The Loma Gorda Formation (, Kl, Kslg) is a

fossiliferous A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved i ...

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...

of the Upper Magdalena Valley (VSM) and surrounding Central and

Eastern Ranges The Eastern Ranges is an Australian rules football team that currently competes in the Talent League, the Victorian statewide under-18s competition. History Inaugural playing squad (1992) Honours *Premiers (2): 2002, 2013 *Runners-up (6): 199 ...

of the

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

, 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

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility. Although its permeabil ...

s and

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...

s, dates to the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

period;

Turonian The Turonian is, in the International Commission on Stratigraphy, ICS' geologic timescale, the second age (geology), age in the Late Cretaceous epoch (geology), Epoch, or a stage (stratigraphy), stage in the Upper Cretaceous series (stratigraphy), ...

Coniacian The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by ...

epochs, and has a maximum thickness of .

Etymology

The formation was named in 1966 by De Porta, named Loma Gorda ("Fat Hill") in Ricaurte, Cundinamarca.Acosta & Ulloa, 2002, p.23

Description

Lithologies

The Loma Gorda Formation is characterised by laminated

s and

s with

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime (mineral), lime or being chalky. The term is used in a wide variety of Science, scientific disciplines. In zoology ''Calcare ...

concretions.Acosta & Ulloa, 2002, p.24 The formation has provided fossils of '' Ankinatsytes venezolanus'', '' Barroisiceras onilahyense'', '' Codazziceras ospinae'', '' Eulophoceras jacobi'', ''

Fagesia catinus ''Fagesia'' is a small, subglobular ammonite (suborder Ammonitina) belonging to the vascoceratid family of the Acanthocerataceae that lived during the Turonian stage of the Late Cretaceous, 92–88 Ma ago. The shell of ''Fagesia'' is about 9. ...

'', '' 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.''.Patarroyo, 2011

Stratigraphy and depositional environment

The Loma Gorda Formation is the uppermost unit of the Güagüaquí Group. It overlies the

Hondita Formation The Hondita Formation (, Ksh) 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 To ...

and is overlain by the Oliní Group. The age has been estimated on the basis of ammonites to be ranging from

. Stratigraphically, the formation is time equivalent with the upper parts of the

Chipaque Chipaque is a municipality and town in the Eastern Province of the department of Cundinamarca, Colombia. The municipality of is located at an altitude of in the Eastern Ranges of the Colombian Andes with its westernmost part situated in the E ...

, La Luna and

La Frontera Formation The La Frontera Formation (, K2F, Ksf) is a geological formation, part of the Villeta Group, of the Altiplano Cundiboyacense and neighbouring areas of the Eastern Ranges of the Colombian Andes. The sequence of limestones and lydites dates to the ...

s.Acosta & Ulloa, 2002, p.22 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 The mineral pyrite ( ), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Fe S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic luster and pale brass-yellow hue ...

rim.Villamil, 2012, p.173

Outcrops

The type locality of the Loma Gorda Formation is located close to Loma Gorda in Ricaurte, Cundinamarca.Acosta & Ulloa, 2001, p.43 Other

outcrop An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth and other terrestrial planets. Features Outcrops do not cover the majority of the Earth's land surface because in most p ...

s of the Loma Gorda Formation have been noted east of the

Magdalena River The Magdalena River (, ; less commonly ) is the main river of Colombia, flowing northward about through the western half of the country. It takes its name from the biblical figure Mary Magdalene. It is navigable through much of its lower reaches, ...

northeast of

Honda commonly known as just Honda, is a Japanese multinational corporation, multinational Conglomerate (company), conglomerate automotive manufacturer headquartered in Minato, Tokyo, Japan. Founded in October 1946 by Soichiro Honda, Honda has bee ...

,Plancha 207, 2010 west of Nariño,Plancha 245, 1999 west across the Magdalena River in San Luis, Tolima,Plancha 264, 2002 between the Tetuán and

Saldaña River The Saldaña River is a river of Colombia. It drains into the Caribbean Sea via the Magdalena River. See also *List of rivers of Colombia Atlantic Ocean Amazon River Basin * Amazon River ** Guainía River or Negro River *** Vaupés River ...

s west of Coyaima and east and west of

Ataco Ataco is a town and municipality located in the Tolima Department, Tolima department of Colombia. The population of the municipality was 13,470 in the 2018 census. The Colombian state has been accused of human rights violations in Ata Climate ...

,Plancha 282, 1993 to the east of the Prado River reservoir,Plancha 283, 2009 north and west of

Aipe Aipe is a town and municipality in the Huila Department, Colombia. It is located on the west bank of the Magdalena River in the Central Ranges of the Colombian Andes at altitudes between . Aipe borders Natagaima, Ataco and Planadas of the depar ...

,Plancha 302, 1993 surrounding

Alpujarra The Alpujarra (, ) is a natural and historical region in Andalusia, Spain, on the south slopes of the Sierra Nevada and the adjacent valley. The average elevation is above sea level. It extends over two provinces, Granada and Almería; i ...

, Tolima,Plancha 303, 2002 south of

Palermo Palermo ( ; ; , locally also or ) is a city in southern Italy, the capital (political), capital of both the autonomous area, autonomous region of Sicily and the Metropolitan City of Palermo, the city's surrounding metropolitan province. The ...

, Huila, displaced by the

Baché Fault A share taxi, shared taxi, taxibus, or jitney or dollar van in the US, or marshrutka in former Soviet countries, is a mode of transport which falls between a taxicab and a bus. Share taxis are a form of paratransit. They are vehicles for hire and ...

,Plancha 323, 1998 east of Iquira,Plancha 344, 1999 north of

Yaguará Yaguará () is a town and municipality in the Huila Department, Colombia. The urban centre is located at an elevation of in the Magdalena River, Magdalena River Valley and the Cordillera Oriental (Colombia), Eastern Ranges of the Colombian Andes. ...

,Plancha 345, 1999 south of

La Plata La Plata () is the capital city of Buenos Aires province, Argentina. According to the 2022 Argentina census, census, the La Plata Partido, Partido has a population of 772,618 and its metropolitan area, the Greater La Plata, has 938,287 inhabit ...

where the formation is cut by the Itaibe Fault,Plancha 366, 1998 a small patch east of Gigante, Huila,Plancha 367, 2003 northwest and northeast of San Agustín,Plancha 388, 2002 and north of Timaná surrounding the

.Plancha 389, 2003

Regional correlations

Notes

References

Bibliography

* * *

Maps

* * * * * * * * * * * * * * * *

External links

* {{citation , last1=Gómez , first1=J. , last2=Montes , first2=N.E. , last3=Nivia , first3=Á. , last4=Diederix , first4=H. , year=2015 , title=Plancha 5-09 del Atlas Geológico de Colombia 2015 – escala 1:500,000 , url=https://www.researchgate.net/publication/309533589 , publisher=

Servicio Geológico Colombiano The Colombian Geological Survey (CGS) (; formerly known as INGEOMINAS) is a scientific Government agency, agency of the Colombian government in charge of contributing to the socioeconomic development of the nation through research in basic and ap ...

, pages=1 , accessdate=2017-03-16 Geologic formations of Colombia Cretaceous Colombia Upper Cretaceous Series of South America Turonian Stage Coniacian Stage Shale formations Siltstone formations Open marine deposits Fossiliferous stratigraphic units of South America Paleontology in Colombia Formations Formations Formations Magdalena River