Abstract
The Salamangone deposit occurs in the Lourenco Gold District, Amapa. It is associated to Paleoproterozoic metamorphosed supracrustal rocks and a calc-alkaline complex. The deposit lies within a met aluminous to weakly peraluminous, calc-alkaline tonalitic- granodioritic pluton. The Au-mineralization consists of an epigenetic quartz-vein system, enriched in Au and As, and structurally controlled by a ductile-brittle shear zone. U-Pb zircon analyses of tonalite gave a crystallization age of 2.16 ± 0.13Ga, whereas Sm-Nd T model ages of tonalite and granodiorite range from 2.24 and 2.34Ga. a Nd (T) vary from +2.88 to +3.02. Additional whole rock Rb-Sr isocnron ages on granitoids yielded values in the range of 2.17 to 2.28Ga, with Sr 87 / 86 Sr initial ratio of 0.702. The isotopic data and geochemical signature of granitoids suggest that the Louren9o region, as well as the neighboring areas in French Guyana, represents a vast area largely floored by accreted juvenile arc terranes without evidence of Archean crust contamination, being related to the development of a calc-alkaline magmatic arc, which was produced within the Maroni-Itacaiunas Province, during a major Paleoproterozoic orogenic event.
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