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.
Highlights
The Amazon is a territory with a continental dimension, covered by a dense equatorial forest where there are relatively low human occupation and few access roads, making field research activities difficult
A more comprehensive geological recognition of this area dates from the 1970s, when the Brazilian government yielded remote sensing images and funded small-scale mapping (RADAMBRASIL Project)
The Tunuí Group comprises the low-grade metasedimentary successions of the western Alto Rio Negro region (e.g. Tunuí, Caparro, Macaco, Serrinha, and Traíras ranges) that were grouped in Tunuí-Caparro Lithofacies, in addition to paragneisses and migmatites grouped in the Taiuaçu-Cauera Lithofacies (Almeida 2006)
Summary
The Amazon is a territory with a continental dimension, covered by a dense equatorial forest where there are relatively low human occupation and few access roads, making field research activities difficult. In more remote areas, geological knowledge is still at an embryonic level (e.g. Alto Rio Negro - Amazonas state, Iriri-Xingu region - Pará state, and Tumucumaque - Amapá state). The first geological data of the Amazon date from the Mid19th century (Wallace 1853). On this occasion, the naturalist Alfred Russel Wallace carried out a pioneering expedition that reached the Alto Rio Negro region, the focus area of this review article. This literature review paper will unravel geological knowledge evolution in the Alto Rio Negro region, starting from the first expedition in the 19th century to the most recent research, consolidated until 2021. Mendes et al - JGSB 2021, 4 (3), 209 - 222 continuity to southern Colombia and Venezuela, this work comprises only Brazilian data, considering the significant difference in knowledge stage and geological nomenclature
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