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Gunflint Range
The Gunflint Range is an iron ore deposit in northern Minnesota in the United States and Northwestern Ontario, Canada. The range extends from the extreme northern portion of Cook County, Minnesota into the Thunder Bay District, Ontario. The Gunflint Iron Formation is a continuation of the Mesabi Range to the southwest. The two have been separated by the intrusion of the Duluth Gabbro complex. The iron deposit is a banded iron formation of the Early Proterozoic Animikie Group. The Gunflint Iron Formation is overlain by "brecciated and complexly deformed iron formations", which in turn is overlain by ejecta from the " Sudbury meteorite impact event." This Sudbury Impact Layer is overlain by the Rove Formation. Stromatolite structures are evident within the Gunflint Iron Formation. The cherts of the Gunflint (the Gunflint Chert) are noted for containing Precambrian microfossils. See also *Midcontinent Rift System * Paulson Mine * Cuyuna Range *Vermilion Range (Minnesota) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron Ranges
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in front of oxygen (32.1% and 30.1%, respectively), forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust. In its metallic state, iron is rare in the Earth's crust, limited mainly to deposition by meteorites. Iron ores, by contrast, are among the most abundant in the Earth's crust, although extracting usable metal from them requires kilns or furnaces capable of reaching or higher, about higher than that required to smelt copper. Humans started to master that process in Eurasia during the 2nd millennium BCE and the use of iron tools and weapons began to displace copper alloys, in some regions, only around 1200 BCE. That event is considered the transition from the Bronze Age to the Iron Age. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
History Of The Rove Formation
The Rove Formation, is a sedimentary rock formation of Middle Precambrian age underlying the upper northeastern part of Cook County, Minnesota, United States, and extending into Ontario, Canada. It is the youngest of the many layers of sedimentary rocks which constitute the Animikie Group. Before the Rove sediments were laid down, during the Archean Eon, the Algoman orogeny added landmass along a border from South Dakota to the Lake Huron region; this boundary is the Great Lakes tectonic zone. Several million years later a thin layer of hypervelocity impact ejecta from the Sudbury impact event was deposited on the older, underlying, Gunflint Iron Formation, and the Rove was then deposited on top of the ejecta; it is estimated that at ground zero the earthquake generated by the meteor impact would have registered 10.2 on the Richter scale. During the Middle Precambrian a shallow inland sea covered much of the Lake Superior region and formed the Animikie Group of sedimentary rocks ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of Minnesota
The geology of Minnesota comprises the rock, minerals, and soils of the U.S. state of Minnesota, including their formation, development, distribution, and condition. The state's geologic history can be divided into three periods. The first period was a lengthy period of geologic instability from the origin of the planet until roughly 1,100 million years ago. During this time, the state's Precambrian bedrock was formed by volcanism and the deposition of sedimentary rock and then modified by processes such as faulting, folding and erosion. In the second period, many layers of sedimentary rock were formed by deposition and lithification of successive layers of sediment from runoff and repeated incursions of the sea. In the third and most recent period starting about 1.8 million years ago, glaciation eroded previous rock formations and deposited deep layers of glacial till over most of the state, and created the beds and valleys of modern lakes and rivers. Minnesota's geologic r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marquette Iron Range
The Marquette Iron Range is a deposit of iron ore located in Marquette County, Michigan in the United States. The towns of Ishpeming and Negaunee developed as a result of mining this deposit. A smaller counterpart of Minnesota's Mesabi Range, this is one of two iron ranges in the Lake Superior basin that are in active production as of 2018. The iron ore of the Marquette Range has been mined continuously from 1847 until the present day. Marquette Iron Range is the deposit's popular and commercial name; it is also known to geologists as the Negaunee Iron Formation. History The geology of the district consists of middle Precambrian rocks in the Animikie Group, which form a westward plunging syncline long and wide. The principal iron ore is found in the Negaunee Iron formation. This formation is thick near Negaunee. This is a magnetite or hematite chert. Natural ore deposits are located in synclines and up against mafic dikes. Beneficiation commenced in 1954 and this concentration ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gogebic Range
The Gogebic Range is an elongated area of iron ore deposits located within a range of hills in northern Michigan and Wisconsin just south of Lake Superior. It extends from Lake Namakagon in Wisconsin eastward to Lake Gogebic in Michigan, or almost 80 miles. Though long, it is only about a half mile wide and forms a crescent concave to the southeast. The Gogebic Range includes the communities of Ironwood in Michigan, plus Mellen and Hurley in Wisconsin. The name Gogebic is Ojibwa for "where trout rising to the surface make rings in the water." "Range" is the term commonly used for such iron ore areas around Lake Superior. In Wisconsin, the Gogebic Range is often called the Penokee Range. The range is named after Lake Gogebic, a large lake near the east end of the range in Gogebic and Ontonagon Counties in Michigan. Located within the southern of two parallel prominent ridges, the Gogebic range iron formation name is often used interchangeably with the range of hills that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vermilion Range (Minnesota)
