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
TypeGeological group
Lithology
PrimaryLimestone, marl, sandstone, conglomerate
OtherGypsum, tuff
Location
Coordinates10°54′S 76°48′W / 10.9°S 76.8°W / -10.9; -76.8
RegionCasma Province, Ancash Region
Country Peru
ExtentWest Peruvian Basin
Type section
Named forCasma
Casma Group is located in Peru
Casma Group
Casma Group (Peru)

Description

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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

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  1. ^ a b Compare et al, 1983
  2. ^ a b c Pfiffner & González, 2013

Bibliography

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  • 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", Geosciences, 3 (2): 262–310, Bibcode:2013Geosc...3..262P, doi:10.3390/geosciences3020262, retrieved 2019-02-21