Jama Formation
| Jama Formation | |
|---|---|
| Stratigraphic range: Pliocene-Early Pleistocene (Montehermosan-Ensenadan) ~ | |
| Type | Geological formation |
| Lithology | |
| Primary | Claystone, sandstone |
| Location | |
| Coordinates | 0°12′S 80°18′W / 0.2°S 80.3°W |
| Approximate paleocoordinates | 0°18′S 79°54′W / 0.3°S 79.9°W |
| Region | Manabí Province |
| Country |  Ecuador |
| Type section | |
| Named for | Jama |
  Jama Formation (Ecuador) | |
The Jama Formation is a Pliocene to Early Pleistocene (Montehermosan to Ensenadan in the SALMA classification) geological formation in Ecuador. The claystones and sandstones were deposited in a coastal environment. The age of the Jama Formation is constrained by 40Ar/39Ar dating of tephra beds.[1] The formation is correlated to the Charco Azul Formation of western Panama and southeastern Costa Rica.[2]
Subdivision
[edit]The formation is subdivided in, from top to base:
- El Matal Member (60 metres (200 ft), fluvial)
- Punta Ballena Member (lower shoreface)
- Punta Pasa Borracho Member (20 metres (66 ft), marine)
Fossil content
[edit]The formation has provided bivalve, gastropod and scaphopod fossils.
See also
[edit]
References
[edit]- ^ Jama Formation at Fossilworks.org
- ^ Charco Azul Formation at Fossilworks.org
Further reading
[edit]- G. Cantalamessa, C. Di Celma, and L. Ragaini. 2005. Sequence stratigraphy of the Punta Ballena Member of the Jama Formation (Early Pleistocene, Ecuador): insights from integrated sedimentologic, taphonomic and paleoecologic analysis of molluscan shell concentrations. Palaeogeography, Palaeoclimatology, Palaeoecology 216:1-25
- H. A. Pilsbry and A.A. Olsson. 1941. A Pliocene fauna from Western Ecuador. Proceedings of the Natural Sciences of Philadelphia 93:1-79