Análisis de la estratigrafía del Neógeno de la cuenca Latacunga-Ambato, secciones en los valles del río Nagsiche y río Yanayacu

Abstract

The Latacunga-Ambato Basin located in the center of the IV of Ecuador. In the present work a tectonoestratigraphic and geomorphological study is carried out, synthesized in two sections that record the deposition of the eastern (Yanayacu river) and western (Nagsiche river) of the Basin. Field work, tectono-stratigraphic, structural and petrographic analysis determined that in the Basin it occurred: Deposit of the Pisayambo and Zumbahua Formations on the edges of the Cordillera Real and Occidental respectively. Subsequently, Latacunga Fm is deposited composed by a Volcannosedimentary Unit at the base and the Fluvio - Lacustrine Unit at the top. Above the Latacunga Fm. it deposited the pre-Chalupas Volcanic, unit not described before. The Chalupas Ignimbrite is deposited over them. The deformations indicate sinsedmentary tectonic compression after the accumulation of the Latacunga Formation and prior to the accumulation of the Chalupas Ignimbrite (0.2 Ma) without visible deformation. In addition, the first vertebrate fossil is recorded in the Fm. Latacunga, a horn and cervical vertebra of a deer (Cervidae aff. Hippocamelus). Geomorphological analysis of hypsometric curves denotes the presence of recent deformation in the area in Pleistocene structures, in chronological order of: Yanayacu Flexure, Jachauangu Fold and normal faults deformation events.