| Autor: |
Jingwen Mao, Bierlein, Frank P., Munhá, J., Relvas, J. M. R. S., Barriga, F. J. A. S., Conceição, P., Jorge, R. C. G. S., Mathur, R., Ruiz, J., Tassinari, C. C. G. |
| Zdroj: |
Mineral Deposit Research: Meeting the Global Challenge; 2005, p663-666, 4p |
| Abstrakt: |
New Re and Os analyses of pyrites from Aljustrel, Lagoa Salgada and Neves-Corvo deposits yield concentrations that are similar to those previously reported for the Rio Tinto and Tharsis deposits, all at the Iberian Pyrite Belt. Osmium contents in IPB pyrites increase from the deeper stockwork zones towards the upper massive sulphides. Pyrite samples from IPB sulphide orebodies plot on a major 187Re/188Os-187Os/188O linear array, yielding an age of 359±26 Ma and an initial 187Os/188O ratio of ca. 0.57. Five samples from Neves-Corvo sulphide-rich stockwork ores yield an age of 358 ±29 Ma and an initial 187Os/188O ratio of 0.49 ±0.07, in accord with palynological and isotopic age constraints for ore formation at the IPB. Pyrites from Neves-Corvo copper-tin ores have Re/Os ratios and osmium concentrations that are similar to those in pyrites from sulphide-rich stockwork ores; however, their highly radiogenic initial 187Os/188O ratios (4.89-7.85, if preserving original isotope system-atics) preclude derivation from the same sources as the remaining IPB sulphides. The overall Re-Os geochemical data conform to previous Sr, Nd and Pb isotopic studies supporting multiple sources for IPB metallogenesis. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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