Archean crustal sources for Paleoproterozoic tin-mineralized granites in the Carajás Province, SSE Pará, Brazil: Pb-Pb Geochronology and Nd isotope geochemistry

Abstract

Whole-rock and K-feldspar Pb, single zircon Pb-evaporation, and Nd whole-rock isotopic data are presented for granites of the Velho Guilherme intrusive suite and the volcanic rocks of the Uatumã Group in the Carajás Mineral Province, southern Pará, Brazil. Pb/Pb zircon ages of 1867/4 Ma, 1862/16 Ma, and 1866/3 Ma for the Antonio Vicente, Mocambo,and Rio Xingu granite massifs, respectively, show that the granites were emplaced at/1870 Ma.Pb/Pb whole-rock reference age of the Uatumã volcanic rocks, 1875/158 Ma, is comparable within the limits of the error. 1870 Ma thus represents the time of an important magmatic event in the eastern part of the Amazonian craton. Nd model ages of the granites (3.0/3.2 Ga) and volcanic rocks (2.9/3.1 Ga) and their strongly negative initial oNd values indicate that the magmas were derived from Mesoarchean rocks with a long crustal residence time. A mantle contribution cannot be completely ruled out,however