|
Picuris Orogeny
The Picuris orogeny was an orogenic event in what is now the Southwestern United States from 1.43 to 1.3 billion years ago in the Calymmian Period of the Mesoproterozoic. The event is named for the Picuris Mountains in northern New Mexico and interpreted either as the suturing of the Granite-Rhyolite crustal province to the southern margin of the proto-North American continent Laurentia or as the final suturing of the Mazatzal crustal province onto Laurentia. According to the former hypothesis, this was the second in a series of orogenies within a long-lived convergent boundary along southern Laurentia that ended with the ca. 1200–1000 Mya Grenville orogeny during the final assembly of the supercontinent Rodinia, which ended an 800-million-year episode of convergent boundary tectonism. Description Age and isotope data show that southern North America is composed of a series of northeast-trending provinces representing island arc terranes accreted onto the 1800 Mya core of La ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pilar Formation Outcrop
Pilar, Portuguese and Spanish for pillar, may refer to: People * Pilar (given name), a common abbreviation of ''María del Pilar'', including a list of people so named * Pilar (surname), a list of people surnamed Pilar or del Pilar Places Argentina * Barrio El Pilar, a village and municipality in Río Negro Province * Pilar, Buenos Aires, city in Buenos Aires Province * Pilar, Córdoba, city in Córdoba Province * Pilar Partido, a partido located in Greater Buenos Aires in Buenos Aires Province * Pilar, Santa Fe, town in Santa Fe Province Brazil * Pilar, Alagoas * Pilar, Paraíba * Pilar de Goiás, Goiás * Pilar do Sul, São Paulo Philippines * Pilar, Abra, a 5th class municipality * Pilar, Bataan, a 3rd class municipality * Pilar, Bohol, a 4th class municipality * Pilar, Capiz, a 4th class municipality * Pilar, Cebu, a 5th class municipality * Pilar, Sorsogon, a 1st class municipality * Pilar, Surigao del Norte, a 5th class municipality Elsewhere * El Pilar, an anc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Back-arc Basin
A back-arc basin is a type of geologic Structural basin, basin, found at some convergent boundary, convergent plate boundaries. Presently all back-arc basins are submarine features associated with island arcs and subduction zones, with many found in the western Pacific Ocean. Most of them result from Tension (physics), tensional forces, caused by a process known as Oceanic trench#Trench rollback, oceanic trench rollback, where a subduction zone moves towards the subducting plate. Back-arc basins were initially an unexpected phenomenon in plate tectonics, as convergent boundaries were expected to universally be zones of compression. However, in 1970, Dan Karig published a model of back-arc basins consistent with plate tectonics. Structural characteristics Back-arc basins are typically very long and relatively narrow, often thousands of kilometers long while only being a few hundred kilometers wide at most. For back-arc extension to form, a subduction zone is required, but not a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precambrian
The Precambrian ( ; or pre-Cambrian, sometimes abbreviated pC, 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 Latinized 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
East Antarctica
East Antarctica, also called Greater Antarctica, constitutes the majority (two-thirds) of the Antarctic continent, lying primarily in the Eastern Hemisphere south of the Indian Ocean, and separated from West Antarctica by the Transantarctic Mountains. It is generally greater in elevation than West Antarctica, and includes the Gamburtsev Mountain Range in the center. The geographic South Pole is located within East Antarctica. Apart from small areas of the coast, East Antarctica is permanently covered by ice and it has relatively low biodiversity, with only a small number of species of terrestrial plants, animals, algae, and lichens. The coasts are the breeding ground for various seabirds and penguins, and the leopard seal, Weddell seal, elephant seal, crabeater seal and Ross seal breed on the surrounding pack ice in summer. Location and description Almost completely covered in thick, permanent ice, East Antarctica comprises Coats Land, Queen Maud Land, Enderby Land, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SWEAT (hypothesis)
SWEAT (which stands for Southwestern United States and East Antarctica) is the hypothesis that the Southwestern United States was at one time connected to East Antarctica. The hypothesis of a late Precambrian fit of western North America with the Australia-Antarctic shield region permits the extension of many features through Antarctica and into other parts of Gondwana. For example, the Grenville orogen may extend around the coast of East Antarctica into India and Australia, and the ophiolitic belt of the latter may extend into East Antarctica. The Wopmay orogen of northwest Canada may extend through eastern Australia into Antarctica and thence beneath the ice to connect with the Yavapai- Mazatzal orogens of the southwestern United States. Counterparts of the Precambrian-Paleozoic sedimentary rocks along the U.S. Cordilleran miogeocline may be present in the Transantarctic Mountains. Orogen boundaries provide useful piercing points for Precambrian continental reconstructions. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baltica
