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  • 1
    Electronic Resource
    Electronic Resource
    Classification and mineralization potential of the pegmatites of the Eastern Brazilian Pegmatite Province (2000)
    Springer
    Mineralium deposita 35 (2000), S. 638-655 
    Details
    ISSN: 1432-1866
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The potential for Nb, Ta, Li, Sn-mineralization as well as for precious stones for the Eastern Brazilian Pegmatite Province (EBPP) has been evaluated on the basis of 530 K-feldspar and 550 muscovite major and trace element analyses. The EBPP is situated mainly in the State of Minas Gerais, but encompasses also parts of the States of Bahia, Espírito Santo and Rio de Janeiro. The EBPP is the largest pegmatite province of South America. It was divided into the pegmatite districts of Itambé, Araçuaí, Safira, Nova Era, Aimorés and Espera Feliz. This was done to test whether the pegmatites of these districts differ in their mineralization potential and how geotectonic setting influences mineralization potential. The fractionation diagrams such as Cs, Zn, Li, Be, Ba versus K/Rb, Cs versus Ta/(Ta + Nb), and U, Na2O versus K/Cs for the pegmatite districts of Araçuaí and Safira show the widest range in fractionation. These pegmatite districts are leaders in the production of gem-quality tourmaline, aquamarine, morganite, and contain abundant spodumene, tantalite and columbite. In contrast, the Espera Feliz and Aimorés pegmatite districts are the most primitive districts examined and have a corresponding lack of rare-element mineralization. Literature data indicate that all studied pegmatites are of Brasiliano age, i.e., formed between 600 and 480 Ma. The pegmatites of Transamazonic age (1.9 Ga), found rarely in the study area, are of economic importance in the context of emerald mineralization, but seem to be of less importance for rare metal and other gemstone mineralization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001260050268
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  • 2
    Electronic Resource
    Electronic Resource
    Fluid inclusion microthermometry and the P-T evolution of gold-bearing hydrothermal fluids in the Niuxinshan gold deposit, eastern Hebei province, NE China (1999)
    Springer
    Mineralium deposita 34 (1999), S. 348-365 
    Details
    ISSN: 1432-1866
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Niuxinshan is a typical example of the numerous mesothermal gold deposits formed during Mesozoic tectono-magmatic reactivation of the Archean North China Craton in eastern Hebei province. Gold occurs in quartz-sulfide lodes in Archean amphibolites and also in greisen zones in the Mesozoic Niuxinshan granite stock. Four mineralization stages can be recognized from early to late: (1) quartz-K-feldspar, (2) quartz-pyrite, (3) quartz-polysulfide, and (4) quartz-carbonate. Gold mineralization mainly occurs in stages 2 and 3. Fluid inclusions in quartz and fluorite from greisen zones in the Niuxinshan granite, and inclusions in vein quartz and sphalerite from stages 1 to 3 in the amphibolites, have been studied by microthermometry. Three compositional types of inclusions are recognized: type 1 (Tp1) are H2O-CO2-bearing inclusions and include primary (Tp1-P) and secondary (Tp1-S) inclusions. These are found in quartz and fluorite from the greisen zones as well as in vein quartz and sphalerite from stages 1 to 3. The Tp1-P inclusions are considered to represent the gold-bearing hydrothermal fluids. Type 2 (Tp2-S) are secondary H2O-CO2 + solid phase inclusions in fluorite from the greisen zones. Type 3 (Tp3-S) are secondary aqueous inclusions with a solid phase which coexist with the Tp2-S in fluorite from the greisen zones. The Tp1-P inclusions show variable VCO2 (commonly 0.3 to 0.6) and XCO2 values (mainly 0.1 to 0.4). The salinities of inclusions cluster around 3 to 11 wt.% NaCl equivalent and their homogenization temperatures to the liquid phase (Th(L)) fall dominantly in the range of 260 to 360 °C. The compositional variations of inclusions in stage 1 probably result from exsolution of magmatic fluids at various stages; immiscibility or boiling of the fluids can be ruled out. The compositional variations of inclusions in the greisen zones and in vein stages 2 and 3 are attributed to cooling, mixing (dilution), and necking-down of the fluids. The Tp1-S and Tp2-S inclusions show salinities of 3 to 6 wt.% NaCl equivalent and XCO2 values of 0.04 to 0.17. Th(L) clusters at 240 to 260 °C. The Tp3-S inclusions have salinities of 3 to 6 wt.