Una sub-cuenca de antearco pre-acrecionaria del cretácico tardío: sub-cuenca río playas, sur del Ecuador

Abstract:

The Rio Playas sub-basin represents the upper part of the sedimentary infilling of the Cretaceous Alamor Lancones basin of southern Ecuador. The basement of the Alamor-Lancones basin is formed by volcanic rocks of the Celica and Alamor formations to the east and metamorphic rocks of the Amotape-Tahuín Massif to the west of the basin. Sedimentological and provenance analyzes in the Rio Playas sub-basin help to elucidate the late Cretaceous to Tertiary story of this forearc basin and neighboring regions. The analysis of heavy minerals and the geochemistry of pyroxenes for the volcano-sedimentary sequence of the Albian-Turonian Alamor Formation indicates that the basement of the east of the Alamor-Lancones basin is formed by a volcanism of tholeiitic composition, related to the Celica arc of the Cretaceous. Sedimentological analysis of the Late Cretaceous El Naranjo and Casanga formations suggests that these formations were deposited in a submarine fan environment. U-Pb in detrital zircons dating, heavy mineral and QFL data, from the Casanga and El Naranjo formations show that they were derived from a volcanic arc coeval volcanism during the deposition. The Río Playas Formation of Paleocene-Eocene age is interpreted as deposited in a continental environment. Heavy mineral and QFL show a significant domain of metamorphic minerals in this formation, suggesting that an important tectonic event occurred prior to the deposition of the overlying the Río Playas Formation. This information is confirmed by U-Pb dating for this formation, which indicates that the sediments were derived mainly from an emerging Eastern Cordillera, probably due to the collision of the Caribbean Plateau to the South American continental margin between 73-70 Ma.

Año de publicación:

2017

Keywords:

• GEOLOGIA
• Sedimentología

Fuente:

rraae