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 / -10.9; -76.8
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; 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.