Physical geology in our overview of the earth, we found out that earths internal heat combined with other mechanisms causes rocks to melt in the asthenosphere and lithosphere. Komatite so rare were not going to talk about it much ultramafic rocks are not common on earths crust, but they make up most of the are found in the mantle mostly olivine and pyroxene green minerals. Petrology of metamorphosed chromitebearing ultramafic rocks from the red lodge district, montana by patricia j. Ultramafic rocks very low silica contain 85% ferromagnesian minerals intrusive. Loferski abstract the chromite deposits near red lodge, mont. Hydration of oceanic peridotites results in increasing serpentine content, which affects lithospheric physical properties and the global biogeochemical cycles of various elements. There has been growing interest in the compositions of hydrated ultramafic rocks and the degree to which these compositions can be used to infer slab fluxes of trace elements at greater depths in subduction zones, including arc source regions see hattori and guillot, 2003. Hydrothermal zones detection using airborne magnetic and gamma ray spectrometric data of maficultramafic rocks at gabal elrubshi area, central eastern desert ced, egypt. Parent material of igneous rocks forms from partial melting of rocks magma at surface is called lava general characteristics of magma general characteristics of magma. An early investigation of the occurrence and mining methods for corundum associated with ultramafic rocks in georgia was performed by king 1894.
The relative abundances of the rareearth elements ree and high field strength elements hfse remain fairly constant throughout the ultramafic series, and the lower. Locations of mafic ultramafic intrusions sampled in this study with major geological subdivisions. This is actually a pretty rare occurrence, and would lead us to believe that mafic and ultramafic rocks should be fairly uncommon. It is a continuation of the authors work published in 2010. They are separated from the ultramafic rocks in northwestern oriente by a major structural and. Lecture notes 3 igneous rocks glendale community college. Early neoproterozoic assembly and subsequent rifting in south.
Classification of maficultramafic intrusions in ontario. These rocks generally contain high amounts of fe and trace metals such as cr and ni alexander et al. Metamorphism of mafic, calcareous and ultramafic rocks youtube. However, in the eastem part of oriente province, the ultramafic rocks are more coherent and cover a much larger area. The reason is that these rocks form as cumulates by segregation of solid crystals from magma, and not by solidification of the magma itself. Processes and ore deposits of ultramaficmafic magmas through space and time focuses on the fundamental processes that control the formation of ore deposits from ultramaficmafic magmas, covering chromite, platinumgroup element pge, nisulfides and tivbearing magnetite. Petrology of metamorphosed chromitebearing ultramafic rocks. For the purposes of this discussion, ultramafic rocks are considered to be a subset of read more. The reason is that these rocks form as cumulates by segregation of solid crystals from magma, and not by solidification of the magma.
This book presents an extensive overview of literature published globally in the last decades on ree distribution in minor and accessory minerals from various types of ultramafic, mafic, and other plutonic rocks. It is important, therefore, to compare the petrology of. Ultramafic definition of ultramafic by the free dictionary. Volcanic rocks and several gabbroic units were sampled from outcrops at the localities indicated in fig. Based on textural criteria, the garnet clinopyroxenites were divided into three types. Processes and ore deposits of ultramaficmafic magmas. The rainy creek complex represents a composite of successive intrusions of igneous rocks emplaced into the precambrian belt series, probably in middle cretaceous time. Use features like bookmarks, note taking and highlighting while reading rare earth elements in ultramafic and mafic rocks and their minerals. Geochemical study of ultramafic volcanic and plutonic rocks. Petrology of the ultramafic and gabbroic rocks of the.
Petrology of the ultramafic and gabbroic rocks of the brady. Processes and ore deposits of ultramafic mafic magmas through space and time focuses on the fundamental processes that control the formation of ore deposits from ultramafic mafic magmas, covering chromite, platinumgroup element pge, nisulfides and tivbearing magnetite. The succession began with the emplacement of a body of coarsegrained biotite pyroxenite with a core of coarsegrained biotitite, which is considered to have formed from the accumulation of alkalies and volatiles near the roof. The ultramafic rocks undergo continuous recrystallization due to largescale convection in the sublithosphere mantle and as a result of tectonic processes in the lithosphere. Understanding the physical properties of ultramafic rocks is important for evaluating a wide variety of petrologic models of the oceanic lithosphere, particularly upper mantle and lower crust. Early neoproterozoic assembly and subsequent rifting in. Hopkins 1914 presented a descriptive listing of asbestos, talc, and soapstone. Introduction mafic and ultramafic rocks were drilled at sites 567, 566, 569, and 570 of leg 84 on the landward slope of. Classification of maficultramafic intrusions in ontario and. Ultramafic rocks are those containing 18 % mgo and minerals.
The succession began with the emplacement of a body of coarsegrained biotite pyroxenite with a core of coarsegrained biotitite, which is considered to have formed from the. Metamorphic evolution of garnetbearing ultramafic rocks. Strict application of the modified classification system requires following the flow chart in fig. Petrology and geochemistry of metamorphosed ultramafic bodies. The bulk of the mantle rocks, therefore, meet the criteria of metamorphic rocks. Pages in category ultramafic rocks the following pages are in this category, out of total. Igneous rock evolution plate tectonics and igneous rock distribution. Ultramafic metamorphic rocks result from the metamorphism of mantle rocks and some oceanic crust and contain dominantly magnesium, silicon, and carbon dioxide, with smaller amounts of iron, calcium, and aluminum. The ultramafic rocks from oceanic regions may possibly be equivalent to the ultramafic rocks of ophiolite complexes e. Metamorphic ultramafic rocks represent the largest volume of rocks of the planet.
