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Thallium geochemistry in the metamorphic Lengenbach sulfide deposit, Switzerland: Thallium-isotope fractionation in a sulfide melt

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Published/Copyright: April 23, 2014
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American Mineralogist
From the journal American Mineralogist Volume 99 Issue 4

Abstract

The Lengenbach (Switzerland) Pb-As-Tl-Zn deposit was formed from a sulfide melt at about 500 °C during Alpine metamorphism, but details on its formation and especially the source of the metals are still under debate. In this study we present two sample sets to address these questions:

(1) MC-ICP-MS analyses of thallium isotopes in sulfides, sulfosalts, and melt inclusions from the Alpine metamorphic Lengenbach deposit in the Binn Valley of Switzerland, the non-metamorphic Wiesloch Mississippi Valley-type deposit in Southern Germany, and the Cu- and As-rich mineralization at Pizzo Cervandone about 2 km SW of the Lengenbach deposit, which has been discussed as potential source of the Lengenbach metals.

(2) LA-ICP-MS analyses of micas from the Lengenbach deposit and surrounding country rocks between the deposit and the Pizzo Cervandone to trace potential metal-bearing fluid pathways. We found that Tl isotope compositions expressed as ε205Tl values in all investigated samples range from -4.1 ± 0.5 to +1.9 ± 0.5. The whole variation can be seen in the Lengenbach deposit alone, which hence records considerable fractionation even during high-temperature processes involving a sulfide melt. This large range of ε205Tl is thought to be caused by nuclear volume-dependent fractionation. Interestingly, the common fahlores at Lengenbach behave differently from all other investigated sulfosalts: based on their heavy isotopic composition together with a low As/S-ratio, they do not seem to be crystallized from the sulfide melt, but are interpreted to have formed from hydrothermal fluids enriched in the heavy Tl isotopes. Although As mobilization in the gneisses and dolomites surrounding the Lengenbach deposit is evident based on secondary arsenites, no traces of such a country rock fluid could be found in fissure micas at Lengenbach. Hence, considerations involving K/Rb, Rb/Tl, As/S, and Pb/Tl ratios in the sulfides and micas imply that the element enrichment in the Lengenbach deposit is either pre-Alpine or related to peak metamorphism, but occurred definitely before mica growth at Lengenbach.

Keywords : Sulfide melt; thallium isotopes; metal sources; sulfosalts
Published Online: 2014-4-23
Published in Print: 2014-4-1

© 2014 by Walter de Gruyter Berlin/Boston

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  1. New data on lunar magmatic processes
  2. Thermodynamic approach provides insights into the aging process of biological apatite
  3. Effects of chemical composition and temperature on transport properties of silica-rich glasses and melts
  4. Speciation of and D/H partitioning between fluids and melts in silicate-D-O-H-C-N systems determined in-situ at upper mantle temperatures, pressures, and redox conditions
  5. Effect of oxalate and pH on chrysotile dissolution at 25 °C: An experimental study
  6. Gabbroic Shergottite Northwest Africa 6963: An intrusive sample of Mars
  7. Césarferreiraite, Fe2+Fe23+(AsO4)2(OH)2·8H2O, from Eduardo mine, Conselheiro Pena, Minas Gerais, Brazil: Second arsenate in the laueite mineral group
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  20. In-situ infrared spectra of hydroxyl in wadsleyite and ringwoodite at high pressure and high temperature
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  22. A calorimetric and thermodynamic investigation of the synthetic analogs of cobaltomenite, CoSeO3·2H2O, and ahlfeldite, NiSeO3·2H2O
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  24. Pressure-induced phase transitions in coesite
  25. Qingsongite, natural cubic boron nitride: The first boron mineral from the Earth’s mantle
  26. Phase relations in the system FeCO3-CaCO3 at 6 GPa and 900–1700 °C and its relation to the system CaCO3-FeCO3-MgCO3
  27. In-situ high-temperature emissivity spectra and thermal expansion of C2/c pyroxenes: Implications for the surface of Mercury
  28. Thallium geochemistry in the metamorphic Lengenbach sulfide deposit, Switzerland: Thallium-isotope fractionation in a sulfide melt
  29. Fluorowardite, NaAl3(PO4)2(OH)2F2·2H2O, the fluorine analog of wardite from the Silver Coin mine, Valmy, Nevada
  30. Correianevesite, Fe2+Mn22+(PO4)2·3H2O, a new reddingite-group mineral from the Cigana mine, Conselheiro Pena, Minas Gerais, Brazil
  31. Structural complexity of lead silicates: Crystal structure of Pb21[Si7O22]2[Si4O13] and its comparison to hyttsjöite
  32. A high-resolution powder neutron diffraction study of the crystal structure of neighborite (NaMgF3) between 9 and 440 K
  33. Geothermometric study of Cr-spinels of peridotite mantle xenoliths from northern Victoria Land (Antarctica)
  34. Crystal chemistry of the ulvöspinel-qandilite series
  35. Quantitative models linking igneous amphibole composition with magma Cl and OH content
  36. Chromium solubility in perovskite at high pressure: The structure of (Mg1–xCrx)(Si1–xCrx)O3 (with x = 0.07) synthesized at 23 GPa and 1600 °C
  37. New Mineral Names
  38. Errata
https://doi.org/10.2138/am.2014.4591
Keywords for this article
Sulfide melt; thallium isotopes; metal sources; sulfosalts

