Formation of ore minerals in metamorphic rocks of the German continental deep drilling site (KTB)
| Autor: | E. E. Horn, H. J. Behr, Agnes Kontny, G. Zulauf, Günther Friedrich, H. de Wall, P. Möller |
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| Přispěvatelé: | 4.3 Organic Geochemistry, 4.0 Chemistry and Material Cycles, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum |
| Předmět: |
Atmospheric Science
Geochemistry Soil Science Mineralogy 550 - Earth sciences Aquatic Science engineering.material Oceanography chemistry.chemical_compound Geochemistry and Petrology Mineral redox buffer Titanite Earth and Planetary Sciences (miscellaneous) Paragenesis Pyrrhotite Metamorphic facies Earth-Surface Processes Water Science and Technology Magnetite Mineral Ecology Paleontology Forestry Geophysics chemistry Space and Planetary Science engineering Ilmenite Geology |
| Zdroj: | Scopus-Elsevier Journal of Geophysical Research |
| Popis: | The German Continental Deep Drilling Program (KTB) drilled a 9.1 km deep profile through amphibolite facies metamorphic rocks and reached in situ temperatures of 265°C. Each lithologic unit is characterized by typical ore mineral assemblages related to the regional metamorphic conditions. Paragneisses contain pyrrhotite + rutile + ilmenite ± graphite, metabasic units bear ilmenite + rutile + pyrrhotite ± pyrite, and additionally, the so-called variegated units yield pyrrhotite + titanite assemblages. In the latter unit, magnetite + ilmenite + rutile + titanite assemblages related to the lower amphibolite facies breakdown of ilmenite-hematite solid solution also occur locally. Retrograde hydrothermal mineralization which commenced during Upper Carboniferous times is characterized by the following geochemical conditions: (1) low saline Na-K-Mg-Cl fluids with sulfur and oxygen fugacities at the pyrite-pyrrhotite buffer and temperatures of 400–500°C, (2) fluids with CO2, CH4±N2, andpH, Eh, sulfur, and oxygen fugacity in the stability field of graphite + pyrite at temperatures of 280–350° and (3) moderate to high saline Ca-Na-Cl fluids with CH4+ N2; sulfur and oxygen fugacity are in the stability field of pyrrhotite at temperatures |
| Databáze: | OpenAIRE |
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