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Grenville Province
The Grenville Province is a tectonically complex region, in Eastern Canada, that contains many different aged accreted terranes from various origins. It exists southeast of the Grenville Front and extends from Labrador southwestern to Lake Huron. It is bounded by the St. Lawrence River/ Seaway to the southeast. The Grenville Front separates the Grenville Province from the Superior Craton. Adjacent to the Grenville Front is the Parautochthonous Belt. The Parautochthonous Belt is made of rocks originally derived from the Superior Craton, which have been metamorphosed and reworked since their emplacement. The rocks to the southwest of the Parautochthonous Belt are various accreted terranes that have been thrust upon or emplaced during the various tectonic events that have taken place from 2.0-0.98 billion years ago. The compositions of these terranes are unique and have distinct depleted mantle model ages. During the formation of the Grenville Province, the type of tectonism change ... [...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 own distinctive geologic history, which is different from that of 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. Older usage of ''terrane'' simply described a series of related rock formations or an area having a preponderance of a particular rock or rock groups. Overview A tectonostratigraphic terrane is not necessarily an independent microplate in origin, since it may not contain the full thickness ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baie-Comeau
Baie-Comeau (; 2021 city population 20,687; CA population 26,643) is a city located approximately north-east of Quebec City in the Côte-Nord region of the province of Quebec, Canada. It is located on the shores of the Saint Lawrence River near the mouth of the Manicouagan River, and is the seat of Manicouagan Regional County Municipality. There are two urban area population centres within the city limits: Baie-Comeau proper, with a population of 9,100, and Hauterive, with a population of 11,147, as of the 2021 Canadian Census. The city is named after the adjacent Comeau Bay, which is named in honour of Napoléon-Alexandre Comeau, a Québécois naturalist. Baie-Comeau is the birthplace of former Prime Minister of Canada Brian Mulroney. History The oldest part of Baie-Comeau is the area known as ''Vieux-Poste'' (Old Post) near the mouth of the Amédée River where in 1889, the Saint-Eugène-de-Manicouagan Mission was founded by Eudists. In 1898, the first sawmill in the Côte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mylonite
Mylonite is a fine-grained, compact metamorphic rock produced by dynamic recrystallization of the constituent minerals resulting in a reduction of the grain size of the rock. Mylonites can have many different mineralogical compositions; it is a classification based on the textural appearance of the rock. Formation Mylonites are ductilely deformed rocks formed by the accumulation of large shear strain, in ductile fault zones. There are many different views on the formation of mylonites, but it is generally agreed that crystal-plastic deformation must have occurred, and that fracturing and cataclastic flow are secondary processes in the formation of mylonites. Mechanical abrasion of grains by milling does not occur, although this was originally thought to be the process that formed mylonites, which were named from the Greek μύλος ''mylos'', meaning mill. Mylonites form at depths of no less than 4 km. There are many different mechanisms that accommodate crystal-plastic def ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laurentia
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 also the northwestern part of Scotland, known as the Hebridean Terrane. During other times in its past, Laurentia has been part of larger continents and supercontinents and itself consists of many smaller terranes assembled on a network of Early Proterozoic orogenic belts. Small microcontinents and oceanic islands collided with and sutured onto the ever-growing Laurentia, and together formed the stable Precambrian craton seen today. The craton is named after the Laurentian Shield, through the Laurentian Mountains, which received their name from the Saint Lawrence River, named after Lawrence of Rome. Interior platform In eastern and central Canada, much of the stable craton is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flat Slab Subduction
Flat slab subduction is characterized by a low subduction angle (<30 degrees to horizontal) beyond the and a resumption of normal subduction far from the . A slab refers to the subducting lower . Although, some would characterize flat slab as any shallowly dipping lower plate as in western ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesoproterozoic
The Mesoproterozoic Era is a geologic era that occurred from . The Mesoproterozoic was the first era of Earth's history for which a fairly definitive geological record survives. Continents existed during the preceding era (the Paleoproterozoic), but little is known about them. The continental masses of the Mesoproterozoic were more or less the same ones that exist today, although their arrangement on the Earth's surface was different. Major events and characteristics The major events of this era are the breakup of the Columbia supercontinent, the formation of the Rodinia supercontinent, and the evolution of sexual reproduction. This era is marked by the further development of continental plates and plate tectonics. The supercontinent of Columbia broke up between 1500 and 1350 million years ago, and the fragments reassembled into the supercontinent of Rodinia around 1100 to 900 million years ago, on the time boundary between the Mesoproterozoic and the subsequent Neoproterozoi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleoproterozoic
