GEOMORPHOLOGY OF THE PACAÁS NOVOS RANGE, SOUTHWESTERN AMAZONIA, BRAZIL: ONE EXAMPLE ON THE IMPORTANCE OF GEOMORPHOLOGICAL EVIDENCES TO THE RECONSTRUCTION OF QUATERNARY PALEOENVIRONMENTAL SCENARIOS IN AMAZONIA

Abstract

The geomorphology of the Pacaás Novos Range was surveyed. The study area is situated in the State of Rondonia, southwestern Amazonia, near the Brazil - Bolivia border. The range is formed by sedimentary Precambrian rocks and the piedmont area by Precambrian crystalline rocks of the Guaporé Shield. The occurrence of a thick saprolite mantle, detrital talus, pediments, duricrust formation, dissection and alluvial fans provide strong evidence that the morphogenetic systems changed drastically in this part of Amazonia during the Quaternary.