Simijaca Formation

Simijaca Formation
Stratigraphic range: Cenomanian-Turonian ~100–90 Ma PreꞒ Ꞓ O S D C P T J K Pg N
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).

Etymology

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.^[1]^[2]

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]

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Type locality of the Simijaca Formation on the Altiplano Cundiboyacense

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]

Acosta Garay, Jorge, and Carlos E. Ulloa Melo. 2001. Geología de la Plancha 208 Villeta - 1:100,000, 1-84. INGEOMINAS. Accessed 2017-03-23.
García González, Mario; Ricardo Mier Umaña; Luis Enrique Cruz Guevara, and Mauricio Vásquez. 2009. Informe Ejecutivo - evaluación del potencial hidrocarburífero de las cuencas colombianas, 1-219. Universidad Industrial de Santander.
Montoya Arenas, Diana María, and Germán Alfonso Reyes Torres. 2005. Geología de la Sabana de Bogotá, 1–104. INGEOMINAS.
Villamil, Tomas. 2012. Chronology Relative Sea Level History and a New Sequence Stratigraphic Model for Basinal Cretaceous Facies of Colombia, 161–216. Society for Sedimentary Geology (SEPM).

Ulloa, Carlos E, and Erasmo Rodríguez. 2009. Plancha 170 - Vélez - 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
Fuquen M., Jaime A, and José F. Osorno M. 2009. Plancha 190 - Chiquinquirá - 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
Ulloa, Carlos, and Jorge Acosta. 1998. Plancha 208 - Villeta - 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
Montoya, Diana María, and Germán Reyes. 2009. Plancha 209 - Zipaquirá - 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
Ulloa, Carlos E; Erasmo Rodríguez, and Jorge E. Acosta. 1998. Plancha 227 - La Mesa - 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.
Acosta, Jorge E., and Carlos E. Ulloa. 1998. Plancha 246 - Fusagasugá - 1:100,000, 1. INGEOMINAS. Accessed 2017-06-06.

Gómez, J.; N.E. Montes; Á. Nivia, and H. Diederix. 2015. Plancha 5-09 del Atlas Geológico de Colombia 2015 – escala 1:500,000, 1. Servicio Geológico Colombiano. Accessed 2017-03-23.