GEOLOGIC EVOLUTION OF THE PARAGUAY BELT IN NOVA XAVANTINA AREA, EASTERN MATO GROSSO STATE, BRAZIL

Abstract

Geological mapping conducted in the eastern portion of the Paraguai Belt, in Nova Xavantina region, Mato Grosso state, Brazil, allowed the individualization of four informal lithostratigraphic units: (i) Bacuri, composed of iron formations and banded metacherts; (ii) Antártico defined by lithotypes arranged in cycles of heterolithic facies of quartz phyllite, marble, calciferous phyllite, metarkose, metaconglomerate, metasiltite and metagreywacke, exhibiting gradational bedding, associated with plane-parallel, crushed and convoluted laminations, as well as stratifications in lenses, which reflect a deposition controlled by mixed processes (waves and tides); (iii) Touro Branco, represented by metarenite and quartzite with great compositional maturity, planar and cross-tabular cross-stratifications of low angle, besides wavy and erosion marks; (iv) Fazenda Cachoeirinha, marked by homogeneous laminated phyllites. The information collected suggests that these rocks were deposited in a transitional marine environment, formed in a transgressive mega cycle that ends by a progression in a distal marine environment, which towards the top and laterally becomes shallower, facing the coastal plain followed by new regression.