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Stikine Terrane
Stikinia, or the Stikine terrane, is a terrane in British Columbia, Canada; the largest of the Canadian Cordillera. It formed as an independent, intraoceanic volcanic arc during the Paleozoic and Mesozoic. Stikinia forms the bedrock of numerous volcanoes in the southern portion of the Northern Cordilleran Volcanic Province (NCVP), a Miocene to Holocene geologic province that has its origins in continental rifting. Extent Until recently the Paleozoic rocks that form a non-continuous belt along the western margin of the NCVP (the Stikine assemblage) were only recognized in a restricted area in northern British Columbia, between the Stikine River and Taku River areas. In contrast, Mesozoic Stikinia rocks form a near-continuous belt that extends much farther to the north, leading some authors to question the nature of the unexposed Paleozoic basement north of the Taku River area. The following correlations have significant implications for tectonic reconstructions of the northern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terrane
In geology, a terrane (; 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 surrounding areas—hence the term "exotic" terrane. The suture zone between a terrane and the crust it attaches to is usually identifiable as a fault. A sedimentary deposit that buries the contact of the terrane with adjacent rock is called an overlap formation. An igneous intrusion that has intruded and obscured the contact of a terrane with adjacent rock is called a stitching pluton. There is also an older usage of the term ''terrane'', which described a series of related rock formations or an area with a preponderance of a particular rock or rock group. Overview A tectonostratigraphic terrane did not necessarily originate as an independent microplate, since it may not contain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intrusion
In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and compositions, illustrated by examples like the Palisades Sill of New York and New Jersey; the Henry Mountains of Utah; the Bushveld Igneous Complex of South Africa; Shiprock in New Mexico; the Ardnamurchan intrusion in Scotland; and the Sierra Nevada Batholith of California. Because the solid country rock into which magma intrudes is an excellent insulator, cooling of the magma is extremely slow, and intrusive igneous rock is coarse-grained ( phaneritic). Intrusive igneous rocks are classified separately from extrusive igneous rocks, generally on the basis of their mineral content. The relative amounts of quartz, alkali feldspar, plagioclase, and feldspathoid is particularly important in classifying intrusive igneous rocks. Intrusio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesozoic Volcanism
The Mesozoic Era is the era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Periods. It is characterized by the dominance of archosaurian reptiles such as the dinosaurs, and of gymnosperms such as cycads, ginkgoaceae and araucarian conifers; a hot greenhouse climate; and the tectonic break-up of Pangaea. The Mesozoic is the middle of the three eras since complex life evolved: the Paleozoic, the Mesozoic, and the Cenozoic. The era began in the wake of the Permian–Triassic extinction event, the largest mass extinction in Earth's history, and ended with the Cretaceous–Paleogene extinction event, another mass extinction whose victims included the non-avian dinosaurs, pterosaurs, mosasaurs, and plesiosaurs. The Mesozoic was a time of significant tectonic, climatic, and evolutionary activity. The supercontinent Pangaea began to break apart into separate landmasses. The climate of the Mesozoic was varied, alternating between ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleozoic Volcanism
The Paleozoic ( , , ; or Palaeozoic) Era is the first of three geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma at the start of the Mesozoic Era. The Paleozoic is subdivided into six geologic periods (from oldest to youngest), Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian. Some geological timescales divide the Paleozoic informally into early and late sub-eras: the Early Paleozoic consisting of the Cambrian, Ordovician and Silurian; the Late Paleozoic consisting of the Devonian, Carboniferous and Permian. The name ''Paleozoic'' was first used by Adam Sedgwick (1785–1873) in 1838 to describe the Cambrian and Ordovician periods. It was redefined by John Phillips (1800–1874) in 1840 to cover the Cambrian to Permian periods. It is derived from the Greek ''palaiós'' (παλαιός, "old") and ''zōḗ'' (ζωή, "life") meaning "ancient lif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of Yukon
The geology of Yukon includes sections of ancient Precambrian Proterozoic rock from the western edge of the proto-North American continent Laurentia, with several different island arc terranes added through the Paleozoic, Mesozoic and Cenozoic, driving volcanism, pluton formation and sedimentation. Geologic History, Stratigraphy & Tectonics The rocks of eastern Yukon, together with those in neighboring British Columbia and Northwest Territories formed beginning more than 1.7 billion years ago in the Proterozoic. The region was at the western edge of the proto-North American continent Laurentia and in the uplifted mountains of the North American Cordillera, preserves one of the longest sedimentary records in the world. Proterozoic sediments are known from inliers within the more dominant Paleozoic rocks. The 13-kilometer Wernecke Supergroup deposited between cratons with siliciclastic and carbonate rocks. Breccia remains from volcanic eruptions 1.7 billion years ago in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of British Columbia
