Casma Group | |
---|---|
Stratigraphic range: Albian-Cenomanian | |
Type | Geological group |
Lithology | |
Primary | Limestone, marl, sandstone, conglomerate |
Other | Gypsum, tuff |
Location | |
Coordinates | 10°54′S76°48′W / 10.9°S 76.8°W |
Region | Casma Province, Ancash Region |
Country | Peru |
Extent | West Peruvian Basin |
Type section | |
Named for | Casma |
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.
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]
The geology of the Iberian Peninsula consists of the study of the rock formations on the Iberian Peninsula, connected to the rest of the European landmass by the Pyrenees. The peninsula contains rocks from every geological period from the Ediacaran to the Quaternary, and many types of rock are represented. World-class mineral deposits are also found there.
The Pyrenees are a 430-kilometre-long, roughly east–west striking, intracontinental mountain chain that divide France, Spain, and Andorra. The belt has an extended, polycyclic geological evolution dating back to the Precambrian. The chain's present configuration is due to the collision between the microcontinent Iberia and the southwestern promontory of the European Plate. The two continents were approaching each other since the onset of the Upper Cretaceous (Albian/Cenomanian) about 100 million years ago and were consequently colliding during the Paleogene (Eocene/Oligocene) 55 to 25 million years ago. After its uplift, the chain experienced intense erosion and isostatic readjustments. A cross-section through the chain shows an asymmetric flower-like structure with steeper dips on the French side. The Pyrenees are not solely the result of compressional forces, but also show an important sinistral shearing.
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The Morro Solar Group is a stratigraphic group of Mesozoic-aged sedimentary formations exposed near Lima, Peru. The groups formations more specifically of Berriasian and Valanginian age and overlies the Jurassic Puente Piedra Group and underlies the Cretaceous Pamplona Formation. The Morro Solar Group is intruded by sills of andesitic composition. Together with the Casma and Imperial Groups, the Morro Solar Group contains clastic volcanosedimentary material derivative of the Mesozoic Casma Volcanic Arc. The formations of the group hosts mostly local fossils which do not have counterparts for biochronological correlation in other regions.
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