Abstract
Abstract Alta Floresta Gold Province occurs in the center-south portion of the Amazon Craton. Trairao gold deposit, which is located in the Alta Floresta Gold Province, is hosted by 1878 to 1854 Ma arc-related granites. Two important Au deposits take place in the region, the Trairao and Chumbo Grosso, which are structurally controlled by N80°W/S80°E trending lineament and associated with quartz veins and disseminated sulfides in a strong phyllic alteration zone of the host granite. Hydrothermal monazite grains formed during the Au mineralization event occur as fine anhedral crystals filling fractures or as isolated grains associated with Ag, Au, molybdenite, barite, pyrite, galena, and sphalerite. The hydrothermal monazite grains contain very low U, relatively low Th, and moderate Nd and La contents. SHRIMP U-Th-Pb dating of these crystals yielded an age of 1798 ± 12 Ma for Trairao and 1805 ± 22 Ma for Chumbo Grosso Au-deposits, whereas magmatic zircon grains of the granitic host rocks yielded an age of 1854 ± 8 Ma. The ages obtained in this paper are similar to those reported by Assis (2015), who studied Pe Quente (Re-Os in molybdenite, 1792 ± 9 Ma and 1784 ± 11) and Francisco deposits (40Ar-39Ar ages from sericitic halo: 1779 ± 6.2 and 1777 ± 6.3 Ma). Serrato et al. (2014) acquired Re-Os dating in pyrite and molybdenite from Juruena gold deposit. The results show isochronous ages at 1786 ± 1 Ma, with a model age at 1787 ± 3.2 Ma, suggesting a major Statherian gold metallogenic event at the Alta Floresta Gold Province region. Regional fluids-flow has a close relationship with the generation and concentration of several important economic deposits in the Eastern border of Alta Floresta Gold Province, including Pe Quente, Francisco, Juruena, Chumbo Grosso, and Trairao Au-deposits.
Highlights
The Amazon Craton (AC) was formerly considered a large Archean platform that underwent reworking and reactivation during the Proterozoic, with expressive anorogenic felsic magmatism (Amaral 1974, Almeida et al 1981). Santos et al (2004) recognized four domains within the Tapajós — Parima Province: Parima, Uaimiri, Tapajós, and Peixoto de Azevedo (Fig. 1)
Several gold and copper-gold deposits are found within the Proterozoic Tapajós and Peixoto de Azevedo domains, which are marked by successive magmatic arcs with steady‐state and flare-up stages to Sierra Nevada Batholith stages presented by Paterson and Ducea (2015)
We present the mineral chemistry, coupled with U-Pb isotopes and petrographic determinations from quartz breccia associated with gold deposit, to investigate the timing responsible for this hydrothermal regional event that took place at the Alta Floresta Gold Province (AFGP)
Summary
The Amazon Craton (AC) was formerly considered a large Archean platform that underwent reworking and reactivation during the Proterozoic, with expressive anorogenic felsic magmatism (Amaral 1974, Almeida et al 1981). Santos et al (2004) recognized four domains within the Tapajós — Parima Province: Parima, Uaimiri, Tapajós, and Peixoto de Azevedo (Fig. 1). Santos et al (2004) recognized four domains within the Tapajós — Parima Province: Parima, Uaimiri, Tapajós, and Peixoto de Azevedo (Fig. 1). This study was carried out in the Southern Peixoto de Azevedo Domain, which is part of Alta Floresta Gold Province (AFGP). The economic importance of Tapajós and Peixoto de Azevedo Domains motivated a regional mapping. Exploration by mining companies resulted in thousands of surfaces and drill core samples for study (Santos et al 2004). Several gold and copper-gold deposits are found within the Proterozoic Tapajós and Peixoto de Azevedo domains, which are marked by successive magmatic arcs with steady‐state and flare-up stages to Sierra Nevada Batholith stages presented by Paterson and Ducea (2015)
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