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Group of geologic formations in Peru From Wikipedia, the free encyclopedia
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 |
Region | Casma Province, Ancash Region |
Country | ![]() |
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]
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