The Paleoproterozoic Era (;, also spelled Palaeoproterozoic), spanning the time period from (2.5–1.6 Ga), is the first of the three sub-divisions (eras) of the Proterozoic Eon. The Paleoproterozoic is also the longest era of the Earth's geological history. It was during this era that the continents first stabilized. Paleontological evidence suggests that the Earth's rotational rate ~1.8 billion years ago equated to 20-hour days, implying a total of ~450 days per year. Atmosphere Before the enormous increase in atmospheric oxygen, almost all existing lifeforms were anaerobic organisms whose metabolism was based on a form of cellular respiration that did not require oxygen. Free oxygen in large amounts is toxic to most anaerobic organisms. Consequently, most died when the atmospheric free oxygen levels soared in an extinction event called the Great Oxidation Event, which brought atmospheric oxygen levels to up to 10% of their current level. The only creatures that survi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indenter Tectonics
Indenter tectonics, also known as escape tectonics, is a branch of strike-slip tectonics that involves the collision and deformation of two continental plates. It can be observed in many situations around the world, and is associated with high-grade metamorphism and extensive lateral displacement of strata along oblique strike-slip faults Model The concept of indenter tectonics was first introduced by Molnar and Tapponnier in 1975, with reference to the Himalayan orogeny. Various experiments have illustrated the process by which deformation occurs. A continent-continent collision can be visualized as a 'die-and-metal' model, with a rigid die (the 'indenter') moving into a softer, rigid-plastic metal (the 'host'). In a tectonic setting, the terms ‘rigid’ and ‘soft’ refer to the strength of the lithosphere. The strong lithosphere of the indenter remains relatively undeformed and its boundaries are preserved, while the host allows deformation by lateral movement of crus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nappe
In geology, a nappe or thrust sheet is a large sheetlike body of rock (geology), rock that has been moved more than or above a thrust fault from its original position. Nappes form in compressional tectonic settings like continental collision zones or on the overriding plate in active subduction zones. Nappes form when a mass of rock is forced (or thrust fault, "thrust") over another rock mass, typically on a low angle fault plane. The resulting structure may include large-scale recumbent Fold (geology), folds, shearing along the fault plane,Twiss, Robert J. and Eldridge M. Moores, ''Structural Geology,'' W. H. Freeman, 1992, p. 236 Thrust fault#Thrust duplex, imbricate thrust stacks, Window (geology), fensters and klippes. The term stems from the French word for ''tablecloth'' in allusion to a rumpled tablecloth being pushed across a table. History Nappes or nappe belts are a major feature of the European Geology of the Alps, Alps, Dinaric Alps, Dinarides, Carpathians and S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Georgian Bay
Georgian Bay (french: Baie Georgienne) is a large bay of Lake Huron, in the Laurentia bioregion. It is located entirely within the borders of Ontario, Canada. The main body of the bay lies east of the Bruce Peninsula and Manitoulin Island. To its northwest is the North Channel. Georgian Bay is surrounded by (listed clockwise) the districts of Manitoulin, Sudbury, Parry Sound and Muskoka, as well as the more populous counties of Simcoe, Grey and Bruce. The Main Channel separates the Bruce Peninsula from Manitoulin Island and connects Georgian Bay to the rest of Lake Huron. The North Channel, located between Manitoulin Island and the Sudbury District, west of Killarney, was once a popular route for steamships and is now used by a variety of pleasure craft to travel to and from Georgian Bay. The shores and waterways of the Georgian Bay are the traditional domain of the Anishinaabeg First Nations peoples to the north and Huron-Petun (Wyandot) to the south. The bay was thus a ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Migmatite
Migmatite is a composite rock found in medium and high-grade metamorphic environments, commonly within Precambrian cratonic blocks. It consists of two or more constituents often layered repetitively: one layer is an older metamorphic rock that was reconstituted subsequently by partial melting ("paleosome"), while the alternate layer has a pegmatitic, aplitic, granitic or generally plutonic appearance ("neosome"). Commonly, migmatites occur below deformed metamorphic rocks that represent the base of eroded mountain chains. Migmatites form under extreme temperature and pressure conditions during prograde metamorphism, when partial melting occurs in metamorphic paleosome. Components exsolved by partial melting are called neosome (meaning ‘new body’), which may or may not be heterogeneous at the microscopic to macroscopic scale. Migmatites often appear as tightly, incoherently folded veins ( ptygmatic folds).Recommendations by the IUGS Subcommission on the Systematics of M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forestville, Quebec
Forestville is a town in the Côte-Nord region of Quebec, Canada. It is located on the north shore of the Saint Lawrence River along Route 138, approximately southwest of Baie-Comeau. There is a vehicle and passenger ferry service from Forestville to Rimouski, on the south shore of the St. Lawrence that is over wide at this point. The city operates the Forestville Airport. Forestville is known for its hunting and fishing: moose hunting season is popular and there are many lakes and rivers to fish in as well as beaches and camping spots for the summer and cross country skiing in the winter. It is also host to the Boréal Loppet which is a cross-country skiing race with varying distances including 60 km. It also hosted the longest cross-country ski race in the world, at 103 km, from 2005 to 2011. History The area was well known to the First Nations, while the first European settlers arrived in 1844 following the construction of a sawmill by Edward Selvin, of Les Éboul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
