Integração de dados petrográficos, geoquímicos e geocronológicos dos diques do Domínio Rio Maria, Província Carajás

Abstract

The Domain Rio Maria integrates the southern portion of the Carajás Province, Amazon Craton. It is composed of Archean granitoids formed between of 2.98 to 2.87 Ga and similar with the typical series of granitoids present in other Archean terrains. At about 1.88 Ga, the region of Rio Maria domain was the scene of an A-type granite magmatism, represented by granite bodies of the Jamon suite and by coeval felsic and mafic dikes. This work involves the integration of geological data from the dikes of the Rio Maria domain, located in Rio Maria, Bannack, Água Azul do Norte, and Tucumã regions. Additionally, a comparison was made between the dikes of the Rio Maria domain and those studied in the Carajás domain. This study allowed the petrographic, geochemical and geochronological characterization that served as the basis for the discussion of the petrogenetic and tectonic processes and, also, to figure out whether the dikes of the different areas of the Domain Rio Maria are similar or different from the dikes of the Carajás domain. The dikes present tabular forms in subvertical bodies of 10 to 20-metre-thick, sometimes reaching 30 metres, and in some cases reaching up to 2 km. These dikes cut the Archean units and, locally, the Paleoproterozoic granites. Based on petrographic studies, it was possible to separate them into three main groups: mafic dikes (andesites of basalt, basalt and diabase), intermediate dikes (andesite basalt, andesites and dacites) and felsic dikes (rhyolites and alkali-feldspar rhyolite). The chemical signature, structural pattern, and textural aspects of the different lithologies of the subvulcanism of both Rio Maria and Carajás domains show strong evidence that these rocks are non-cogenetic and probably represent more of a tectono-magmatic post-Archean event. The geochronological data allow locating the dikes of the Rio Maria Domain in the Proterozoic, suggesting that at least some of these dikes are coeval with the A-type magmatism.