Simijaca Formation

Simijaca Formation
Stratigraphic range: Cenomanian-Turonian ~
Type	Geological formation
Unit of	Villeta Group
Underlies	La Frontera Formation
Overlies	Chiquinquirá Sst., Churuvita Fm., Hiló Fm., Pacho Fm.
Thickness	up to 693 m (2,270 ft)
Lithology
Primary	Mudstone
Other	Shale, sandstone, limestone
Location
Coordinates	5°29′15″N 73°50′55″W / 5.48750°N 73.84861°W / 5.48750; -73.84861
Region	Altiplano Cundiboyacense Eastern Ranges, Andes
Country	Colombia
Type section
Named for	Simijaca
Named by	Ulloa & Rodríguez
Location	South of Simijaca
Year defined	1991
Coordinates	5°29′15″N 73°50′55″W / 5.48750°N 73.84861°W / 5.48750; -73.84861
Region	Cundinamarca, Boyacá
Country	Colombia
Thickness at type section	432 metres (1,420 ft)
Paleogeography of Northern South America 90 Ma, by Ron Blakey

The Simijaca Formation (Spanish: Formación Simijaca, K₂S, Kss) is a geological formation of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The predominantly mudstone formation dates to the Late Cretaceous period; Turonian and Cenomanian epochs, and has a maximum thickness of 693 metres (2,274 ft).

The formation was defined and named in 1991 by Ulloa and Rodríguez after Simijaca, Cundinamarca.¹

The Simijaca Formation is characterised by a sequence of mudstones, grey and black shales with sandstone and limestone intercalations.¹²

The Simijaca Formation conformably overlies the Chiquinquirá Sandstone, and the Hiló and Pacho Formations, and is overlain by the La Frontera Formation.³ The age has been estimated to be Turonian,¹ or Cenomanian.⁴ Stratigraphically, the formation is time equivalent with the Chipaque Formation.⁵ The formation has been deposited in an open marine platform setting.⁶ The deposition is represented by a maximum flooding surface.⁷

The Simijaca Formation is apart from its type locality in the Quebrada Don Lope,² found at surface in the north of the Bogotá savanna, in the Tabio anticlinal, along the road Ubaté-Carmen de Carupa,⁸ at the western and eastern flanks of the Aponsentos-Chiquinquirá Synclinal,⁹ near Tena, south of Anolaima and Cachipay,¹⁰ and between Anapoima and Granada.¹¹