Soatá Formation
The Soatá Formation is a geological formation of the northern Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The formation consists mainly of shales with conglomerates and dates to the Quaternary period; Late Pleistocene epoch. The heavily eroded formation has a maximum measured thickness of. It contains the lacustrine and fluvio-glacial sediments of elongated paleolake Soatá, that existed on the Altiplano in the valley of the Chicamocha River.
Fossils of the gomphothere Haplomastodon waringi, the capibara Neochoerus sp. and the deer species Odocoileus cf. salinae have been found in the Soatá Formation.
Knowledge about the formation has been provided by Colombian geologists Carlos Villarroel, Jorge Brieva and others.
Etymology
The formation was first proposed and named after Soatá by Villarroel et al. in 2001. The type locality is defined near Portugalete, Soatá.Regional setting
The Altiplano Cundiboyacense, in the Eastern Ranges of the Colombian Andes, was formed late in the regional uplift of the Andean orogeny. It is estimated that the main stage of uplift happened during the Plio-Pleistocene. The Western and Central Ranges were submerged much earlier, leaving a corridor to the Caribbean in the Neogene.The compression in the Andean orogenic belt caused the formation of fold and thrust belts in the Eastern Ranges, where Cretaceous and Jurassic normal faults were inverted as thrust faults lifting up the Paleozoic, Mesozoic and Paleogene strata. A hiatus existed on the Altiplano between the Late Eocene and Late Miocene, in several parts of the Altiplano continuing until the Pleistocene.
During the glacials and interglacials of the Pleistocene, several paleolakes formed on the Altiplano Cundiboyacense, of which Lake Humboldt on the Bogotá savanna was the most extensive. Rivers were restricted during the drier glacial periods and the vegetation changed from páramo to Andean forest between the glacials and stadials and interglacials and interstadials.
Description
Lithologies
The Soatá Formation consists of whitish calcareous claystones and sandy siltstones with plagioclase, hematite, zircon, green and reddish biotite, hornblende and crystalline calcite in its upper, older terrace. This unit also contains foraminifera and fragments of shells.The middle, younger unit is composed of basal greyish claystones with non-uniform matrix-supported conglomerates at the upper section. The uppermost layer contains siltstones, probably of volcaniclastic origin.
The youngest sediments are found deepest in the basin and consist of claystones and greenish matrix-supported conglomerates. Rootlets and mammal fossils are more abundant in this layer.