Casma Group
| Casma Group | |
|---|---|
| Stratigraphic range: Albian-Cenomanian | |
| Type | Geological group |
| Lithology | |
| Primary | Limestone, marl, sandstone, conglomerate |
| Other | Gypsum, tuff |
| Location | |
| Coordinates | 10°54′S 76°48′W / 10.9°S 76.8°W |
| Region | Casma Province, Ancash Region |
| Country |  Peru |
| Extent | West Peruvian Basin |
| Type section | |
| Named for | Casma |
  Casma Group (Peru) | |
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.
Description
[edit]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]
References
[edit]Bibliography
[edit]- Compare, Dominique; Adline, Ghilaine; Romani, Maurice; Angeles, Carlos (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 (in Spanish), XII (1–2): 75–89, doi:10.3406/bifea.1983.1567, retrieved 2019-02-21
- Pfiffner, Adrian O.; Gonzalez, Laura (2013), "Mesozoic–Cenozoic Evolution of the Western Margin of South America: Case Study of the Peruvian Andes", Geoscience, 3 (2): 262–310, Bibcode:2013Geosc...3..262P, doi:10.3390/geosciences3020262, retrieved 2019-02-21
Major South American geological features | |||||
|---|---|---|---|---|---|
| Tectonic plates |  | ||||
| Cratons and shields | |||||
| Structures undergoing subduction | |||||
| Faults and shear zones | |||||
| Rifts and grabens |
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| Sedimentary basins |
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| Orogenies |
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| Metallogenetic provinces |
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| Volcanism |
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