% NaCl equivalent and Th(L) of 170 to 240 °C. Isochoric reconstructions, combined with oxygen and sulfur isotope geothermometry of mineral pairs, give trapping P-T conditions for the gold-bearing fluids. The greisen zones formed at 310 to 460 °C and 1.3 to 3.7 kbar; stage 1 veins at 300 to 430 °C and 1.2 to 3.7 kbar; stage 2 veins at 290 to 380 °C and 1 to 3 kbar; stage 3 veins at 250 to 350 °C and 1 to 3 kbar. H2O-CO2 fluids with low to moderate salinities and moderate to high densities (0.66 to 1.01 g/cm3) dominated at early mineralization stages, and evolved towards H2O-richer and CO2- and less saline fluids through time. The retrograde P-T evolution probably resulted from regional uplift and cooling of gold-bearing hydrothermal fluids. The gold bisulfide complex was dominant in the fluids during mineralization and gold deposition was mainly induced by decreases of temperature and pressure, as well as destabilization of the bisulfide complex during sulfidization of wall rocks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001260050209
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  • 3
    Electronic Resource
    Electronic Resource
    Fluid channelling during ductile shearing: transformation of granodiorite into aluminous schist in the Tauern Window, Eastern Alps (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of metamorphic geology 9 (1991), S. 0 
    Details
    ISSN: 1525-1314
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Abstract Ductile shearing in the core of the Tauern Window, Austria, transformed metagranodiorite into Si-undersaturated garnet-chlorite-staurolite schist at a depth of c. 35–40 km during the Alpine orogeny. Four distinct zones have been recognized extending from the wallrock into the centre of the shear zone: Zone I—unaltered metagranodiorite with subordinate amphibolite; Zone II—biotite-white mica-garnet schist; Zone III—biotite-phengite schist; Zone IV—quartz-absent, garnet-chlorite-staurolite schist with garnets up to 10 cm across. Whole-rock analyses show a dramatic decrease in SiO2 from 〉65 wt% in Zone I to 〈35 wt% in Zone IV; Ca, Na, and Sr also decrease across the shear zone, whereas Al, Ti, Fe, Mg, P, Cr, Ni, Zn, and Rb all increase towards Zone IV. Mass-balance calculations indicate that shearing was accompanied by up to 60% volume loss near the centre of the shear zone. Comparison of the Tauern Window samples with other shear zones in granitic hosts indicates that silica loss accompanied by gains in Mg, Fe, and Ti is typical for volume-loss shear zones, but is distinctly different from the element behaviour exhibited in shear zones that are thought to represent approximately isovolumetric behaviour. In the samples studied here, volume loss appears to have resulted from channellized fluid flow during shearing, producing time-integrated fluid fluxes of ± 108 cm3 cm−2 in Zone IV. This large volume of fluid may have originated, in part, from dehydration of flysch carried beneath the metagranodiorites during Eocene movement on the North Penninic subduction zone. Development of an inverted thermal gradient during subduction would have allowed the fluid to scavenge large amounts of silica from the shear zone during ascent and heating.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1525-1314.1991.tb00536.x
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  • 4
    Electronic Resource
    Electronic Resource
    Determination of erosion rates with cosmogenic ^2^6Al
    Amsterdam : Elsevier
    Nuclear Inst. and Methods in Physics Research, B 92 (1994), S. 317-320 
    Details
    ISSN: 0168-583X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0168-583X(94)96026-7
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  • 5
    Electronic Resource
    Electronic Resource
    Im Gedenken an Bruno Sander (1983)
    Springer
    International journal of earth sciences 72 (1983), S. V 
    Details
    ISSN: 1437-3262
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01822073
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  • 6
    Electronic Resource
    Electronic Resource
    Mineralogical and chemical composition of some carbonate minerals from the Zillerthal Alps, Tyrol (Austria) (1972)
    Springer
    Mineralogy and petrology 17 (1972), S. 46-59 
    Details
    ISSN: 1438-1168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung 32 Karbonatproben aus den Zillertaler Alpen (Tirol, Österreich) wurden mit optischen und röntgendiffraktometrischen Methoden sowie mit dem Elektronenrastermikroskop untersucht. Die Karbonate sind Calcite, die bis zu 11 Mol% (MgCO3+FeCO3) enthalten. Die Calcitkristalle zeichnen sich durch skelettartige Dolomitentmischungen aus, die parallel zu Rhomboederflächen des Calcites orientiert sind. Die Karbonate stammen aus einer Serie metamorpher Gesteine der Grünschiefer- bis Almandin-Amphibolitfazies. Es werden die Beziehungen zwischen der Calcitzusammensetzung und dem Metamorphosegrad diskutiert. Der (FeCO3+MgCO3)-Gehalt der Calcite hängt von der Bildungstemperatur, vom CO2-Druck und vom Fe- und Mg-Gehalt der Lösungen ab, aus denen sich die Karbonate gebildet haben.
