da Costa ◽  
Érico Rodrigues Gomes
Keyword(s):  
Chemical Composition ◽  
Aqueous Solutions ◽  
High Stability ◽  
Hydrothermal Fluids ◽  
Northeastern Brazil ◽  
Quartz Crystals ◽  
Hydrothermal Processes ◽  
Hydrothermal Environment

Orange opals from Buriti dos Montes (Piauí, northeastern Brazil) have gemological properties that favor their use as jewelry; these characteristics include their colors, transparency, relatively high stability and hardness. The exotic content of solid inclusions provides greater beauty to the opals of this region. These opals originated from hydrothermal processes and are found mainly as veinlets and veins in the sandstones of the Serra Grande Group, sectioned by diabase dikes and sills of the Sardinha Formation. Solid inclusions, such as bubbles, botryoidal aggregates, dendrites, and nodules, among others, consist mainly of kaolinite, hematite/goethite and quartz and influence the chemical composition of opals. Intense zoning of quartz crystals and high values of Ba and Fe suggest that opal deposits were formed in a hydrothermal environment. Diabase dykes could have been responsible for heating the hydrothermal fluids. Sandstones, rich in aqueous solutions, also contributed to the available silica for the saturation of these solutions, and fractures enabled the migration and entrapment of hydrothermal fluids, resulting in the mineralized veins.

Application of chlorite thermometry to estimation of formation temperature and redox conditions

Clay Minerals ◽  
2018 ◽  
Vol 53 (2) ◽  
pp. 143-158 ◽  
Author(s):  
Atsuyuki Inoue ◽  
Sayako Inoué ◽  
Minoru Utada
Keyword(s):  
Chemical Composition ◽  
Formation Process ◽  
Mineral Assemblage ◽  
Geothermal Field ◽  
Present Approach ◽  
Redox Conditions ◽  
Data Sets ◽  
Formation Temperature ◽  
Semi Empirical

ABSTRACTDiverse applications of chlorite thermometry have been considered for better understanding the formation process in nature. Here, an approach which combined a semi-empirical thermometer (Inoueet al.,2009) with the method of Walshe (1986) was tested to estimate the redox conditions (logfO2) and the formation temperature, using the literature data from Niger, Rouez and St Martin and new data for chlorite which coexists with pink-coloured epidote in the Noboribetsu geothermal field. The logfO2predicted for the former data sets were compatible with those estimated by Vidalet al.(2016), suggesting that the present approach is valid for quantifying the variations in logfO2. The Noboribetsu chlorites have lower Fe/(Fe + Mn + Mg) and greater Fe3+/ΣFe ratios than those observed in adjacent propylite rocks. The peculiar mineral assemblage and chemical composition are attributed to the formation under higherfO2conditions and possibly low Fe concentration in the alteration fluids.

scholarly journals A study on Chinese ancient jades with mercury alteration unearthed from Lizhou’ao Tomb

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yi Bao ◽  
Changqing Xu ◽  
Qinwen Zhu ◽  
Yuesheng Li
Keyword(s):  
Chemical Composition ◽  
Surface Water ◽  
Human Activity ◽  
Environmental Conditions ◽  
Structural Changes ◽  
Hydrothermal Fluids ◽  
Jiangxi Province ◽  
High Grade ◽  
Structural Hierarchy ◽  
Spring And Autumn Period

Abstract“Alteration” geologically refers to chemical composition and/or structural changes of minerals under the influences of hydrothermal fluids, surface water, seawater, or other environmental conditions. In this paper, we use the word “alteration” to refer to chemical component and structural changes in jade artifacts caused by human activity and natural weathering, which is different from the term in geology. “Mercury alteration”, a kind of black alteration related to Hg, is unique among the several types of alteration that occur in Chinese ancient jades. Mercury alteration often appears on ancient jade artifacts unearthed from high-grade tombs of the pre-Qin period (before 221 B.C.). Therefore, ancient jades with mercury alteration have attracted substantial attention from Chinese archaeologists. This paper reports the use of materials analytic techniques to study such ancient jade fragments. The studied jade samples date to the middle and late periods of the Spring and Autumn Period (~500 B.C.) and were unearthed from Lizhou’ao Tomb in Jiangxi Province, China. Structural analyses revealed the internal microstructure of the ancient jade fragments and the microdistribution of the mercury alteration. The jade fragments exhibit typical characteristics of round holes and structural hierarchy, which imply that the jades were heated before burial. The black alteration on these jade samples was found to be rich in Hg. The results of this study will be widely useful in the study of ancient jade artifacts and jade culture in Chinese archeology.

Source controls on sulfur abundance and isotope fractionation in hydrothermal fluids in the Olkaria geothermal field, Kenya

2021 ◽  
pp. 120446
Author(s):  
Barbara I. Kleine ◽  
Jóhann Gunnarsson-Robin ◽  
Kennedy M. Kamunya ◽  
Shuhei Ono ◽  
Andri Stefánsson
Keyword(s):  
Isotope Fractionation ◽  
Geothermal Field ◽  
Hydrothermal Fluids

Variations in the chemical composition of illite from five geothermal fields: a possible geothermometer

Clay Minerals ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 501-510 ◽  
Author(s):  
S. Battaglia
Keyword(s):  
Chemical Composition ◽  
Correlation Coefficient ◽  
General Relation ◽  
Geothermal Field ◽  
Single Line ◽  
Chemical Compositions ◽  
Geothermal Systems ◽  
Correction Algorithm ◽  
Geothermal Fields

AbstractPrevious attempts to use illite as a geothermometer have failed: no general relation between the mineral's chemical composition and temperature of crystallization has been found. Here, chemical compositions of 27 illite samples from five different geothermal fields (the data on four of which were drawn from the literature) were compared with their crystallization temperatures. As previously reported by Cathelineau (1988), the K content was found to be the only variable yielding a suitable correlation, but only when applied to one geothermal field; when various geothermal systems were considered, the correlation weakened considerably. Introduction of a correction algorithm to the K content of the illite has made it possible to draw a single line to fit the data from all the studied samples, yielding a good correlation coefficient (r = 0.84).

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