Pacho Formation Explained

Pacho Formation
Period:Cenomanian
Age:Late Albian-Cenomanian
~
Type:Geological formation
Prilithology:Siltstone
Otherlithology:Shale
Unitof:Villeta Group
Underlies:Simijaca Formation
Overlies:Hiló Formation
Thickness:~1050m (3,450feet)
Map:Blakey 105Ma - COL.jpg
Coordinates:4.4519°N -74.0556°W
Region:Altiplano Cundiboyacense
Eastern Ranges, Andes
Namedfor:Pacho
Namedby:Ulloa
Year Ts:1982
Location Ts:Pacho
Coordinates Ts:4.4519°N -74.0556°W
Region Ts:Cundinamarca

The Pacho Formation (Spanish; Castilian: 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 1050m (3,450feet).

Etymology

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

Description

Lithologies

The Pacho Formation has an approximate thickness of 1050m (3,450feet), 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

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

See also

Geology of the Eastern Hills

Geology of the Ocetá Páramo

Geology of the Altiplano Cundiboyacense

References

Bibliography

Maps

Notes and References

  1. Acosta & Ulloa, 2002, p.45