The Vermilion Range exists between Tower, Minnesota and Ely, Minnesota, and contains significant deposits of iron ore. Together with the Mesabi and Cuyuna Ranges, these three constitute the Iron Ranges of northern Minnesota. While the Mesabi Range had iron ore close enough to the surface to enable pit mining, mines had to be dug deep underground to reach the ore of the Vermilion and Cuyuna ranges. The Soudan mine was nearly 1/2 mile underground and required blasting of Precambrian sedimentary bedrock.Jackson, Judy"Notes from Underground" ''Ferminews'', July 19, 2002. The banded iron formation in the range consists of a "interbedded sequence" of chert, magnetite and hematite. Eleven mines operated in the range, with five in the Ely area. The Ely Trough, a synclinal fold, produced 70 million metric tons from the Chandler, Pioneer, Zenith, Sibley and Savoy mines. The largest mine in the range, Soudan, was closed in 1962, and the last mine in the Ely area closed in 1964. Despite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cuyuna Range
The Cuyuna Range is an inactive iron range to the southwest of the Mesabi Range, largely within Crow Wing County, Minnesota. It lies along a line between Brainerd, Minnesota, and Aitkin, Minnesota. The width ranges from 1 to 10 miles (1.6 to 16 km). Discovery Though covered by Pleistocene glacial drift up to 200 feet thick, 1859 surveyors noted compass deflection while in the area. The range was surveyed by Cuyler Adams, using a dip needle in 1895. With partners, he located ore by drilling in 1903. The word "Cuyuna" is an amalgamation of the first three letters of Cuyler's name with "Una", the name of his dog. The Kennedy mine shaft reached ore in April 1908 and the first shipment was made via rail on 11 April 1911. Open pit mining started at the Rowe mine in 1912. In addition to the iron, the ore was rich in manganese, which was useful during World War I, with 32 mines operating. At the height of the mining, the Cuyuna Range was the location of the worst mining disaste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paulson Mine
The Paulson Mine is a former iron ore mine located in Cook County, Minnesota, United States, 53 kilometres north-west of Grand Marais, Minnesota near the end of the historic Gunflint Trail. The Port Arthur, Duluth and Western Railway was built to the mine in 1892 to access the ore, but both the mine and railway failed. Early history The existence of iron bearing rocks in the Gunflint Lake area was first mentioned as early as 1850. Eventually these deposits would be linked to the famous Mesabi Iron Range and this eastern portion which extended into Ontario became known as the Gunflint Range. Conclusive evidence of the quality of iron in the area would not come until 1886 when Grand Marais pioneer Hazael "Henry" Mayhew made discoveries at the western end of the lake. This then attracted the attention of investors in the state capital. In late 1886 an enterprise known as the American Realty Company was incorporated in Minnesota. Several of its promoters had ties to the recently esta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Midcontinent Rift System
The Midcontinent Rift System (MRS) or Keweenawan Rift is a long geological rift in the center of the North American continent and south-central part of the North American plate. It formed when the continent's core, the North American craton, began to split apart during the Mesoproterozoic era of the Precambrian, about 1.1 billion years ago. The rift failed, leaving behind thick layers of igneous rock that are exposed in its northern reaches, but buried beneath later sedimentary formations along most of its western and eastern arms. Those arms meet at Lake Superior, which is contained within the rift valley. The lake's north shore in Ontario and Minnesota defines the northern arc of the rift. From the lake, the rift's eastern arm trends south to central lower Michigan, and possibly into Indiana, Ohio, Kentucky, Tennessee, and Alabama. The western arm runs from Lake Superior southwest through portions of Wisconsin, Minnesota, Iowa, and Nebraska to northeastern Kansas, and po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microfossil
A microfossil is a fossil that is generally between 0.001 mm and 1 mm in size, the visual study of which requires the use of light or electron microscopy. A fossil which can be studied with the naked eye or low-powered magnification, such as a hand lens, is referred to as a macrofossil. Microfossils are a common feature of the geological record, from the Precambrian to the Holocene. They are most common in deposits of marine environments, but also occur in brackish water, fresh water and terrestrial sedimentary deposits. While every kingdom of life is represented in the microfossil record, the most abundant forms are protist skeletons or microbial cysts from the Chrysophyta, Pyrrhophyta, Sarcodina, acritarchs and chitinozoans, together with pollen and spores from the vascular plants. Overview A microfossil is a descriptive term applied to fossilized plants and animals whose size is just at or below the level at which the fossil can be analyzed by the naked eye. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precambrian
The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic Eon, which is named after Cambria, the Latinised name for Wales, where rocks from this age were first studied. The Precambrian accounts for 88% of the Earth's geologic time. The Precambrian is an informal unit of geologic time, subdivided into three eons ( Hadean, Archean, Proterozoic) of the geologic time scale. It spans from the formation of Earth about 4.6 billion years ago ( Ga) to the beginning of the Cambrian Period, about million years ago ( Ma), when hard-shelled creatures first appeared in abundance. Overview Relatively little is known about the Precambrian, despite it making up roughly seven-eighths of the Earth's history, and what is known has largely been discovered from the 1960s onwards. The Precambrian fossil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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