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Paleoproterozoic Magmatism
The Paleoproterozoic Era (;, also spelled Palaeoproterozoic), spanning the time period from (2.5–1.6 Year, Ga), is the first of the three sub-divisions (era (geology), eras) of the Proterozoic Eon. The Paleoproterozoic is also the longest era of the Earth's geological history of Earth, 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 Great Oxygenation Event, 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 l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stromatolites
Stromatolites () or stromatoliths () are layered sedimentary formations (microbialite) that are created mainly by photosynthetic microorganisms such as cyanobacteria, sulfate-reducing bacteria, and Pseudomonadota (formerly proteobacteria). These microorganisms produce adhesive compounds that cement sand and other rocky materials to form mineral " microbial mats". In turn, these mats build up layer by layer, growing gradually over time. A stromatolite may grow to a meter or more. Although they are rare today, fossilized stromatolites provide records of ancient life on Earth. Morphology Stromatolites are layered, biochemical, accretionary structures formed in shallow water by the trapping, binding and cementation of sedimentary grains in biofilms (specifically microbial mats), through the action of certain microbial lifeforms, especially cyanobacteria. They exhibit a variety of forms and structures, or morphologies, including conical, stratiform, domal, columnar, and branchin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Francevillian Biota
The Francevillian biota (also known as Gabon macrofossils or Gabonionta) is a group of 2.1-billion-year-old Palaeoproterozoic, macroscopic organisms known from fossils found in Gabon in the Palaeoproterozoic Francevillian B Formation, a black shale province. The fossils are postulated to be evidence of the earliest form of multicellular life. They were discovered by an international team led by the Moroccan-French geologist Abderrazak El Albani, of the University of Poitiers, France. While they have yet to be assigned to a formal taxonomic position, they have been informally and collectively referred to as the "Gabonionta" by the Natural History Museum Vienna in 2014. Morphology The fossil organisms are up to in size. Their bodies were flattened disks with a characteristic morphology, including circular and elongated individuals. A spherical to ellipsoidal central body is bounded by radial structures. The fossils show three-dimensionality and coordinated growth. Cell-cel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Akitkan Orogen
The Akitkan Range (russian: хребет Акиткан; zh, 阿基特坎山) is a mountain range in Irkutsk Oblast and Buryatia, Russian Federation.Google Earth The Paleoproterozoic Akitkan Orogen is named after the range. History Between 1855 and 1858 Ivan Kryzhin (d. 1884) took part in the Eastern Siberian expedition led by Russian astronomer and traveler Ludwig Schwarz. In 1857 he mapped the Kirenga River and, while exploring its right tributary, the Cherepanikha, Kryzhin discovered the formerly unknown Akitkan Range rising above the area of its source. The North Baikal Highlands, where the range rises, were explored between 1909 and 1911 by Russian geologist Pavel Preobrazhensky (1874 - 1944). He surveyed the river valley of the Chechuy, a right tributary of the Lena with its sources in the Akitkan. Overcoming numerous difficulties, Preobrazhensky managed to map for the first time a stretch of the Akitkan Range. Geography The Akitkan stretches roughly northwards for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Svecofennian Orogeny
The Svecofennian orogeny is a series of related orogenies that resulted in the formation of much of the continental crust in what is today Sweden and Finland plus some minor parts of Russia. The orogenies lasted from about 2000 to 1800 million years ago during the Paleoproterozoic Era. The resulting orogen is known as the Svecofennian orogen or Svecofennides. To the west and southwest the Svecofennian orogen limits with the generally younger Transscandinavian Igneous Belt. It is assumed that the westernmost fringes of the Svecofennian orogen have been reworked by the Sveconorwegian orogeny just as the western parts of the Transscandinavian Igneous Belt has. The Svecofennian orogeny involved the accretion of numerous island arcs in such manner that the pre-existing craton grew with this new material from what is today northeast to the southwest. The accretion of the island arcs was also related to two other processes that occurred in the same period; the formation of magma tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nagssugtoqidian Orogeny
The Nagssugtoqidian orogeny was a late Paleoproterozoic mountain-building event that affected Greenland during the period 1.91 to 1.77 Ga. The orogenic belt formed during this event marks the northern boundary of the mainly Archaean North Atlantic Craton. It was first recognised by Ramberg in 1949, based on its effect on the Kangaamiut dike swarm. The subsequent recognition of magmatic terranes representing past island arcs and two potential sutures representing now vanished subduction zones within the belt, have enabled its interpretation in terms of plate tectonics Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large te .... References {{Reflist Orogenies of North America Proterozoic North America Geology of Greenland Paleoproterozoic orogenies ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torngat Mountains
The Torngat Mountains are a mountain range on the Labrador Peninsula at the northern tip of Newfoundland and Labrador and eastern Quebec. They are part of the Arctic Cordillera.Park Wardens - Arctic Cordillera The mountains form a peninsula that separates from the . Etymology The name ''Torngat'' is derived from an word meaning ''place of spirits'', sometimes interpreted as ''place of evil spirits''.[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ungava Magmatic Event