Articles in the same Issue

  1. New data on lunar magmatic processes
  2. Thermodynamic approach provides insights into the aging process of biological apatite
  3. Effects of chemical composition and temperature on transport properties of silica-rich glasses and melts
  4. Speciation of and D/H partitioning between fluids and melts in silicate-D-O-H-C-N systems determined in-situ at upper mantle temperatures, pressures, and redox conditions
  5. Effect of oxalate and pH on chrysotile dissolution at 25 °C: An experimental study
  6. Gabbroic Shergottite Northwest Africa 6963: An intrusive sample of Mars
  7. Césarferreiraite, Fe2+Fe23+(AsO4)2(OH)2·8H2O, from Eduardo mine, Conselheiro Pena, Minas Gerais, Brazil: Second arsenate in the laueite mineral group
  8. Atomic structure and formation mechanism of (101) rutile twins from Diamantina (Brazil)
  9. Mathesiusite, K5(UO2)4(SO4)4(VO5)(H2O)4, a new uranyl vanadate-sulfate from Jáchymov, Czech Republic
  10. Comparison of metal enrichment in pyrite framboids from a metal-enriched and metal-poor estuary
  11. Chemistry of bone mineral, based on the hypermineralized rostrum of the beaked whale Mesoplodon densirostris
  12. Allendeite (Sc4Zr3O12) and hexamolybdenum (Mo,Ru,Fe), two new minerals from an ultrarefractory inclusion from the Allende meteorite
  13. Hutcheonite, Ca3Ti2(SiAl2)O12, a new garnet mineral from the Allende meteorite: An alteration phase in a Ca-Al-rich inclusion
  14. Infrared absorption spectroscopy of SiO2-moganite
  15. Kaolinite transformation into dickite during burial diagenesis
  16. Effect of clays and metal containers in retaining Sm3+ and ZrO2+ and the process of reversibility
  17. Solid solutions and phase transitions in (Ca,M2+)M2+Si2O6 pyroxenes (M2+ = Co, Fe, Mg)
  18. Further complexities of the 10 Å phase revealed by infrared spectroscopy and X-ray diffraction
  19. Solid phases of FeSi to 47 GPa and 2800 K: New data
  20. In-situ infrared spectra of hydroxyl in wadsleyite and ringwoodite at high pressure and high temperature
  21. Experimental and infrared characterization of the miscibility gap along the tremoliteglaucophane join
  22. A calorimetric and thermodynamic investigation of the synthetic analogs of cobaltomenite, CoSeO3·2H2O, and ahlfeldite, NiSeO3·2H2O
  23. Arsenate partitioning from ferrihydrite to hematite: Spectroscopic evidence
  24. Pressure-induced phase transitions in coesite
  25. Qingsongite, natural cubic boron nitride: The first boron mineral from the Earth’s mantle
  26. Phase relations in the system FeCO3-CaCO3 at 6 GPa and 900–1700 °C and its relation to the system CaCO3-FeCO3-MgCO3
  27. In-situ high-temperature emissivity spectra and thermal expansion of C2/c pyroxenes: Implications for the surface of Mercury
  28. Thallium geochemistry in the metamorphic Lengenbach sulfide deposit, Switzerland: Thallium-isotope fractionation in a sulfide melt
  29. Fluorowardite, NaAl3(PO4)2(OH)2F2·2H2O, the fluorine analog of wardite from the Silver Coin mine, Valmy, Nevada
  30. Correianevesite, Fe2+Mn22+(PO4)2·3H2O, a new reddingite-group mineral from the Cigana mine, Conselheiro Pena, Minas Gerais, Brazil
  31. Structural complexity of lead silicates: Crystal structure of Pb21[Si7O22]2[Si4O13] and its comparison to hyttsjöite
  32. A high-resolution powder neutron diffraction study of the crystal structure of neighborite (NaMgF3) between 9 and 440 K
  33. Geothermometric study of Cr-spinels of peridotite mantle xenoliths from northern Victoria Land (Antarctica)
  34. Crystal chemistry of the ulvöspinel-qandilite series
  35. Quantitative models linking igneous amphibole composition with magma Cl and OH content
  36. Chromium solubility in perovskite at high pressure: The structure of (Mg1–xCrx)(Si1–xCrx)O3 (with x = 0.07) synthesized at 23 GPa and 1600 °C
  37. New Mineral Names
  38. Errata
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