Journal of GEOsciences Table of Contents for the Journal of GEOsciences. List of articles from the latest print issue.http://www.jgeosci.orgen-US Journal of GEOscienceshttp://www.jgeosci.org/img-system/jgeosci_cover.jpghttp://www.jgeosci.org <![CDATA[ WinGrt, a Windows program for garnet supergroup minerals ]]> Yavuz F, Yildirim DK; Vol. 65, issue 2, pages 71 - 95
A Microsoft® Visual Basic software, called WinGrt, has been developed to calculate and classify wet-chemical and electron-microprobe garnet supergroup mineral analyses. The program evaluates 33 approved species that belong to the tetragonal henritermierite and isometric bitikleite, schorlomite, garnet and berzeliite groups based on the Commission on New Minerals and Mineral Names (CNMMN) of the International Mineralogical Association (IMA-13) nomenclature scheme. WinGrt also evaluates thirty geothermometers using the Fe2+-Mg exchange reactions for garnet-biotite, garnet-clinopyroxene and garnet-orthopyroxene pairs within the application range of greenschist-, amphibolite-, granulite- and eclogite-facies metamorphic rocks. As naturally occurring garnet is potentially a useful provenance indicator, the program calculates end-member molecules from chemical compositions on the basis of different approaches and yields pyrope, almandine, spessartine, grossular, andradite and schorlomite phase on various ternary discrimination diagrams used in provenance studies. The ferric and ferrous iron contents from total FeO (wt. %) amount are estimated by stoichiometric constraints. The program allows the users to enter 30 input variables including Sample No, SiO2, TiO2, ZrO2, HfO2, Th2O, SnO2, Al2O3, Cr2O3, V2O3, Fe2O3, Mn2O3, Sc2O3, Y2O3 + REE2O3, FeO, MgO, MnO, ZnO, CaO, Na2O, Li2O, P2O5, V2O5, Sb2O5, As2O5, Nb2O5, UO3, Te2O3, F and H2O (wt. %). WinGrt also enables the user to enter the total REE2O3 (wt. %) as input values from La2O3 to Lu2O3 (wt. %) of garnet supergroup mineral analyses in program’s data edit section. WinGrt enables the user to type or load multiple garnet compositions in the data entry section, to edit and load Microsoft® Excel files in calculating, classifying and naming the garnet species, and to store all the calculated parameters in the Microsoft® Excel file for further evaluations by the users. ]]>
http://www.jgeosci.org/rss.php?ID=jgeosci.303 Original paper http://www.jgeosci.org/rss.php?ID=jgeosci.303
<![CDATA[ Indium-bearing paragenesis from the Nueva Esperanza and Restauradora veins, Capillitas mine, Argentina ]]> Márquez-Zavalía MF, Vymazalová A, Galliski MÁ, Watanabe Y, Murakami H; Vol. 65, issue 2, pages 97 - 109
The Nueva Esperanza and Restauradora are two of the twenty-three veins described at Capillitas mine, an epithermal precious- and base-metal vein deposit located in northern Argentina. Capillitas is genetically linked to other mineralizations of the Farallón Negro Volcanic Complex, which hosts several deposits. These include two world-class (La Alumbrera and Agua Rica) and some smaller (e.g., Bajo El Durazno) porphyry deposits, and a few epithermal deposits (Farallón Negro, Alto de la Blenda, Cerro Atajo and Capillitas). The main hypogene minerals found at these two veins include pyrite, sphalerite, galena, chalcopyrite, tennantite-(Zn) and tennantite-(Fe). Accessory minerals comprise hübnerite, gold, silver, stannite, stannoidite and mawsonite, and also diverse indium- and tellurium-bearing minerals. Quartz is the main gangue mineral.
Indium participates in the structure of sphalerite, tennantite-(Zn), ishiharaite and an indium-bearing mineral, still under study, the former being the most abundant of these phases. The chemical composition of sphalerite shows very low concentrations of Fe and a wide range in indium contents from below the detection limit (0.03 wt. %) to values close to 22 wt. %. Atomic proportions of In and Cu correlate positively at a ratio In : Cu = 1 : 1 atoms per formula unit. Cadmium reaches up to 0.68 wt. %. Other analyzed elements (Ga, Ge, As, Se, Ag, Sn, Sb, Te, Au, Pb and Bi) are systematically below their respective detection limits. Indium-bearing tennantite-(Zn) (up to 0.24 wt. % In) is rare and restricted to the area where ishiharaite appears. Ishiharaite and the unclassified indium-bearing mineral are extremely scarce and host up to 10 and 30 wt. % In, respectively.
