Pacho Formation
{{short description|Geological formation in the Colombian Andes}}
{{Infobox rockunit
| name = Pacho Formation
| period = Cenomanian
| age = Late Albian-Cenomanian
~{{fossil range|102|97}}
| image =
| imagesize =
| caption =
| type = Geological formation
| prilithology = Siltstone
| otherlithology = Shale
| unitof = Villeta Group
| subunits =
| underlies = Simijaca Formation
| overlies = Hiló Formation
| thickness = ~{{convert|1050|m|ft|abbr=on}}
| area =
| map = Blakey 105Ma - COL.jpg
| map_caption = Paleogeography of Northern South America
105 Ma, {{small|by Ron Blakey}}
| location =
| coordinates = {{coord|4|27|07|N|74|03|20|W|display=inline,title}}
| region = Altiplano Cundiboyacense
Eastern Ranges, Andes
| country = Colombia
| extent =
| namedfor = Pacho
| namedby = Ulloa
| year_ts = 1982
| location_ts = Pacho
| coordinates_ts = {{coord|4|27|07|N|74|03|20|W|display=inline}}
| paleocoordinates_ts =
| region_ts = Cundinamarca
| country_ts = Colombia
| thickness_ts =
}}
The Pacho Formation ({{langx|es|Limolitas de Pacho}}, Kslp) is a geological formation of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The formation consisting of alternating siltstones and shales with siderite concretions dates to the Middle Cretaceous period; Late Albian to Cenomanian epochs and has an approximate thickness of {{convert|1050|m|ft}}.
Etymology
The formation was defined and named in 1982 by Ulloa after Pacho, Cundinamarca.
Description
= Lithologies =
The Pacho Formation has an approximate thickness of {{convert|1050|m|ft}}, and is characterised by a sequence of alternating siltstones and shales with siderite concretions.Acosta & Ulloa, 2002, p.45
= Stratigraphy and depositional environment =
The Pacho Formation, pertaining to the Villeta Group, partly overlies and is partly lateral equivalent with the Hiló Formation and is partly overlain by and partly time equivalent with the Simijaca Formation. The age has been estimated to be Late Albian to Cenomanian. Stratigraphically, the formation is time equivalent with the Une Formation. The formation has been deposited in an outer marine platform environment.
Outcrops
{{Location map | Bogotá savanna
| width = 250
| lat_deg = 5.253664
| lon_deg = -74.341091
| label =
| float = left
| position = right
| mark = Green pog.svg
| marksize = 12
| caption = Type locality of the Pacho Formation to the northwest of the Bogotá savanna
}}
The Pacho Formation is found around its type locality near Pacho.
{{clear left}}
See also
{{Portal|Colombia|Geology}}
:{{icon|FAC}} Geology of the Eastern Hills
:{{icon|B}} Geology of the Ocetá Páramo
:{{icon|C}} Geology of the Altiplano Cundiboyacense
{{clear}}
References
{{reflist|30em}}
= Bibliography =
- {{citation |last1=Acosta Garay |first1=Jorge E. |last2=Ulloa Melo |first2=Carlos E. |year=2002 |title=Mapa Geológico del Departamento de Cundinamarca - 1:250,000 - Memoria explicativa |url=http://nebula.wsimg.com/ca3411dab87400d504f8461f0256772a?AccessKeyId=75F883B260454DDA3D4B&disposition=0&alloworigin=1 |publisher=INGEOMINAS |pages=1–108 |accessdate=2017-04-26}}
- {{citation |last=Villamil |first=Tomas |year=2012 |title=Chronology Relative Sea Level History and a New Sequence Stratigraphic Model for Basinal Cretaceous Facies of Colombia |publisher=Society for Sedimentary Geology (SEPM) |pages=161–216}}
== Maps ==
- {{citation |last1=Ulloa |first1=Carlos |last2=Acosta |first2=Jorge |year=1998 |title=Plancha 208 - Villeta - 1:100,000 |url=https://drive.google.com/open?id=0BwFQPMJEi17QMjhLeWJ0aU1Za1U |publisher=INGEOMINAS |pages=1 |accessdate=2017-06-06}}
- {{citation |last1=Ulloa |first1=Carlos E |last2=Rodríguez |first2=Erasmo |last3=Acosta |first3=Jorge E. |year=1998 |title=Plancha 227 - La Mesa - 1:100,000 |url=https://drive.google.com/open?id=0BwFQPMJEi17QR0k3cWk2aTlwbEk |publisher=INGEOMINAS |pages=1 |accessdate=2017-06-06}}
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 |pages=1 |accessdate=2017-03-16}}
Category:Geologic formations of Colombia
Category:Lower Cretaceous Series of South America
Category:Upper Cretaceous Series of South America