Facies sedimentarias continentales del Paleógeno de las cuencas Ene y Pachitea, departamentos de Ucayali y Junín, Perú

Abstract

A recent stratigraphic, sedimentological and paleontological survey, in the Apurucayali River, Puerto Ocopa-Río Pangá and Huantashiri creeks, have allowed to recognize and detailed the Paleogene units of the Ene and Pachitea basins, in the departments of Junín and Ucayali, in the center-eastern of Perú. The aim of this contribution is to make known the results of these studies and to discuss the sedimentary processes and environments that lead up in this region during Paleogene times. The methodology was based on the survey of sedimentological profiles of 1:100, characterization of sand bodies and pelitic packages, recognition of organic sedimentary structures (traces fossils and rhizoliths), record and identification of paleontological content, observation of paleoecological and taphonomic aspects, identification of sedimentary processes and interpretation of possible paleoenvironments and depositacional systems. The Paleogene lithostratigraphic units recorded from base to top are the Cachiyacu, Huchpayacu, Yahuarango, Pozo and Chambira formations. On the base of the sedimentary facies and the paleontological record, a continental fluvial-lake deposition system has been recognized, while lightly paleoclimatic changes have been occurring during their sedimentation.Finally, it is important to note that i) the development of the Pozo Fm is identified for the first time in these basins, which was in doubt, and ii) pyroclastic material of Eocene age (40-42 Ma) were found in the lower section of the ChambiraFm., in the three localities.