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Ankerite
About: Ankerite is a research topic. Over the lifetime, 859 publications have been published within this topic receiving 23960 citations.
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TL;DR: In this paper, the mineralogical and chemical compositions of carbonate phases occurring in strongly altered Triassic volcanic rocks, hosting a CO2 reservoir (namely the Caprese Reservoir), located in eastern Tuscany (central Italy).
3 citations
3 citations
Dissertation•
01 Jan 2016
TL;DR: In this article, the authors present a Table of Table of contents for the paper "Acknowledgements and acknowledgements of the authors of this paper: https://www.goprocessor.org/
Abstract: ................................................................................................................. iii Acknowledgements ................................................................................................ iii Table of
3 citations
01 Jan 1999
TL;DR: The antimony deposits of the Hyundong mine, located in the northeastern part of the Sobaegsan massif, occur as hydrothermal quartz+carbonate veins and stockworks which fill the fault fractures developed in granitic gneiss.
Abstract: The antimony deposits of the Hyundong mine, located in the northeastern part of the Sobaegsan massif, occur as hydrothermal quartz+carbonate veins and stockworks which fill the fault fractures developed in Precambrian metamOlphic rocks (mainly, granitic gneiss). Hydrothermal alteration occurs commonly in the vicinity of mineralized veins and is characterized by sericitization and silicification. A K-Ar age of alteration sericite is 139.2 4.4 Ma, implying the early Cretaceous age of mineralization, possibly in association with intrusion of nearby acidic dikes (mainly, quartz porphyry). The hydrothermal mineralization occurred in five mineralization stages. These are: (I) stage I, characterized by deposition of chalcedonic quartz; (2) stage II, deposition of quartz with base-metal sulfides and stibnite; (3) stage III, deposition of quartz and carbonates (calcite, dolomite, ankerite, rhodochrosite) with various antimony-bearing minerals such as stibnite, polybasite, berthierite, native antimony, gudmundite and ullmannite; (4) stage IV, deposition of calcite with stibnite; and (5) stage V, deposition of barren calcite. Antimony occurs mostly as stibnite within stages II to IV veins, which has various habits including disseminated, veinlets and euhedral coarse crystals. Fluid inclusion studies indicate that hydrothermal mineralization at Hyundong occurred from the fluids with temperature and salinity of C to 120 and 5.3 wI. % equiv. NaCI. The temperature and salinity of ore fluids systematically decreased with elapsed time in the course of mineralization, possibly due to the influx of larger amounts of meteoric groundwater. The deposition of antimony-bearing minerals occurred at low temperatures «C), mainly due to the cooling and dilution of fluids. Based on the evidence of fluid boiling during the early stage II mineralization, the mineralization occurred under low pressure conditions (about 80 bars, corresponding to depths of about 350 m under hydrostatic pressure regime). Thermodynamic considerations of ore . mineral assemblages indicate that antimony deposition also occurred as the results of decreases in temperature and sulfur fugacity of hydrothermal fluids. Calculated sulfur isotope composition of ore fluids (=5.4 to 7.8) indicates an igneous source of sulfur.
3 citations
11 May 2011
TL;DR: In this paper, compositional data related to atomic % content of Ca, Fe, and Mg in carbonates minerals were transformed by using Isometric Log-Ratio balances, whilst the variability affecting the data pattern was investigated in simple binary diagrams.
Abstract: Understanding the physical-chemical features of liquid, gas and solid phases in natural analogue
reservoirs of Carbon Capture and Sequestration (CCS) site is fundamental as they can provide key
data for building up both conceptual and numerical modeling of reaction path for gas-water-rock
interaction in high pCO2 systems. The aim of this work is improve the knowledge about these
processes, by employing appropriate methods for compositional data on a case study, focusing on
the solid (minerals) phases.
In the early eighties, the PSS1 well (Eastern Tuscany, Central Italy), drilled down to almost
5,000 m for oil exploration by ENI (Italian National Agency of Hydrocarbons), intercepted a high
pressure (≈700 bar) CO2 reservoir at the temperature of 120 °C. The reservoir rocks in the fertile
horizon, located at about 3,800 m, consist of altered volcanic deposits interbedded with gypsumdolomite-bearing
evaporites (“Burano Formation”). Surveys for determining the actual paragenesis
of volcanic rocks, carried out on the drill core samples, corresponded to the top of CO2 reservoir
(3,864-3,871 m depths from surface on the PSS1 bore-well log). Quartz, Ca-Fe-Mg carbonates, clay
minerals (illite and chlorite series) and Fe-Ti oxides were found as principal mineralogical phases.
Electron Microprobe Analysis on the carbonates has allowed to recognize the presence of ankerite
and calcites.
Compositional data, related to atomic % content of Ca, Fe, and Mg in carbonates minerals, were
transformed by using Isometric Log-Ratio balances, whilst the variability affecting the data pattern
was investigated in simple binary diagrams. The stoichiometric substitution processes governing the
presence of Ca, Fe and Mg in carbonates were modeled by using regression techniques in the new
space defined by ilrs coordinates. Results have evidenced the different role of Fe and Mg in
substituting or not Ca in both carbonate minerals of these CO2-bearing reservoir rocks
3 citations