Neoarchean magmatism in the southeastern Amazonian Craton, Brazil: Petrography, geochemistry and tectonic significance of basalts from the Carajás Basin

Serra Sul diamictite of the Carajás Basin (Brazil): A Paleoproterozoic glaciation on the Amazonian craton

“…Compared to the Neoproterozoic Sturtian glaciation, in which iron formation was deposited simultaneously with diamictite in sub-ice shelf settings (Lechte and Wallace, 2016), the deposition of diamictite in the Serra Sul system was completely decoupled from the deposition of the BIF. Although the expressive rift-related volcanism of the Carajás Basin represented by the Grão-Pará Group (Olszewski et al, 1989;Martins et al, 2017) may be related to the breakup of the southern supercontinent at the end of the Archean, and may have also been one of the triggers of Serra Sul glaciation, this volcanic…”

Geochemical distribution and threshold values determination of heavy metals in stream water in the sub-basins of Vermelho and Sororó rivers, Itacaiúnas River watershed, Eastern Amazon, Brazil

“…In the Carajás Province, the main units are Mesoarchean calc-alkaline granites, tonalites and trondhjemites with subordinate gneisses and migmatites and local remnants of greenstone belts (Machado et al 1991, Feio et al 2013, Moreto et al 2014. The granitoid basement is overlain by the Neoarchean Itacaiúnas Supergroup, which is represented by mafic-felsic volcanic sequences of the Grão Pará (Zucchetti & Lobato 2004, Martins et al 2017, and Rio Novo groups (Gibbs et al 1986, Docegeo 1988, Machado et al 1991, Vasquez et al 2008. These units are crosscut by Archean syntectonic A-type like granitoids (Huhn et al 1999, Barros et al 2001, Sardinha et al 2006, Feio et al 2012, layered mafic-ultramafic rocks (Machado et al 1991, Vasquez et al 2008, Teixeira et al 2015, and Paleoproterozoic anorogenic A-type granitic plutons .…”

Archean crust and metallogenic zones in the Amazonian Craton sensed by satellite gravity data

“…In this way, exotic and Rhyacian juvenile rocks (e. g. <2.4 to 2.0 Ga felsic intrusive rocks 18,50 ) concentrated along the edge of the Carajás crust to the north (Figs 4a,b, 5). Furthermore, we constrain the continental interior for the formation of the Carajás Basin as an intracontinental rift, as previously argued 44 . The high-density bodies on the infrastructure of the Rio Maria and Carajás crusts are interpreted as related to the Archean poly-phase basic/ultra-basic magmatism, likely forming the basal parts of the magmatic systems.…”

“…That is of particular interest given the undisclosed settings of high-temperature crystallization circa 2.5 and 2.4 Ga 36 within Mesoarchean gneisses along the Cinzento shear system. A plausible situation for a previous separation of the Carajás and proto-Bacajá domains within the Carajás crust would be that of continental rifting associated with the formation of the Carajás basin 44 . However, in the absence of a detailed description of the gneissic basement and analysis of protolith age inventory to the South of the Bacajá domain, we cannot ascribe a precise scenario.

Figure 5Interpreted crustal framework for the Carajás Mineral Province given by extended Archean lithosphere as interpreted from geophysical constraints on the crustal architecture and geochronology.

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“…Their formation is inferred to relate to processes involved in the consumption of oceanic crust during the Mesoarchean and Paleoproterozoic in the Rio Maria and Bacajá domains, respectively. Current models for the mineral systems in the CMP 30,35 imply structural (re-) activations within a stable plate interior 30,33,44 or proximity to zones of crust consumption 31 . However, at the moment, there are no clues to the lithosphere geometry in the CMP and the plausible extent of the envisaged continental plates.…”