Caracterização petrológica de maciços pertencentes a Serra da Providência com base em dados litogeoquímicos, petrográficos e isotópicos (U-Pb e Lu-Hf) em zircão

Petrological characterization of Serra da Providência massifs based on lithogeochemical, petrographic and isotopic (U-Pb and Lu-Hf) data in zircon

Abstract

The Serra da Providencia intrusive suite (1.57 to 1.53 Ga), comprises the oldest rocks of rapakivi type-A magmatism, formed in the SW of the Amazonian craton associated with mineralization in Sn, Nb, Ta, W, and topaz a part of the Rondônia Tin Province. This work investigated the lithogeochemistry, U-Pb and Lu-Hf isotopes by LA-ICP-MS in zircon from the Serra da Providencia Suite composed of biotite-granite, amphibole-granite (both classified as intra-cratonic granites), ferroan type oxidized and pyroxene-granite defined as reduced magnesian and presents a calcic composition coherent with oceanic arc granites. The ages obtained for the samples from this Suite were 1557.7±8.4 My for the clinopyroxene-bearing granite, 1540 ±5.7 My, and 1573.7± 6.6 My for the amphibole-bearing facies samples, and 1525 ±5.6 My for a biotite-granite. TDM ages and εHf values define the heterogeneity of sources for the formation of the rocks in this Suite, showing that the pyroxene-bearing rock has a TDM age between 2.33 to 2.27 Gy and εHf (-9.6 to -7. 4) improbably formed from in a crustal Paleoproterozoic source. In contrast, the other rocks have a small proportion of crustal components as their source and a greater contribution from the mantle with ages of extraction from the Paleo to Mesoproterozoic.