Geological knowledge advances on the Alto Rio Negro region, northwestern Amazonian Craton, Brazil: a review

Abstract

This paper presents a literature review of the geology of the Alto Rio Negro region, located in northwestern Brazil. Firstly, we summarize the Amazonian Craton tectonic models and how the study area fits in these different tectonic models. The aim is to organize the literature data and better guide the consultation for new studies. The first geological reports about the Alto Rio Negro are from the Mid-19th century, when the British naturalist Alfred Russel Wallace travels to this country and, since then, long periods of scientific production absence occur. However, after the RADAMBRASIL Project in the 1970s, there was a significant research advance. Recent publications reveal a complex tectonic evolution, with three events that mark periods of generation and reworking of the Proterozoic basement. Two Paleoproterozoic magmatic arc systems generated the geological basement. The Calymmian collision of these terrains produced a large volume of crustal granites, in addition to pre-, and post-tectonic granites. A crustal reworking period (1.4-1.1 Ga) reactivated the basement structures and, possibly, generated the Ectasian carbonatitic intrusions. There are many difficulties to access this region, so the literature data are of great value and provide a background for new studies. The lack of more detailed geological maps covering the Alto Rio Negro region is the main obstacle. Still, it offers a fertile research field for geologists interested in contributing to diverse research fields of Geology focusing on the Amazonian Craton.

Keywords

• Alto Rio Negro
• Amazonian Craton
• Precambrian
• Geochronological provinces
• Guiana Shield