- Source: Loma Gorda Formation
The Loma Gorda Formation (Spanish: Formación Loma Gorda, Kl, Kslg) is a fossiliferous geological formation of the Upper Magdalena Valley (VSM) and surrounding Central and Eastern Ranges of the Colombian Andes, extending from Cundinamarca in the north to Huila and easternmost Tolima in the south. The uppermost unit of the Güagüaquí Group, a sequence of laminated siltstones and shales, dates to the Late Cretaceous period; Turonian to Coniacian epochs, and has a maximum thickness of 167 metres (548 ft).
Etymology
The formation was named in 1966 by De Porta, named Loma Gorda ("Fat Hill") in Ricaurte, Cundinamarca.
Description
= Lithologies
=The Loma Gorda Formation is characterised by laminated siltstones and shales with calcareous concretions. The formation has provided fossils of Ankinatsytes venezolanus, Barroisiceras onilahyense, Codazziceras ospinae, Eulophoceras jacobi, Fagesia catinus, Hauericeras madagascarensis, Hoplitoides ingens, H. lagiraldae, Mitonia gracilis, Mytiloides kossmati, M. goppelnensis, M. scupini, Neoptychites cf. andinus, Paralenticeras sieversi, Paramammites sp., Peroniceras subtricarinatum, Prionocycloceras guayabanum, Reesidites subtuberculatum, Subprionotropis colombianus, Allocrioceras sp., Anagaudryceras sp., Anomia sp., Benueites sp., Choffaticeras sp., Dydimotis sp., Forresteria sp., Gauthiericeras sp., Morrowites sp., Nannovascoceras sp., and Quitmaniceras sp..
= Stratigraphy and depositional environment
=The Loma Gorda Formation is the uppermost unit of the Güagüaquí Group. It overlies the Hondita Formation and is overlain by the Oliní Group. The age has been estimated on the basis of ammonites to be ranging from Turonian to Coniacian. Stratigraphically, the formation is time equivalent with the upper parts of the Chipaque, La Luna and La Frontera Formations. The formation was deposited in a relative highstand sequence with an oceanic oxygen depletion event, sharply marked in Colombia and characterised by the appearance of calcareous concretions with a thick pyrite rim.
Outcrops
The type locality of the Loma Gorda Formation is located close to Loma Gorda in Ricaurte, Cundinamarca. Other outcrops of the Loma Gorda Formation have been noted east of the Magdalena River northeast of Honda, west of Nariño, west across the Magdalena River in San Luis, Tolima, between the Tetuán and Saldaña Rivers west of Coyaima and east and west of Ataco, to the east of the Prado River reservoir, north and west of Aipe, surrounding Alpujarra, Tolima, south of Palermo, Huila, displaced by the Baché Fault, east of Iquira, north of Yaguará, south of La Plata where the formation is cut by the Itaibe Fault, a small patch east of Gigante, Huila, northwest and northeast of San Agustín, and north of Timaná surrounding the Magdalena River.
Regional correlations
Legend
group
important formation
fossiliferous formation
minor formation
(age in Ma)
proximal Llanos (Medina)
distal Llanos (Saltarin 1A well)
See also
Geology of the Eastern Hills
Geology of the Ocetá Páramo
Geology of the Altiplano Cundiboyacense
Geology of the Middle Magdalena Valley
Notes
References
= Bibliography
=Acosta, Jorge E.; Ulloa, Carlos E. (2002), Mapa geológico del Departamento de Cundinamarca 1:250,000 - Memoria Explicativa, INGEOMINAS, pp. 1–108
Patarroyo, Pedro (2011), "Sucesión de Amonitas del Cretácico Superior (Cenomaniano-Coniaciano) de la parte más alta de la Formación Hondita y de la Formación Loma Gorda en la Quebrada Bambucá, Aipe - Huila (Colombia)" (PDF), Boletín de Geología, 33: 69–92, retrieved 2019-03-13
Villamil, Tomas (2012), Chronology Relative Sea Level History and a New Sequence Stratigraphic Model for Basinal Cretaceous Facies of Colombia, Society for Sedimentary Geology (SEPM), pp. 161–216
Maps
Barrero L., Darío; Vesga O, Carlos J. (2009), Plancha 188 - La Dorada - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
Barrero, Darío; Vesga, Carlos J. (2010), Plancha 207 - Honda - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
Acosta, Jorge E.; Guatame, Rafael; Torres, Oscar; Solano, Frank (1999), Plancha 245 - Girardot - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
Calcedo, Juan Carlos; Terraza, Roberto (2000), Plancha 264 - Espinal - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
Carvajal, Cesar; Fuquen, Jaime; Gómez, Luis (1993), Plancha 282 - Chaparral - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
Cossio, Ubaldo; Rodríguez, Gabriel; Rodríguez, Miguel (1995), Plancha 283 - Purificación - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
Fuquen, Jaime; Rodríguez, Gabriel; Cossio, Ubaldo; Núñez, Alberto (1993), Plancha 302 - Aipe - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
Acosta, Jorge; Caro, Pablo; Fuquen, Jaime; Osorno, José (2002), Plancha 303 - Colombia - 1:100,000, INGEOMINAS, p. 1
Ferreira, Paulina; Núñez, Alberto; Rodríguez, Miguel (1998), Plancha 323 - Neiva - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
Marquínez, Germán; Morales, C.; Núñez, Alberto (1999), Plancha 344 - Tesalia - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
Velandia, F.; Morales, C.J.; Caicedo, J.C.; Núñez, Alberto (1999), Plancha 345 - Campoalegre - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
Marquínez, Germán; Rodríguez, Yohana; Terraza, Roberto; Martínez, Mario (2003), Plancha 365 - Coconuco - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
Rodríguez, Gabriel; Ferreira, Paulina; Velandia, Francisco; Núñez, Alberto (1998), Plancha 366 - Garzón - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
Rodríguez, Gabriel; Zapata, Gilberto; Velázquez, M. (2003), Plancha 367 - Gigante - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
Cárdenas, Jorge; Fuquen, Jaime; Núñez, Alberto (2002), Plancha 388 - Pitalito - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
Rodríguez, Gabriel; Zapata, Gilberto; Velázquez, M. (2003), Plancha 389 - Timaná - 1:100,000, INGEOMINAS, p. 1, retrieved 2017-06-06
External links
Gómez, J.; Montes, N.E.; Nivia, Á.; Diederix, H. (2015), Plancha 5-09 del Atlas Geológico de Colombia 2015 – escala 1:500,000, Servicio Geológico Colombiano, p. 1, retrieved 2017-03-16