Komatite so rare were not going to talk about it much ultramafic rocks are not common on earths crust, but they make up most of the are found in the mantle. Ultramafic rocks are all plutonic rocks, there are no volcanic counterparts, as there are for rocks that are classified in the qapf diagram. Equigranular garnet, porphyroclastic garnet, and megacrystic garnet pyroxenites. Metamorphism of mafic, calcareous and ultramafic rocks content writer. Petrology of metamorphosed chromitebearing ultramafic. Formation, classification, and identification of igneous rocks next. The exploration, exploitation and use of these magmatic ores are important aspects of geology and. Compositional name 0 0 0 0 0 020% 020% 50100% very dark ultramafic.
In contextgeologylangen terms the difference between ultramafic and mafic is that ultramafic is geology describing igneous rocks that contain magnesium and iron and only a very small amount of silica, such as are found in the earths mantle while mafic is geology describing rocks, such as silicate minerals, magmas, and volcanic and intrusive. Our own recent experience with trying to apply the iugs classification scheme to the numerous carbonaterich, melilite free, ultramafic alkaline rocks of west greenland, northern quebec and labrador also highlights the shortcomings of the current scheme. How to classify igneous rocks into ultramafic, mafic. Ultramafic rocks are those containing 18 % mgo and rocks dunites, peridotites and metamorphic rocks talc carbonate and serpentinite. An igneous rock with a very low silica content and rich in minerals such as hypersthene, augite, and olivine. Fragments of ash, crystals, pumice, rocks ultramafic peridotite mafic gabbro basalt scoria volcanic tuff intermediate diorite andesite pumice volcanic tuff felsic granite rhyolite obsidian pumice volcanic tuff if an intrusive igneous rock has extremely large minerals 2 inches. The rizhao hujialin area is located in the central sulu ultrahighpressure orogenic belt, where garnet clinopyroxenite is exposed in the upper part of an ultramafic rock complex and serpentinized dunite is exposed in its lower part. Equigranular garnet, porphyroclastic garnet, and megacrystic garnet. Petrology and geochemistry of metamorphosed ultramafic. Ultramafic rocks in thrust zones of northwestern oriente. The oregon department of geology and mineral industries bulletin 95 north american ophiolites has an index map page v which summarizes the locations of ophiolites in north america. Rocks archean subprovince type plutonic volcanicplutonic metasedimentary highgrade gneiss 500 km studied intrusion 90 o figure 1. The horoman ultramafic rocks are strongly modified by deepseated deformation and recrystallization, and additionally by mylonitization during the upthrusting intrusion into the earths crust.
Ababitibi, erenglish river, opopatica, ququetico, ucuchi, wawawa, wbwabigoon. Because the maximum length of these streams is 90%, fine or coarse grained. Geosciences free fulltext correlation of elastic moduli. Statewide investigations of mafic and ultramafic bodies and their associated minerals are scarce. Rare earth elements in ultramafic and mafic rocks and their. When there are red flags about anything, and in this case plenty of them are associated with the covid19 virus, then i am always going to suspect wrongdoing. Pyroxenitic komatiites olivine less abundant and subcalcic augite more plentiful. Processes and ore deposits of ultramaficmafic magmas through. Our revision to the iugs sequential system is highlighted in bold and the quotation marks refer to sections in le maitre 2002. Metamorphic evolution of garnetbearing ultramafic rocks in. The rainy creek alkalineultramafic igneous complex near. Each of these is introduced simplistically below, and then further explored in other pages of the site. It is important, therefore, to compare the petrology of ultramafic rocks from the midoceanic ridges.
The oregon department of geology and mineral industries bulletin 95 north american ophiolites has an index map page v which summarizes the. Rocks formed from lava are extrusive, or volcanic rocks. Minor and accessory minerals kindle edition by lesnov, felix p download it once and read it on your kindle device, pc, phones or tablets. Hydrothermal zones detection using airborne magnetic and gamma ray spectrometric data of mafic ultramafic rocks at gabal elrubshi area, central eastern desert ced, egypt. Rare earth elements in ultramafic and mafic rocks and their minerals. The mafic rocks of these maficultramafic intrusions are mainly characterized by gabbro and diabase and the ultramafic rocks by the gabbro and diabase, with ophitic texture consisting mainly of plagioclase. These associations suggest a common derivation, but details of the way that carbonatite magmas might concentrate geochemically scarce metals. Contain variable but greater than 10% of both ortho and clinopyroxene, and accessory phases. Apr 28, 2020 when there are red flags about anything, and in this case plenty of them are associated with the covid19 virus, then i am always going to suspect wrongdoing. An introduction to igneous rocks requires exploration of three core ideas. Pgecoppernickel potential of maficultramafic intrusions. The exploration, exploitation and use of these magmatic ores are. Petrology of the ultramafic and gabbroic rocks of the brady glacier nickelcopper deposit, fairweather range, southeastern alaska by glen r.
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