The Tunjuelo Formation, Río Tunjuelo or Río Tunjuelito Formation (, Q1tu, Qpt, Qcc) is a geological formation of the Bogotá savanna, Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The formation consists mainly of conglomerates with intercalating shales and sandstones. The Tunjuelo Formation dates to the Quaternary period; covering the complete Pleistocene epoch, and has a maximum thickness of . It is a formation of the lacustrine and fluvio-glacial sediments of Lake Humboldt.
Etymology The formation was first defined and named by Helmens and Van der Hammen in 1995 after the Tunjuelo River, also called Tunjuelito River, of southern Bogotá.Montoya & Reyes, 2005, p.71
Description Lithologies The Tunjuelo Formation consists mainly of conglomerates with intercalating shales and sandstones.
Stratigraphy and depositional environment The Tunjuelo Formation conformably overlies the Marichuela Formation and in other parts the Subachoque Formation. The Tunjuelo Formation is overlain by the thin Chía Formation. The age has been estimated to be Pleistocene based on palynology and radiocarbon dating, covering the Pleistocene from 2.6 to 0.01 Ma.Montoya & Reyes, 2005, p.72 The depositional environment has been interpreted as fluvio-glacial terraces.
Outcrops
The Tunjuelo Formation is found at its type locality in the Tunjuelo River valley, in the synclinal of Guasca, near Cogua, Cundinamarca, and in the basins of the rivers San Cristóbal, San Francisco, Arzobispo and Subachoque, and the creeks (quebradas) Las Delicias, La Vieja, Rosales and Chicó of the Colombian capital.Lobo Guerrero, 1992, p.6 In the Tunjuelo River valley, the formation is crossed by the northeast–southwest oriented Yerbabuena Fault.Geological Map Bogotá, 1997
See also
Geology of the Eastern Hills Geology of the Ocetá Páramo Geology of the Altiplano Cundiboyacense
References
Bibliography
Maps
External links