Geology and Minerals

Central Montana Alkalic Province

The central Montana Alkalic Province is located in the United States in central Montana. Montana is bordered by Idaho, Wyoming, North Dakota, South Dakota, and Canada to the north. Central Montana is unique when compared to the rest of the Rocky Mountains due to its east-west trend of tectonic features, including thrust fault zones, anticlines, and domes. The area of tectonic activity experienced conditions of plastic deformation, which affected the whole region. The Montana Alkalic Province consist of Cretaceous intrusions of monzonite and syenite as well as Cambrian limestone, sandstone, and siltstone. Most of the sedimentary rocks are a result of deposition from a terrestrial fluvial environment. Deposition included more than 13,000 feet of clastics that were later uplifted. The peak of this uplifting occurred during the Devonian. Deposition, uplift, and traps of carbonate shales have made central Montana prime for small-scale oil and gas production. Other geologic formations in this area include Judith Mountains, Crazy Mountains, Highwood Mountains, and Bears Paw Mountains. These areas include various igneous formations including xenoliths, laccoliths, and veins. Each mountain exhibits similar but unique geologic features.

Also on this shelf

See also

• ▸Bend Arch–Fort Worth Basin
• ▸Davidic line
• ▸Earth's crust

Uncatalogued shelf

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