Baltica is a paleocontinent that formed in the Paleoproterozoic and now constitutes northwestern Eurasia, or Europe north of the Trans-European Suture Zone and west of the Ural Mountains. The thick core of Baltica, the East European Craton, is more than three billion years old and formed part of the Rodinia supercontinent at 1 . Tectonic history Baltica formed at 2.0–1.7 Ga by the collision of three Archaean-Proterozoic continental blocks: Fennoscandia (including the exposed Baltic Shield), Sarmatia ( Ukrainian Shield and Voronezh Massif), and Volgo-Uralia (covered by younger deposits). Sarmatia and Volgo-Uralia formed a proto-craton (sometimes called "Proto-Baltica") at c. 2.0 Ga which collided with Fennoscandia c. 1.8–1.7 Ga. The sutures between these three blocks were reactivated during the Mesoproterozoic and Neoproterozoic. Between 750 and 600 million years ago, Baltica and Laurentia rotated clockwise together and drifted away from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Norwegian Journal Of Geology
Norwegian, Norwayan, or Norsk may refer to: *Something of, from, or related to Norway, a country in northwestern Europe *Norwegians, both a nation and an ethnic group native to Norway *Demographics of Norway *Norwegian language, including the two official written forms: **Bokmål, literally "book language", used by 85–90% of the population of Norway **Nynorsk, literally "New Norwegian", used by 10–15% of the population of Norway *Norwegian Sea Norwegian or may also refer to: Norwegian *Norwegian Air Shuttle, an airline, trading as Norwegian **Norwegian Long Haul, a defunct subsidiary of Norwegian Air Shuttle, flying long-haul flights * Norwegian Air Lines, a former airline, merged with Scandinavian Airlines in 1951 *Norwegian coupling, used for narrow-gauge railways *Norwegian Cruise Line, a cruise line *Norwegian Elkhound, a canine breed. * Norwegian Forest cat, a domestic feline breed *Norwegian Red, a breed of dairy cattle *Norwegian Township, Pennsylvania, USA Norsk ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gothian Orogeny
The Gothian orogeny () or Kongsberg orogeny was an orogeny in western Fennoscandia that occurred between 1750 and 1500 million years ago. It precedes the younger Sveconorwegian orogeny that has overprinted much of it. The Gothian orogeny formed along a subduction zone and resulted in the formation of calc-alkaline igneous rocks 1700 to 1550 million years ago, including some of the younger members of the Transscandinavian Igneous Belt. The deformation associated with the orogeny can be seen in metatonalite, paragneiss and biotite orthogneisses in southeast Norway. These rocks were all subject to amphibolite facies metamorphism Metamorphism is the transformation of existing Rock (geology), rock (the protolith) to rock with a different mineral composition or Texture (geology), texture. Metamorphism takes place at temperatures in excess of , and often also at elevated .... Footnotes References * * {{Geology of Europe Orogenies of Europe Paleoproterozoic orogenies Meso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleomagnetic Pole
Paleomagnetic poles or paleopoles are positions of the geomagnetic poles identified by the study of magnetic fields of the past as recorded in rocks and sediments. Robert F. Butler, ''PaleomagnetismMagnetic Domains to Geologic Terranes'', 1992Chapter 7: Paleomagnetic poles/ref>Dieke Gerritsen, Bram Vaes, Douwe J. J. van Hinsbergen"Influence of Data Filters on the Position and Precision of Paleomagnetic Poles: What Is the Optimal Sampling Strategy?" Determining paleomagnetic poles Theoretically, paleopoles could be located by measuring paleomagnetism in rocks of similar ages in different parts of the globe. However chronological dating is insufficiently precise for this purpose for remote paleographic eras. In addition, continental drift must be taken into an account. Only approximate locations can be assigned to paleopoles, with varying degree of reliability. Due to changing techniques and data selection and acceptance criteria, many "paleomagnetic poles" reported in the past wo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neoproterozoic
The Neoproterozoic Era is the last of the three geologic eras of the Proterozoic geologic eon, eon, spanning from 1 billion to 538.8 million years ago, and is the last era of the Precambrian "supereon". It is preceded by the Mesoproterozoic era and succeeded by the Paleozoic era of the Phanerozoic eon, and is further subdivided into three geologic period, periods, the Tonian, Cryogenian and Ediacaran. One of the most severe glaciation events known in the geologic record occurred during the Cryogenian period of the Neoproterozoic, when global ice sheets may have reached the equator and created a "Snowball Earth" lasting about 100 million years. The earliest fossils of complex life are found in the Tonian period in the form of ''Otavia'', a primitive sponge, and the earliest fossil evidence of metazoan evolutionary radiation, radiation are found in the Ediacaran period, which included the namesaked Ediacaran biota as well as the oldest definitive cnidarians and bilaterians in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thrust Fault
A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. If the angle of the fault plane is lower (often less than 15 degrees from the horizontal) and the displacement of the overlying block is large (often in the kilometer range) the fault is called an ''overthrust'' or ''overthrust fault''. Erosion can remove part of the overlying block, creating a ''fenster'' (or ''window'') – when the underlying block is exposed only in a relatively small area. When erosion removes most of the overlying block, leaving island-like remnants resting on the lower block, the remnants are called ''klippen'' (singular '' klippe''). Blind thrust faults If the fault plane terminates before it reaches the Earth's surface, it is called a ''blind thrust'' fault. Because of the lack of surface evidence, blind thrust fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