The Ungava magmatic event was a widespread magmatic event that began about 2.22 billion years ago during the Proterozoic Eon. Extent With an area of , the Ungava magmatic event caused the formation of a large igneous province. Magmatic features that were formed during the Ungava magmatic event include the Klotz, Maguire and Senneterre dikes of Quebec and the Nipissing sills of Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca .... References Igneous petrology of Quebec Igneous petrology of Ontario Paleoproterozoic magmatism {{Canada-geology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wopmay Orogen
The Wopmay orogen is a Paleoproterozoic orogenic belt in northern Canada which formed during the collision between the Hottah terrane (north of the Hottah Lake), a continental magmatic arc, and the Archean Slave Craton at about 1.88 Ga (billion years). The collision lead to the short-lived Calderian orogeny. The formation was named for Wilfrid Reid "Wop" May, OBE, DFC (April 20, 1896 – June 21, 1952), a Canadian flying ace in the First World War and a leading post-war aviator. It is approximately 500 km along the north–south axis, and 200 km along the east–west axis at its widest point, tapering at both the northern and southern ends. Geological setting The Wopmay orogen can be subdivided into (east to west): a passive continental margin, the Wopmay fault zone, the Great Bear magmatic zone, and the Hottah terrane. The passive margin developed around 1970–1890 Ma on-top of the Slave Craton. The Wopmay fault zone is probably a suture betwee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Penokean Orogeny
The Penokean orogeny was a mountain-building episode that occurred in the early Proterozoic about 1.86 to 1.83 billion years ago, in the area of Lake Superior, North America. The core of this orogeny, the Churchill Craton, is composed of terranes derived from the 1.86–1.81 Ga collision between the Superior and North Atlantic cratons. The orogeny resulted in the formation of the Nena and Arctica continents, which later merged with other continents to form the Columbia supercontinent. The name was first proposed by in reference to what is known as the Penokee Range, sometimes incorrectly called the Gogebic Range, in northern Michigan and Wisconsin. The Paleoproterozoic Penokean orogeny developed in an embayment on the southern margin of the Superior Craton. It extends east from Minnesota to the Grenville orogen near Lake Huron and south to the Central Plain in Wisconsin. It is composed of two domains separated by the Niagara Fault Zone: the southern, internal domain, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trans-Hudson Orogeny
The Trans-Hudson orogeny or Trans-Hudsonian orogeny was the major mountain building event (orogeny) that formed the Precambrian Canadian Shield and the North American Craton (also called Laurentia), forging the initial North American continent. It gave rise to the Trans-Hudson orogen (THO), or Trans-Hudson Orogen Transect (THOT), (also referred to as the Trans-Hudsonian Suture Zone (THSZ) or Trans-Hudson suture) which is the largest Paleoproterozoic orogenic belt in the world. It consists of a network of belts that were formed by Proterozoic crustal accretion and the collision of pre-existing Archean continents. The event occurred 2.0–1.8 billion years ago. The Trans-Hudson orogen sutured together the Hearne- Rae, Superior, and Wyoming cratons to form the cratonic core of North America in a network of Paleoproterozoic orogenic belts. These orogenic belts include the margins of at least nine independent microcontinents that were themselves sections of at least three forme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limpopo Belt
The Limpopo Belt is located in South Africa and Zimbabwe, runs E-NE, and joins the Kaapvaal Craton to the south with the Zimbabwe Craton to the north. The belt is of high-grade metamorphic rocks that have undergone a long cycle of metamorphism and deformation that ended 2.0 billion years ago, after the stabilisation of the adjacent massifs. The belt comprises 3 components: the Central Zone, the North Marginal Zone and the South Marginal Zone. Ca. 3.2-2.9 Ga Limpopo Central Zone The 250 km wide Limpopo belt of southern Africa is an east-northeast trending zone of granulite facies tectonites separating the granitoid-greenstone terranes of the Kaapvaal and Zimbabwe cratons. Large scale ductile shear zones are an integral part of Limpopo belt architecture. They define the boundaries between the belt and the adjacent cratons and separate internal zones within the belt. The shear zones forming the external (northern, southern and western) margins of the belt are interpreted as uplif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orogeny
Orogeny is a mountain building process. An orogeny is an event that takes place at a convergent plate margin when plate motion compresses the margin. An '' orogenic belt'' or ''orogen'' develops as the compressed plate crumples and is uplifted to form one or more mountain ranges. This involves a series of geological processes collectively called orogenesis. These include both structural deformation of existing continental crust and the creation of new continental crust through volcanism. Magma rising in the orogen carries less dense material upwards while leaving more dense material behind, resulting in compositional differentiation of Earth's lithosphere ( crust and uppermost mantle). A synorogenic process or event is one that occurs during an orogeny. The word "orogeny" () comes from Ancient Greek (, , + , , ). Although it was used before him, the term was employed by the American geologist G. K. Gilbert in 1890 to describe the process of mountain-building as distinguis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
