GEOLOGICAL RECONNAISSANCE OF THE CONTAMANA REGION, PERU
The Contamana region of eastern Peru includes part of the Cordillera Oriental of the Andes and the flat Amazon plain, cut by the Ucayali and Huallaga rivers. The area is of particular importance because it lies in the central regions of petroleum exploration programs. More than 6000 meters of Ordovician, Pennsylvanian, Jurassic (?), Cretaceous, and Tertiary rocks crops out. Most of this sequence is confined to the Cretaceous and Tertiary. The Cretaceous rocks show transgressive and regressive facies. The region was folded at the end of the Miocene and peneplaned by mid-Pliocene. There was subsequent epeirogenic movement of the whole region. A stratigraphic nomenclature applicable to all of northeastern Peru is proposed, and the type sections are described.