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Deseado Massif
The Deseado Massif (Spanish: ''Macizo del Deseado'') is a massif in southern Patagonia located in the Argentine province of Santa Cruz. On surface the massif is made up of Middle to Late Jurassic-aged felsic volcanic rocks. Analysis of mantle xenoliths reveals that the lithospheric mantle of the Deseado Massif is about 2100 to 1000 million years old. As such the Deseado Massif is one of the oldest regions of Patagonia as it existed in some form during the Paleo and Mesoproterozoic. In the Neoproterozoic the Deseado Massif together with the Falkland Islands formed part of the supercontinent Rodinia. Since then Deseado Massif has been next to the Falkland Islands. The eastern sector of the Deseado Massif contains a Jurassic caldera with a zircon U–Pb eruption age of 178.7 ± 1.9 million years. Economic geology The Deseado Massif contains valuable epithermal gold deposits. The richness of Deseado Massif in gold may stem from its ancient and enriched mantle lithosphere A mantl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Huincul Fault
The Huincul Fault or Huincul Fault Zone ( es, Falla de Huincul, Zona de falla Huincul) is an east-to-west-oriented, continental-scale fault that extends from the Neuquén Basin eastwards into the Argentine Shelf. To the west, it has been proposed to extend across the Andes to the Chilean Coast Range. In the Neuquén Basin, the fault exhibits a slightly curved path, being convex to the north. It is a major geological discontinuity and it truncates the north-to-south-oriented Pampean orogen, among other structures. Because of this, it has been proposed to represent the northern geological limit of Patagonia. Origin and development The fault develops on the suture zone between the Patagonian terranes and western Gondwana. In a broader sense, the Huincul Fault Zone is a belt of deformation, thus it is the suture zone itself. The first and main deformation phase along the fault zone began in the Toarcian age continued through the Valanginian age before vanishing in Albian time ... [...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 sur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Landforms Of Santa Cruz Province, Argentina
A landform is a natural or anthropogenic land feature on the solid surface of the Earth or other planetary body. Landforms together make up a given terrain, and their arrangement in the landscape is known as topography. Landforms include hills, mountains, canyons, and valleys, as well as shoreline features such as bays, peninsulas, and seas, including submerged features such as mid-ocean ridges, volcanoes, and the great ocean basins. Physical characteristics Landforms are categorized by characteristic physical attributes such as elevation, slope, orientation, stratification, rock exposure and soil type. Gross physical features or landforms include intuitive elements such as berms, mounds, hills, ridges, cliffs, valleys, rivers, peninsulas, volcanoes, and numerous other structural and size-scaled (e.g. ponds vs. lakes, hills vs. mountains) elements including various kinds of inland and oceanic waterbodies and sub-surface features. Mountains, hills, plateaux, and plains are the fou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Manantial Espejo Mine
The Manantial Espejo mine is a large silver mine located in Deseado Massif in Santa Cruz Province, southern Patagonia. Manantial Espejo represents one of the largest silver reserve in Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, t ... and in the world having estimated reserves of 25.7 million oz of silver. See also * Mining in Argentina References Silver mines in Argentina Mines in Santa Cruz Province, Argentina {{SantaCruzAR-geo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cerro Vanguardia Mine
The Cerro Vanguardia Mine is a gold and silver mine located 150 km north west of Puerto San Julián, in the Santa Cruz province of Argentina. It is majority-owned and operated by AngloGold Ashanti AngloGold Ashanti Limited is a global gold mining company. It was formed in 2004 by the merger of AngloGold and the Ashanti Goldfields Corporation. It is now a global gold producer with 21 operations on four continents. The company is listed ..., which holds a 92.5% interest in the min The remaining 7.5% are owned by ''Formicruz'' (''Fomento Minero de Santa Cruz Sociedad del Estado''), a company owned by the province of Santa Cruz.AngloGold Ashanti: Country report Argentina accessed: 14 July 2010 In 2008, the mine contributed 3% to the company's ann ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gold
Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile metal in a pure form. Chemically, gold is a transition metal and a group 11 element. It is one of the least reactive chemical elements and is solid under standard conditions. Gold often occurs in free elemental (native state), as nuggets or grains, in rocks, veins, and alluvial deposits. It occurs in a solid solution series with the native element silver (as electrum), naturally alloyed with other metals like copper and palladium, and mineral inclusions such as within pyrite. Less commonly, it occurs in minerals as gold compounds, often with tellurium ( gold tellurides). Gold is resistant to most acids, though it does dissolve in aqua regia (a mixture of nitric acid and hydrochloric acid), forming a soluble tetrachloroau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epithermal
Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with the assistance of. Roderick McKenzie.'' Oxford: Clarendon Press. and θέρμη, ''heat'' ). Hydrothermal circulation occurs most often in the vicinity of sources of heat within the Earth's crust. In general, this occurs near volcanic activity, but can occur in the shallow to mid crust along deeply penetrating fault irregularities or in the deep crust related to the intrusion of granite, or as the result of orogeny or metamorphism. Seafloor hydrothermal circulation Hydrothermal circulation in the oceans is the passage of the water through mid-oceanic ridge systems. The term includes both the circulation of the well-known, high-temperature vent waters near the ridge crests, and the much-lower-temperature, diffuse flow of water through sedi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uranium–lead Dating
Uranium–lead dating, abbreviated U–Pb dating, is one of the oldest and most refined of the radiometric dating schemes. It can be used to date rocks that formed and crystallised from about 1 million years to over 4.5 billion years ago with routine precisions in the 0.1–1 percent range. The method is usually applied to zircon. This mineral incorporates uranium and thorium atoms into its crystal structure, but strongly rejects lead when forming. As a result, newly-formed zircon deposits will contain no lead, meaning that any lead found in the mineral is radiogenic. Since the exact rate at which uranium decays into lead is known, the current ratio of lead to uranium in a sample of the mineral can be used to reliably determine its age. The method relies on two separate decay chains, the uranium series from 238U to 206Pb, with a half-life of 4.47 billion years and the actinium series from 235U to 207Pb, with a half-life of 710 million years. Decay routes Uranium decays to lead v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zircon
Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of the range of substitution in zircon is (Zr1–y, REEy)(SiO4)1–x(OH)4x–y. Zircon precipitates from silicate melts and has relatively high concentrations of high field strength incompatible elements. For example, hafnium is almost always present in quantities ranging from 1 to 4%. The crystal structure of zircon is tetragonal crystal system. The natural color of zircon varies between colorless, yellow-golden, red, brown, blue, and green. The name derives from the Persian ''zargun'', meaning "gold-hued". This word is corrupted into " jargoon", a term applied to light-colored zircons. The English word "zircon" is derived from ''Zirkon'', which is the German adaptation of this word. Yellow, orange, and red zircon is also known as " hya ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caldera
A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is gone. The ground surface then collapses into the emptied or partially emptied magma chamber, leaving a large depression at the surface (from one to dozens of kilometers in diameter). Although sometimes described as a crater, the feature is actually a type of sinkhole, as it is formed through subsidence and collapse rather than an explosion or impact. Compared to the thousands of volcanic eruptions that occur each century, the formation of a caldera is a rare event, occurring only a few times per century. Only seven caldera-forming collapses are known to have occurred between 1911 and 2016. More recently, a caldera collapse occurred at Kīlauea, Hawaii in 2018. Etymology The term ''caldera'' comes from Spanish ', and Latin ', mean ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precambrian Research
''Precambrian Research'' is a peer-reviewed scientific journal covering the geology of the Earth and its planetary neighbors. It is published by Elsevier and, , the editors-in-chief are V. Pease (Stockholm University) and G.C. Zhao (University of Hong Kong). It was established in 1974. According to the ''Journal Citation Reports'', the journal has a 2013 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a scientometric index calculated by Clarivate that reflects the yearly mean number of citations of articles published in the last two years in a given journal, as ... of 6.023. References External links * * Geology journals Elsevier academic journals English-language journals Publications established in 1974 {{geology-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rodinia
Rodinia (from the Russian родина, ''rodina'', meaning "motherland, birthplace") was a Mesoproterozoic and Neoproterozoic supercontinent that assembled 1.26–0.90 billion years ago and broke up 750–633 million years ago. were probably the first to recognise a Precambrian supercontinent, which they named 'Pangaea I'. It was renamed 'Rodinia' by who also were the first to produce a reconstruction and propose a temporal framework for the supercontinent. Rodinia formed at c. 1.23 Ga by accretion and collision of fragments produced by breakup of an older supercontinent, Columbia, assembled by global-scale 2.0–1.8 Ga collisional events.; Rodinia broke up in the Neoproterozoic with its continental fragments reassembled to form Pannotia 633–573 million years ago. In contrast with Pannotia, little is known yet about the exact configuration and geodynamic history of Rodinia. Paleomagnetic evidence provides some clues to the paleolatitude of individual pieces of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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