Pacho Formation

Last updated
Pacho Formation
Stratigraphic range: Late Albian-Cenomanian
~102–97  Ma
O
S
D
C
P
T
J
K
Pg
N
Type Geological formation
Unit of Villeta Group
Underlies Simijaca Formation
Overlies Hiló Formation
Thickness~1,050 m (3,440 ft)
Lithology
Primary Siltstone
Other Shale
Location
Coordinates 4°27′07″N74°03′20″W / 4.45194°N 74.05556°W / 4.45194; -74.05556
Region Altiplano Cundiboyacense
Eastern Ranges, Andes
CountryFlag of Colombia.svg  Colombia
Type section
Named for Pacho
Named byUlloa
Location Pacho
Year defined1982
Coordinates 4°27′07″N74°03′20″W / 4.45194°N 74.05556°W / 4.45194; -74.05556
Region Cundinamarca
CountryFlag of Colombia.svg  Colombia
Blakey 105Ma - COL.jpg
Paleogeography of Northern South America
105 Ma, by Ron Blakey

The Pacho Formation (Spanish : 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 1,050 metres (3,440 ft).

Contents

Etymology

The formation was defined and named in 1982 by Ulloa after Pacho, Cundinamarca. [1]

Description

Lithologies

The Pacho Formation has an approximate thickness of 1,050 metres (3,440 ft), and is characterised by a sequence of alternating siltstones and shales with siderite concretions. [1]

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. [1]

Outcrops

Sabana de Bogota.png
Green pog.svg
Type locality of the Pacho Formation to the northwest of the Bogotá savanna

The Pacho Formation is found around its type locality near Pacho. [1]

Regional correlations

Cretaceous stratigraphy of the central Colombian Eastern Ranges
AgePaleomap VMM Guaduas-Vélez W Emerald Belt Villeta anticlinal Chiquinquirá-
Arcabuco
Tunja-
Duitama
Altiplano Cundiboyacense El Cocuy
Maastrichtian Blakey 065Ma - COL.jpg Umir Córdoba Seca eroded Guaduas Colón-Mito Juan
Umir Guadalupe
Campanian Córdoba
Oliní
Santonian La Luna Cimarrona - La Tabla La Luna
Coniacian Oliní Villeta Conejo Chipaque
Güagüaquí Loma Gorda undefined La Frontera
Turonian Blakey 090Ma - COL.jpg Hondita La Frontera Otanche
Cenomanian Simití hiatus La Corona Simijaca Capacho
Pacho Fm. Hiló - Pacho Churuvita Une Aguardiente
Albian Blakey 105Ma - COL.jpg Hiló Chiquinquirá Tibasosa Une
Tablazo Tablazo Capotes - La Palma - Simití Simití Tibú-Mercedes
Aptian Capotes Socotá - El Peñón Paja Fómeque
Paja Paja El Peñón Trincheras Río Negro
La Naveta
Barremian Blakey 120Ma - COL.jpg
Hauterivian Muzo Cáqueza Las Juntas
Rosablanca Ritoque
Valanginian Ritoque Furatena Útica - Murca Rosablanca hiatus Macanal
Rosablanca
Berriasian Blakey 150Ma - COL.jpg Cumbre Cumbre Los Medios Guavio
Tambor Arcabuco Cumbre
Sources

See also

Cscr-candidate.svg Geology of the Eastern Hills
Symbol b class.svg Geology of the Ocetá Páramo
Symbol c class.svg Geology of the Altiplano Cundiboyacense

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<span class="mw-page-title-main">Oliní Group</span> Fossiliferous geological group

The Oliní Group (Spanish: Grupo Oliní, K3k5o, K2ol, Kso) is a fossiliferous geological group of the VMM, VSM and the eastern flanks of the Central and western flanks of the Eastern Ranges of the Colombian Andes. The regional group stretches from north to south across approximately 700 kilometres (430 mi) and dates to the Late Cretaceous period; Coniacian, Santonian and Campanian epochs, and has a maximum thickness of 287 metres (942 ft). Fossils of Eonatator coellensis have been found in the unit, near Coello, Tolima.

References

  1. 1 2 3 4 Acosta & Ulloa, 2002, p.45

Bibliography

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