Paleoproterozoic volcanic centers of the São Félix do Xingu region, Amazonian craton, Brazil: Hydrothermal alteration and metallogenetic potential

• Published in: Journal of volcanology and geothermal research 2016-06, Vol.320, p.75-87
• Main Authors: da Cruz, Raquel Souza, Fernandes, Carlos Marcello Dias, Villas, Raimundo Netuno Nobre, Juliani, Caetano, Monteiro, Lena Virgínia Soares, Lagler, Bruno, Misas, Carlos Mario Echeverri
• Format: Article
• Language: English
• Subjects: Alterations; Carajás Mineral Province; Carbonates; Chlorites; Cratons; Formations; Fracture-controlled style; Geothermal; Gold occurrence; Hematite; Hydrothermal alteration; Paleoproterozoic volcano-plutonism; Quartz
• ISSN: 0377-0273; 1872-6097
• DOI: 10.1016/j.jvolgeores.2016.04.023

Geological, petrographic, scanning electron microscopy, and X-ray diffraction studies revealed hydrothermalized lithotypes evidenced by overprinted zones of potassic, propylitic, sericitic, and intermediate argillic alterations types, with pervasive and fracture-controlled styles, in Paleoproterozoic volcano-plutonic units of the São Félix do Xingu region, Amazonian craton, northern Brazil. The Sobreiro Formation presents propylitic (epidote+chlorite+carbonate+clinozoisite+sericite+quartz±albite±hematite±pyrite), sericitic (sericite+quartz+carbonate), and potassic (potassic feldspar+hematite) alterations. The prehnite–pumpellyite pair that is common in geothermal fields also occurs in this unit. The Santa Rosa Formation shows mainly potassic (biotite+microcline±magnetite), sericitic (sericite+quartz+carbonate±chlorite±gold), and intermediate argillic (montmorillonite+kaolinite/halloysite+illite) alterations. These findings strongly suggest the involvement of magma-sourced and meteoric fluids and draw attention to the metallogenetic potential of these volcanic units for Paleoproterozoic epithermal and rare and base metal porphyry-type mineralizations, similar to those already identified in other portions of the Amazonian craton. •Hypogene hydrothermal alterations zones related to volcanic framework.•Detailed petrography and related gold and base metals occurrence•Characterization of the hydrothermal minerals with SEM and X-ray techniques•Implications for the Paleoproterozoic volcano–plutonism of the Amazonian Craton