The zoning in sphalerite and the variable indium content of the different bands could be ascribed to significant fluctuation in the composition of the fluids (possibly pulses). They are evidenced by the presence of a high f Te2 mineral, like calaverite, and a low f Te2 phase, such as silver, within the same stage, with local periodic increments on In and Cu that could also be associated with recurring reactivation of fractures. ]]>
http://www.jgeosci.org/rss.php?ID=jgeosci.304 Original paper http://www.jgeosci.org/rss.php?ID=jgeosci.304
<![CDATA[ Molecular structure of the arsenate mineral chongite from Jáchymov – a vibrational spectroscopy study ]]> Sejkora J, Plášil J, Čejka J, Dolníček Z, Pavlíček R; Vol. 65, issue 2, pages 111 - 120
We have undertaken a study of the arsenate mineral chongite from the second world occurrence, which is Jáchymov (Czech Republic). Chongite occurs as colourless to white crystalline spherical and hemispherical aggregates up to 0.3 mm across composed of rich crusts on strongly weathered fragments of rocks and gangue. The chemical composition of chongite agrees well with the general stoichiometry of the hureaulite group of minerals and corresponds to the following empirical formula: Ca1.00(Mg1.24Ca0.69 0.06Mn0.01)Σ2.00Ca2.00[(AsO3OH)2.13(AsO4)1.84(PO4)0.03]Σ4.00·4H2O. Chongite is monoclinic, space group C2/c, with the unit-cell parameters refined from X-ray powder diffraction data: a 18.618(5), b 9.421(2), c 9.988(2) Å, β 96.86(2)o and V 1739.4(7) Å3. Raman bands at 3456, 3400, 3194 cm-1 and infrared bands at 3450, 3348, 3201 and 3071 cm-1 are assigned to the ν OH stretching structurally distinct differently hydrogen bonded water molecules. Raman bands at 2887, 2416 cm-1 and infrared bands at 2904, 2783 cm-1 are connected to ν OH stretching in hydrogen bonded (AsO3OH)2- units. Raman bands at 1656, 1578 cm-1 and infrared bands at 1652, 1601 cm-1 are assigned to the ν2 (δ) H2O bending vibrations of structurally distinct hydrogen bonded water molecules bonded in the structure by H-bonds of various strength. A Raman band at 1284 cm-1 and infrared bands at 1091 and 1061 cm-1 may be connected to the δ As-OH bending vibrations. The most prominent Raman bands at 902, 861, 828, 807, 758 cm-1 and infrared bands at 932, 899, 863, 815, 746 cm-1 are attributed to overlapping ν1 (AsO4)3- symmetric stretching, ν3 (AsO4)3- antisymmetric stretching, ν1 (AsO3OH)2- symmetric stretching, and ν3 (AsO3OH)2- antisymmetric stretching vibrations. Raman band at 693 cm-1 and infrared bands at 721, 634 cm-1 are assigned to δ AsOH bend and molecular water libration modes. Raman bands 506, 469, 451, 436 cm-1 and infrared bands at 503, 466 and 417 cm-1 are connected with the ν4 (δ) (AsO4)3- and (HOAsO3)2- bending vibrations. Raman bands at 389, 360, 346 and 302 cm-1 are related to the ν2 (δ) (AsO4)3- and (HOAsO3)2- bending vibrations. Raman bands at 275 and 238 cm-1 are assigned to the ν (OH•••O) stretching vibrations and those at 190, 162, 110, 100 and 75 cm-1 to lattice modes. ]]>
http://www.jgeosci.org/rss.php?ID=jgeosci.292 Original Paper http://www.jgeosci.org/rss.php?ID=jgeosci.292
<![CDATA[ Was the Tynong Batholith, Lachlan Orogen, Australia, extremely hot? Application of pseudosection modelling and TitaniQ geothermometry ]]> Regmi KR, Hasalová P, Nicholls IA; Vol. 65, issue 2, pages 121 - 138
Tonalites to granites of the Tynong Batholith, Lachlan Orogen, southeastern Australia as well as enclaves within them contain primary clino- and orthopyroxenes. These plutons produced very broad (2-10 km) contact aureoles that contain an anatectic zone within metagreywackes. The very broad contact aureoles can be related to the 3-D shapes of the plutons and we assume that the Cpx and Opx are remnants of higher temperature crystallization that were preserved due to water loss or low water content in the magma. Estimates of P and T based on x(Fe) values for coexisting cordierite and biotite in P-T pseudosections for a typical migmatitic hornfels, providing minimum temperature of pluton emplacement, indicate emplacement of the Toorongo tonalite at 4-10 km (1-3 kbar) and 680-750 °C. However, the isopleths of An content of plagioclase indicate depths of up to 14 km at 660-740 °C. We suggest that plagioclase was partially re-equilibrated during melt loss and post-emplacement decompression.
Cathodoluminescence (CL) imaging shows that quartz both in the tonalities and hornfels is typically zoned from higher Ti contents in cores to lower in the margins, suggesting a response to falling temperature. Calculated temperatures for quartz crystallization using a Ti-in-quartz calibrated for 2.5 kbar gave a wide range of values between 900 and 500 °C. This suggests that although the granitoids contain two pyroxenes and have produced a broad contact aureole, they were not emplaced at temperatures as high as previously inferred. ]]>
http://www.jgeosci.org/rss.php?ID=jgeosci.305 Original paper http://www.jgeosci.org/rss.php?ID=jgeosci.305