Abstract
The Tapajos Gold Province, central portion of the Amazonian Craton, is one of the main metallogenic provinces in Brazil, but lack geological studies at an appropriate scale in its southeastern portion. Fieldwork, petrography, and high-resolution airborne geophysics (magnetometry and gamma spectrometry) allowed us to produce a new map at the 1:100,000 scale. In this study, we identified two new geological units: (1) the volcanic and pyroclastic rocks of the Vila Riozinho Formation, previously attributed to the Iriri Group, including a newly described facies of this formation, which comprises a group of rocks with the highest magnetic contents of the study area, and (2) the Serra Alkali Feldspar Granite, which intruded into the Vila Riozinho Formation. Based on available geochronological information these units can be associated to a volcano-plutonic event that occurred in the Orosirian period, at about 1.98 Ga. In addition, our work allowed us to define better the areas of occurrence of other units. The Parauari Intrusive Suite and Iriri Group areas were strongly reduced, whereas the areas of the Creporizao Intrusive Suite and of the Novo Progresso Formation were increased.
Highlights
We identified two new geological units: (1) the volcanic and pyroclastic rocks of the Vila Riozinho Formation, previously attributed to the Iriri Group, including a newly described facies of this formation, which comprises a group of rocks with the highest magnetic contents of the study area, and (2) the Serra Alkali Feldspar Granite, which intruded into the Vila Riozinho Formation
The Tapajós Gold Province (TGP), which is basically synonymous of Tapajós Domain (Faraco et al 1997), is located in the south-central portion of the Amazonian Craton (Fig. 1) and is considered one of the main metallogenic provinces of Brazil
U-Pb LA-ICP-MS data in detrital zircon from a lithic arenite show two well-defined peaks at 1846 and 1968 Ma, and statistically secondary peaks. These results indicate that surrounding Orosirian rocks from the Tapajós Gold Province and Iriri-Xingu Domain, and from the Rondonia-Juruena Province were probably the main sources for the sediments
Summary
The Tapajós Gold Province (TGP), which is basically synonymous of Tapajós Domain (Faraco et al 1997), is located in the south-central portion of the Amazonian Craton (Fig. 1) and is considered one of the main metallogenic provinces of Brazil. Several issues regarding the TGP are still pending, including the limits with adjacent provinces or domains, the tectonic setting in which formed the volcano-plutonic units and the metallogenic evolution (e.g., Lamarão et al 2002; Vasquez et al 2017; Juliani et al 2013; Tokashiki et al 2015; Borgo et al 2017; Fraga et al 2017; Carneiro et al 2018; Klein et al 2012, 2017, 2018) Another issue is the scarcity of geological maps in suitable scales for certain parts of the TGP, which is the case of its southeastern sector, where maps are available only at the 1: 1,000,000 scale (Fig. 2, Vasquez and Rosa-Costa 2008), and produced by regional integration and satellite image interpretation. The host rocks for the hydrothermal deposits are felsic volcanic and volcanoclastic rocks and granitoids from uncertain stratigraphic units
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