Unveiling the polyphasic evolution of the Neoarchean IOCG Salobo deposit, Carajás Mineral Province, Brazil : Insights from magnetite trace elements and sulfur isotopes
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| Автор: | |
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| Дата публікації: | 2021 |
| Інші автори: | , , |
| Формат: | Article |
| Мова: | eng |
| Джерело: | Repositório Institucional da UnB |
| Download full: | https://repositorio.unb.br/handle/10482/45124 https://doi.org/10.1016/j.oregeorev.2021.104572 https://orcid.org/0000-0001-8516-102X |
Резюме: | The Salobo iron oxide copper-gold (IOCG) deposit host an important Cu-mineralization of the Carajás Mineral Province. The ore is characterized by an association of (bornite-chalcocite-digenite) hosted by magnetite and biotite-garnet schists. These rocks record distinct stages of superimposed hydrothermal alteration and dynamic metamorphism. Three different occurrences of magnetite constitute the magnetite bodies: a pristine to inclusionpoor Mgt I; inclusion-rich magnetite-bearing breccia Mgt II, and the granoblastic-foliated Mgt III. In general, the magnetite types present a similar trace element composition with some variations in Si, Al, Mg and K indicating that the magnetite types share the same magmatic-hydrothermal origin with post-formation processes (dissolution/reprecipitation) recorded in Mgt III. In addition, sulfur isotope signatures for chalcopyrite (1.3–3.35‰), pyrrhotite (0.88–1.98‰), and pyrite (1.7–5.04‰) associated with magnetite I and II, are consistent with a magmatic-hydrothermal sulfur source at Salobo without/or minimal external sulfur contributions. Our data indicate that ore-forming Auids for Salobo ore could have undergone sulfur disproportionation processes during sulBde formation due to magnetite precipitation, which results in the classic IOCG mineral association of chalcopyrite + magnetite described for the Brst time in this contribution. Therefore, the main mineralization event in the Salobo deposit could be coeval with similar IOCG deposits in the Carajás Mineral Province related to the Neoarchean magmatism at ca. C.7 Ga. SubseDuent deformation and low-grade dynamic metamorphism related to reactivation of the Cinzento Shear Eone (ca. C.5 Ga) and A-type granite emplacement probably Paleoproterozoic in age resulted in remobilization-recrystallization of magnetite and Cu-sulBdes. |