    Notes: Summary 32 carbonate samples from a series of metamorphic rocks of greenschist to almandine-amphibolite facies in the Zillerthal Alps were investigated by optical and chemical methods, X-ray diffractometry, and the scanning electron microscope. The carbonates consist mainly of calcite which contains up to 11 mole % (MgCO3+FeCO3). Some of the calcites are characterized by skeleton-like dolomitic exsolutions of rhombohedral shape that are orientated on rhombohedron planes of the calcite matrix. The relations between metamorphic grade and calcite composition will be discussed. The (FeCO3+MgCO3)-content of calcite depends on the temperature of formation, CO2 pressure, and the Fe and Mg concentrations of the carbonate-forming solutions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01082920
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  • 7
    Electronic Resource
    Electronic Resource
    Experimental determination of the upper stability of scorzalite, FeAl2[OH/PO4]2, and the occurrence of minerals with a composition intermediate between scorzalite and lazulite(ss) up to the conditions of the amphibolite facies (1997)
    Springer
    Mineralogy and petrology 61 (1997), S. 211-222 
    Details
    ISSN: 1438-1168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung Das Stabilitätsfeld von Skorzalith (FeAl2[OH/PO4]2) wurde im P-T-Bereich zwischen 487 und 684 °C und zwischen 0.1 und 0.3 GPa in Hydrothermalexperimenten unter der Sauerstoffugazität des Ni/NiO-Puffers untersucht. Skorzalith zerfällt unter diesen Bedingungen gemäß der Reaktion: FeAl2[OH/PO4]2) → FeAlPO5 + AlPO4 (Berlinit) + H2O. Die Reaktionsenthalpie und -entropie für Standardbedingungen wurden zu ΔH R 0 = 94(13) kJ und ASR = 180(16) JK−1 bestimmt.57 Fe-Mößbaueruntersuchungen ergaben, daß ungefähr 4% des Gesamteisens in Skorzalith dreiwertig vorliegen.
    Notes: Summary The stability field of scorzalite (FeAl2[OH/PO4]2) was investigated in the P-T range from 487 to 684 °C and 0.1 to 0.3 GPa. in hydrothermal experiments. The oxygen fugacity was fixed by the Ni/NiO buffer. Scorzalite shows a decomposition according to the reaction: FeAl2[OH/PO4]2) → FeAlPO5 + AlPO4 (berlinite) + H2O. The mean standard enthalpy and standard entropy of reaction were determined as ΔH R 0 = 94(13) kJ, ASR = 180(16) JK−1. A57Fe-Mößbauer spectroscopic examination showed that about 4 atomic % of the total Fe in scorzalite is trivalent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01172485
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  • 8
    Electronic Resource
    Electronic Resource
    Enclaves in the S-type granites of the Kösseine massif (Fichtelgebirge, Germany): implications for the origin of granites (1997)
    Springer
    Geologische Rundschau 86 (1997), S. S125 
    Details
    ISSN: 0016-7835
    Keywords: Key words Enclaves ; S-type granites ; Contact metamorphism ; Nd- and Sr-isotopes ; Fichtelgebirge ; Hercynian granites ; Petrography ; Geochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  The Hercynian peraluminous granites of the Kösseine massif differ in composition and content of enclaves from the other granites of the Fichtelgebirge. They are garnet-, cordierite- and andalusite-bearing S-type granites containing at least five different types of enclaves. Based on petrography and geochemical data, including radiogenic isotopes, the following is concluded: The amphibolite enclave (AE) and most of the aluminium silicate-bearing surmicaceous enclaves (SEA) are country-rock xenoliths picked up by the granite at or close to the emplacement level. The orthopyroxene-bearing surmicaceous enclave (SEO) probably represents a restite from the source level of the granite. The gneiss enclaves (GE) could be fragments of Saxothuringian paragneisses taken up by the granite near the source level. The pale microgranular enclaves with igneous texture (PMEI) could be fragments of a yet-unknown granitic material or unmelted igneous material of an inhomogeneous source. The biotite-rich microgranular enclaves with igneous texture (BMEI) and the microgranular enclaves with polygonal texture (MEP) represent material which derives from the source region of the granite. The Kösseine granites represent an independent intrusion among the Fichtelgebirge granites formed by a combination of incomplete restite unmixing, assimilation and probably fractional crystallization in the course of magma formation, ascent and emplacement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00014648
