Casma_Group
The Casma Group (Spanish: Grupo Casma) is a stratigraphic group of Cretaceous (Albian to Cenomanian) sedimentary formations exposed along the coast and within the Cordillera Occidental near Casma, Peru.
| Casma Group | |
|---|---|
| Stratigraphic range: Albian-Cenomanian | |
| Type | Geological group |
| Lithology | |
| Primary | Limestone, marl, sandstone, conglomerate |
| Other | Gypsum, tuff |
| Location | |
| Coordinates | 10.9°S 76.8°W / -10.9; -76.8 |
| Region | Casma Province, Ancash Region |
| Country |  Peru |
| Extent | West Peruvian Basin |
| Type section | |
| Named for | Casma |
The sediments of the Casma Group reflect deposition in two distinct environments of the West Peruvian Basin. Some sediments were deposited near the Casma Volcanic Arc in an intra-cratonic sedimentary basin that was occasionally connected to the ocean. Other sediments were deposited in what was once a continental platform bounded by reefs and with anoxic pockets.[1]
Together with the Morro Solar and Imperial Groups, the Casma Group contains clastic volcanosedimentary material derivative of the Mesozoic Casma Volcanic Arc.[2] The folding of the Casma Group sediments is the result of the Cretaceous Mochica Phase of the Andean orogeny.[2] The group is intruded by plutons of the Coastal Batholith of Peru.[2]
The Casma Group include the following lithologies: gypsum, limestone, marl, tuff, lava flows, sandstone and conglomerate.[1]
Bibliography
- Compare, Dominique; Ghilaine Adline; Maurice Romani, and Carlos Angeles. 1983. Contribución al estudio de las formaciones volcánicas y sedimentarias del Grupo Casma en la transversal del río Huara, Cuenca oeste-peruana. Bulletin de l'Institut français d'études andines XII(1–2). 75–89. Accessed 2019-02-21.
- Pfiffner, Adrian O., and Laura Gonzalez. 2013. Mesozoic–Cenozoic Evolution of the Western Margin of South America: Case Study of the Peruvian Andes. Geoscience 3(). 262–310. Accessed 2019-02-21.