TURBIDITOS E A GLACIAÇÃO DO FINAL DO PROTEROZOICO SUPERIOR NO CINTURÃO PARAGUAI, MATO GROSSO

Abstract

URBIDITES AND THE UPPER PROTEROZOIC GLACIATION IN THE PARAGUAI FOLDED BELT, MATO GROSSO. The Puga and BAuxi formations do not show an unconformable contact with the Cuiabá Group but there is a gradual change from the glaciomarine environment, partially represented by the Puga formation, to turbidites of the Cuiabá Group. Turbidity currents might have generated due to landsliding of the glacial deposits over the Amazonic Craton border. Diamictite and residemented conglomerates associated with turbidity flows are considered to belong to a glaciomarine facies produced by sub-aqueous gravity flows. The distal facies is made up of fine grained sediments deposited from suspension. Limestones of the Araras formation are thought to be deposited after the glaciation. This formation, near Corumbá, bears Ediacaran type of faune, suggesting an age Vendian for the sedimentation. The sedimentary and metassedimentary units that belong to the Paraguai fold belt are affected by the Brasiliano Cycle, which developed in the region during the Upper Proterozoic and the Fanerozoic boundary. A few post-tectonic granitic plutons of about 400 Ma age are observed in the middle part of the belt.