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  • 9
    Electronic Resource
    Electronic Resource
    Kontinuierlicher und diskontinuierlicher Zonarbau in den Granaten der penninischen Gesteine der Zillertaler Alpen (Tirol/Österreich) (1976)
    Springer
    Mineralogy and petrology 23 (1976), S. 117-136 
    Details
    ISSN: 1438-1168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Summary In the Penninic gneisses, micaschists and amphibolites of the Zillertaler Alpen (Tyrol/Austria) the garnets show two types of zoning: a) a continuous bellshaped zoning, and b) a discontinuous zoning. The garnets with a continuous zoning have cores rich in MnO and CaO and rims rich in FeO and MgO. The differences in composition between cores and rims are greater in the garnets of the Greenschist facies than in those of the Amphibolite facies. Garnets with discontinuous zoning are found in the rocks of the Greinerschiefer series and in migmatic gneisses. These garnets show an abrupt compositional change from euhedral cores very rich in MnO and poor in CaO to marginal zones rich in CaO and FeO. The discontinous zoning is due to a two stage metamorphism of possibly Cretaceous to Tertiary age. The distribution coefficients for the mineral pair garnet/biotite are about 57 for MnO and 0.3 for MgO in the Greenschist facies and 6 for MnO and 0.4 for MgO in the Amphibolite facies.
    Notes: Zusammenfassung In den penninischen Gneisen, Glimmerschiefern und Amphiboliten der Zillertaler Alpen (Tirol/Österreich) treten Granate mit zwei Arten von Zonarbau auf: a) kontinuierlichem “glockenförmigen” und b) diskontinuierlichem “sprunghaften”. Die Granate mit kontinuierlichem Zonarbau sind im Kern MnO- und CaO-reich und im Rand FeO- und MgO-reich. Die Granate aus der Grünschieferfazies haben einen stärkeren Zonarbau als die der Amphibolitfazies. Die Granate mit diskontinuierlichem Zonarbau kommen in Gesteinen der Greinerschieferserie und in den gebänderten migmatischen Gneisen vor. Solche Granate zeigen eine sprunghafte Änderung ihrer chemischen Zusammensetzung an der Grenze zwischen dem idiomorphen Kern und dem Rand. Der Kern ist MnO-reich und CaO-arm, der Rand hingegen CaO- und FeO-reich. Dieser diskontinuerliche Zonarbau ist die Folge einer wahrscheinlich zweiaktigen kretazischen oder tertiären Metamorphose. Der Verteilungskoeffizient für das Mineralpaar Granat/Biotit ist in der Grünschieferfazies 57 für MnO und 0,3 für MgO. In der Amphibolitfazies ist er entsprechend 6 und 0,4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01081479
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  • 10
    Electronic Resource
    Electronic Resource
    Ein Vergleich der Ergebnisse von A. Bianchi und F. Karl über die granitischen Gesteine des Zillertales und des Großvenedigers (Hohe Tauern) (1960)
    Springer
    Mineralogy and petrology 7 (1960), S. 290-316 
    Details
    ISSN: 1438-1168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Zusammenfassung Es wurde in einem Vergleichsreferat zwischen den Untersuchungsergebnissen vonA. Bianchi (1934) undF. Karl (1959) an den granitischen Gesteinen des Zillertal- und Großvenedigerbereiches (Hohe Tauern) und dem Tonalitmassiv des Rieserferner gezeigt, daß sich die Beobachtungen und Teilergebnisse vonBianchi trotz unterschiedlicher genetischer Auswertung gut in das Gesamtbild vonKarl einordnen lassen. Wichtig ist dafür, daß die Mehraktigkeit der alpidischen Orogenese für die Beurteilung des Verhältnisses zwischen Kristallisation und Deformation berücksichtigt wird und daß aus der zusammengefaßten Gesteinsgruppe der “granodioritischen, schichtigen oder massigen Orthogneise mit normaler Biotit-reicher Facies” tonalitisierte Paragneise (nachKarl “Tonalitische Gneise”) abgetrennt werden. Für die petrochemischen Vergleiche wurden alle interessierenden AnalysenBianchis auf Kationoxydprozente (Eskola) verrechnet und in vergleichbaren Verhältniszahlen gegenübergestellt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01127918
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