The Mesoarchean Na-granitoids exposed in the Rio Maria domain, southeastern Amazonian craton, are represented by tonalite-trondhjemite and leucogranodiorite-granite suites. The 2.98-2.92 Ga tonalite-trondhjemites are the most voluminous rock type in the Rio Maria domain and host 2.86 Ga leucogranodiorite-granite plutons. These rocks share common geochemical characteristics, such as relatively high Al 2 O 3 and Na 2 O and low Yb and Y contents, as well as the behavior of the REE. However, based on an extensive geochemical data set, it is possible to show that the leucogranodiorite-granites have higher K 2 O, Ba, Sr, and Rb and lower CaO contents than the tonalite-trondhjemites. The latter are compositionally similar to typical tonalite-trondhjemite-granodiorite (TTG) series and probably originated from partial melting of garnet amphibolites, derived from tholeiitic rocks or from metabasalts of the Identidade greenstone belt, at pressure conditions suitable to produce high, medium, and low La/Yb tonalite-trondhjemite groups. The leucogranodiorite-granites show geochemical affinity with the Transitional TTG of the Yilgarn craton and are related to the Hybrid granitoid group. The ambiguous geochemical character of the Rio Maria leucogranodiorite-granite suite, which shares some characteristics that are typical of the tonalite-trondhjemite rocks and others more commonly observed in the sanukitoid suites, may be related to complex processes involving TTG and sanukitoid magmas. The discrimination of these two Na-granitoid groups helps us estimate the true volume of TTG magmatism in the Rio Maria domain and in understanding the dynamics of petrogenetic processes in the terrane at the end of the Archean.

This paper aims to present the results obtained by the integration and analysis of geophysical data and Digital Elevation Model (DEM) images as an important tool in geological mapping in an area located in the Rio Maria Granite-Greenstone Terrane (RMGGT), in the Central Amazonian Province (Tassinari & Macambira, 2004) or Carajás Province (Santos, 2003), southeastern Amazonian Craton, Xinguara area, southeastern Pará. The aerogammaspectrometric and aeromagnetometric data used for this study were acquired by the Brazil-Canada Geophysical Project (PGBC) and the digital elevation images by the Shuttle Radar Topographic Mission (SRTM). The integration and analysis of these data showed to be very useful for geological mapping, specially to distinguish the different lithologies and help to select key areas for more detailed verification during the field mapping. At the end of this study, it was elaborated a geological map for the selected area.

As informações geológicas da porção sul do Domínio Rio Maria, Província Carajás (sudeste do Cratón Amazônico), são escassas. Dados aerogeofísicos e de campo permitiram definir a assinatura aerogeofísica das unidades geológicas, identificar enxames de diques (NE-SW, NW-SE e N-S) e reconhecer distintos padrões estruturais (NE-SW, NW-SE e N-S e E-W) na porção sul do Domínio Rio Maria. Três grupos de granitoides foram distinguidos nessa região: 1) associação tonalítica-trondhjemítica; 2) leucomonzogranitos e; 3) leucogranodioritos. Observa-se aumento do conteúdo de SiO2, K2O e Rb e das razões alcáli-feldspato/plagioclásio, K2O/Na2O, FeOt/(FeOt + MgO), e decréscimo das proporções de TiO2, Al2O3, Fe2O3t,CaO, MgO, Sr e Zr no sentido grupo 1 → grupo 2. Os grupos 1 e 3 registram similaridades geoquímicas. No entanto, o grupo 1 exibe teores mais elevados de CaO e mais baixos de K2O e Rb em relação ao grupo 3. Essas rochas apresentam moderada a alta razão La/Yb e ausência de anomalia de európio. Já o grupo 2 mostra enriquecimento dos (ETRL) e moderado fracionamento dos (ETRP), com moderada a pronunciada anomalia negativa de Eu. O grupo 1 representa as rochas mais antigas do Tonalito Arco Verde (2,96 ± 0,02 Ga), enquanto as rochas dos grupos 2 e 3 mostram fortes analogias com os leucogranitos potássicos e com os leucomonzogranitos-granodioritos ricos em Ba e Sr do Domínio Rio Maria, respectivamente. A integração dos dados multifontes permite assumir que a granitogênese arqueana do Domínio Rio se estende por pelo menos 80 km a sul da cidade de Redenção, e as séries granitoides aflorantes nessa porção são análogas àquelas presentes na região de Pau D’Arco, Rio Maria, Bannach e Xinguara.