The geology of British Columbia is a function of its location on the leading edge of the North American continent. The mountainous physiography and the diversity of the different types and ages of rock hint at the complex geology, which is still undergoing revision despite a century of exploration and mapping. The province's most prominent geological features are its mountain ranges, including the North American Cordillera which stretches from Southern Mexico to Alaska. Terrane theory Terrane theory was first proposed by Jim Monger of the Geological Survey of Canada and Charlie Rouse in 1971 as an explanation for a set of fusulinid fossils that were found in central British Columbia. Rather than suggest that facies changes or seaways were behind this (which were common explanations at the time), the two geologists proposed that the fossils in question had been part of an assemblage of rocks that had migrated across the Pacific Ocean to their present location. This theor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metamorphic Rock
Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock ( protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causing profound physical or chemical changes. During this process, the rock remains mostly in the solid state, but gradually recrystallizes to a new texture or mineral composition. The protolith may be an igneous, sedimentary, or existing metamorphic rock. Metamorphic rocks make up a large part of the Earth's crust and form 12% of the Earth's land surface. They are classified by their protolith, their chemical and mineral makeup, and their texture. They may be formed simply by being deeply buried beneath the Earth's surface, where they are subject to high temperatures and the great pressure of the rock layers above. They can also form from tectonic processes such as continental collisions, which cause horizontal pressure, friction, and dist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aishihik Lake
Aishihik Lake is a lake in southwestern Yukon, Canada. Yukon Electric Corporation operates a 37 megawatt hydroelectric dam, built in 1975, at the south end of the lake, where it drains southward into the Aishihik River. A US Air Force base was established near the north part of the lake during World War II. The base used two Buda diesel engines to supply power and pump water. Fauna Northern Mountain caribou The Aishihik and Kluane caribou herds migrate in the area surrounding Kluane and Aishihik Lakes. They are a northern mountain caribou, a distinct ecotype of the woodland caribou. In 2009 there were 181 caribou in the Kluane herd (also known as the Burwash herd) and 2,044 caribou in the Aishihik herd. The Kluane herd was declining while the Aishihik herd was increasing. Wood Bison A 2020 Government of Yukon report stated that an estimated 50% of the territory's wood bison population lived in a core range centered on this lake and stretching east the Klondike Highway, so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. The Jurassic constitutes the second and middle period of the Mesozoic, Mesozoic Era as well as the eighth period of the Phanerozoic, Phanerozoic Eon and is named after the Jura Mountains, where limestone strata from the period were first identified. The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic magmatic province, Central Atlantic Magmatic Province (CAMP). The beginning of the Toarcian Age started around 183 million years ago and is marked by the Toarcian Oceanic Anoxic Event, a global episode of Anoxic event, oceanic anoxia, ocean acidification, and elevated global temperatures associated with extinctions, likely caused by the eruption of the Kar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tagish Lake
Tagish Lake is a lake in Yukon and northern British Columbia, Canada. The lake is long and averages wide with an area of , about two thirds of which is in British Columbia. The average depth is and maximum depth is . It has two arms, the Taku Arm in the east which is very long and mostly in British Columbia and Windy Arm in the west, mostly in Yukon. The Klondike Highway runs along Windy Arm south of Carcross. Bennett Lake flows into Tagish Lake, so the northern portion of Tagish Lake was part of the route to the Klondike used by gold-seekers during the Klondike Gold Rush. The meteorite On January 18, 2000, a carbonaceous chondrite meteorite now known as " Tagish Lake", fell on the frozen surface of the Taku Arm. A number of fragments were recovered and studied by researchers from the University of Calgary, University of Western Ontario, and NASA; the meteorite currently resides in the University of Alberta meteorite collection. The name The lake is named for the Tagish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boundary Ranges
The Boundary Ranges, also known in the singular and as the Alaska Boundary Range, are the largest and most northerly subrange of the Coast Mountains. They begin at the Nass River, near the southern end of the Alaska Panhandle in the Canadian province of British Columbia and run to the Kelsall River, near the Chilkoot Pass, beyond which are the Alsek Ranges of the Saint Elias Mountains, and northwards into the Yukon Territory flanking the west side of the Yukon River drainage as far as Champagne, Yukon, Champagne Pass, north of which being the Yukon Ranges. To their east are the Skeena Mountains and Stikine Plateau of the Interior Mountains complex that lies northwest of the Interior Plateau; the immediately adjoining subregion of the Stikine Plateau is the Tahltan Highland. To their northeast is the Tagish Highland, which is a subregion of the Yukon Plateau. Both highlands are considered in some descriptions as included in the Coast Mountains. The Alexander Archipelago lies of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
