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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 article, a 3D reactive transport simulation model for sandstone and carbonate reservoirs was established to simulate the geochemical reactions and their effects on heat mining rate during geothermal exploitation using CO2.
Abstract: CO2 can be injected into geothermal reservoirs to exploit geothermal energy. It is of concern that complex geochemical reactions induced by CO2 can result in change of the reservoir porosity and affect the fluid flow and heat mining rate. In this study, laboratory experiments on CO2–water–rock interactions were conducted to investigate the geochemical reactions using rock samples from typical sandstone and carbonate reservoirs. Based on the experimental results, 3D reactive transport simulation models for sandstone and carbonate reservoirs were established to simulate the geochemical reactions and their effects on heat mining rate during geothermal exploitation using CO2. The potential of CO2 storage in the heat mining process in different geothermal reservoirs was also assessed. The experimental results show that, for the sandstone tested, the presence of CO2 can lead to the dissolution of ankerite and clay minerals and the precipitation of plagioclase, which can result in the increase of Ca2+ and Mg2+ in formation water. For the carbonate tested, CO2 can induce the dissolution of dolomite and the precipitation of ankerite and calcite. The numerical simulation results indicate that the influence of the geochemical reactions on flow behavior and heat mining rate is dependent on the reservoir type and mineral compositions. For the sandstone reservoir, the reduction of the porosity caused by minerals precipitation has a negative effect on heat mining rate, while for the carbonate reservoir, the dissolution of dolomite and clay minerals can overshadow the precipitation effect of calcite and silicate minerals and increase the heat mining rate.
68 citations
TL;DR: In this paper, the petrography and geochemistry of the Hotazel iron-formation of the Kalahari manganese field, South Africa, were presented, which is very similar to Paleoproterozoic banded iron-formations of the Superior type, comprising laminae of chert, iron oxides (magnetite, hematite), iron silicates (greenalite, minnesotaitc, stilpnomelane, riebeckite, Fe mica), carbonates (calcite, anker
Abstract: New data are presented concerning the petrography and geochemistry of the Paleoproterozoic Hotazel iron-formation of the Kalahari manganese field, South Africa. Mineralogically and texturally, the Hotazel iron-formation is very similar to Paleoproterozoic banded iron-formations of the Superior type, comprising laminae of chert, iron oxides (magnetite, hematite), iron silicates (greenalite, minnesotaitc, stilpnomelane, riebeckite, Fe mica), carbonates (calcite, ankerite, minor siderite), and pyrite. The major chemical constituents of the Hotazel rocks are SiO 2 , Fe oxides, CaO, and MgO, whereas MnO, Al 2 O 3 , Na 2 O, and K 2 O contents are negligible (below 1 wt %). Elements of detrital derivation (Ti, Zr, Rb) and transition metals such as Zn, Cu, Ni, Co, and V are present in low concentrations, on the order of a few tens of parts per million.Stratigraphically higher, the Hotazel banded iron-formation shows a conspicuous increase in CaO contents that is coupled with a subtle decrease in bulk-rock Fe number ratios (Fe (super 2+) /(Fe (super 2+) + Fe (super 3+) )), implying a gradual transition to a more oxidizing environment. Shale-normalized rare earth element (REE) patterns are similar to those of older banded iron-formations of the Transvaal Supergroup, exhibiting light REE depletion and negative Ce anomalies comparable to modern shallow-level seawater. Occasional weak positive Eu anomalies in iron silicate-rich rocks indicate minor admixtures of a hydrothermal component below the chemocline. The similarities between the Hotazel iron-formation and most Superior-type banded iron-formations, the lack of transition metal enrichments, and the absence of strongly positive Eu anomalies in the Hotazel rocks challenge volcanogenic exhalative models proposed previously for the genesis of the interbedded Kalahari Mn deposits.
68 citations
TL;DR: Authigenic carbonate minerals are ubiquitous throughout the Late Permian coal measures of the Bowen Basin, Queensland, Australia as discussed by the authors, where they formed as an early diagenetic mineral from meteoric waters under cold climate and reducing conditions.
68 citations
TL;DR: McGoldrick et al. as mentioned in this paper examined the major and trace element chemistry of carbonate-bearing sediments surrounding the Lady Loretta Zn-Pb-Ag deposit and defined a series of halos which extend for several hundred metres across strike and up to 1.5 km along strike.
68 citations
TL;DR: In this paper, the high pressure response of the cell parameters of calcite, CaCO3, has been investigated by single crystal X-ray diffraction, and the unit cell parameters have been refined from 0 to 1.
Abstract: The high-pressure response of the cell parameters of calcite, CaCO3, has been investigated by single crystal X-ray diffraction. The unit cell parameters have been refined from 0 to 1.435 GPa, and the linear and volume compressibilities have been measured as β
a
=2.62(2) × 10−3 GPa−1,β
c
=7.94(7) × 10−3 GPa−1, β
v
=13.12 × 10−3 GPa−1. The bulk modulus has been obtained from a fit to the Birch-Murnaghan equation of state, giving K
0=73.46 ± 0.27 GPa and V
0=367.789 ± 0.004 A3 with K′=4. Combined with earlier data for magnesite, ankerite and dolomite, these data suggest that K
0
V
0 is a constant for the Ca-Mg rhombohedral carbonates.
67 citations