Barzalosa Formation | |
---|---|
Stratigraphic range: ~Mid Eocene-Oligocene orOligocene-Early Miocene ~40–20 Ma
| |
Type | Geological formation |
Underlies | Honda Gp., Carmen de Apicalá Conglomerate |
Overlies | La Tabla Fm., Olini Gp., Seca Fm. |
Thickness | ~360 m (1,180 ft) |
Lithology | |
Primary | Conglomerates |
Other | Sandstones, siltstones, shale, gypsum |
Location | |
Coordinates | 4°21′50.2″N 74°47′29.8″W / 4.363944°N 74.791611°W / 4.363944; -74.791611 |
Approximate paleocoordinates | 2°42′N 71°12′W / 2.7°N 71.2°W / 2.7; -71.2 |
Region | Upper Magdalena Valley Central & Eastern Ranges Andes |
Country | ![]() |
Type section | |
Named for | Barzalosa |
Named by | Scheibe |
Location | Girardot |
Year defined | 1934 |
Coordinates | 4°21′50.2″N 74°47′29.8″W / 4.363944°N 74.791611°W / 4.363944; -74.791611 |
Region | Cundinamarca |
Country | ![]() |
![]() Paleogeography of Northern South America 35 Ma, by Ron Blakey |
The Barzalosa Formation (Spanish: Formación Barzalosa, Pgb, Pgba) is a fossiliferous geological formation of the Upper Magdalena Valley and the bounding foothills of the Central Ranges and Eastern Ranges of the Colombian Andes. The formation consists of conglomerates, sandstones and siltstones. The Barzalosa Formation probably dates to the Late PaleogenetoEarly Neogene period; OligocenetoEarly Miocene epochs, and has an approximate thickness of 360 metres (1,180 ft). Fossils of Balanerodus logimus, Lophiodolodus chaparralensis, Xenastrapotherium chaparralensis, Protheosodon sp. and Proadinotherium sp. have been uncovered from the formation in Chaparral, Tolima.
The formation was defined by Scheibe in 1934 and named after Barzalosa, a veredaofGirardot, Cundinamarca. Cáceres and Etayo elevated the "Pisos de Barzalosa" to a formation in 1969.[1]
The Barzalosa Formation consists of conglomerates, sandstones and siltstones.[2] In parts, the formation contains shale beds and gypsum.[3]
The approximately 360 metres (1,180 ft) thick Barzalosa Formation overlies the Olini Group and the Seca Formation in the west and is overlain by the Honda Group.[2] In the east towards Fusagasugá, the formation overlies the La Tabla Formation and is overlain by the Carmen de Apicalá Conglomerate.[4] As the formation does not contain foraminifera, the age is difficult to establish, but has been estimated to be OligocenetoEarly Miocene,[2]orMiddle Eocene to Oligocene.[5] The depositional environment has been interpreted as alluvial fans and braided rivers.[6]
Location | Department | Fossils | Notes |
---|---|---|---|
Alto San José, Chaparral | Tolima | Balanerodus logimus | |
Lophiodolodus chaparralensis | |||
Xenastrapotherium chaparralensis | |||
Protheosodon sp. | |||
Proadinotherium sp. | |||
Megalonychoidae indet., Gavialidae indet. |
The Barzalosa Formation is apart from its type locality found in Tocaima and to the east of Agua de Dios,[1] and on the western side of the Magdalena River around Chaparral, Tolima.[12]