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In geology, a terrane (/ t ə ˈ r eɪ n, ˈ t ɛr eɪ n /; [1] [2] in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or "sutured" to crust lying on another plate. The crustal block or fragment preserves its distinctive geologic history, which is different from the ...
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The Yakutat Terrane is currently colliding with the continental margin below the central Gulf of Alaska. During the Neogene the terrane's western part was subducted after which a sediment wedge accreted along the northeast Aleutian Trench. This wedge incorporates sediment eroded from the continental margin and marine sediments carried into the ...
Rocks of Wrangellia (the individual terrane, not the composite terrane) were originally created in the Pennsylvanian to the Jurassic somewhere, but probably near the equator, in the Panthalassic Ocean off the west coast of Laurentia (North American craton) as island arcs, oceanic plateaus, and rock assemblages of the associated tectonic settings.
Initially, Arkansas bauxite met 90% of US aluminum demand. Underground mining before and during World War II gave way to open pit mining in the 1960s. During the war, up to six million tons were mined in 1943. Arkansas bauxite mines were often passed over in favor of higher quality bauxite reserves in the Caribbean and mining ceased in 1982.
Arkansas (/ ˈ ɑːr k ən s ɔː / ⓘ AR-kən-saw [c]) is a landlocked state in the West South Central region of the Southern United States. [9] [10] It borders Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the south, Texas to the southwest, and Oklahoma to the west.
Geologic map of the St. Francois Mountain region. The St. Francois Mountains were formed by volcanic and intrusive activity 1.485 billion (1.485 x 10 9) years ago. [6] By comparison, the Appalachians started forming about 460 million years ago, and the Rockies a mere 140 million years ago.
Laurentia basement rocks. Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of North America.Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, although originally it also included the cratonic areas of Greenland and the Hebridean Terrane in northwest Scotland.