Metamorphic Rocks and the Rock Cycle
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Editorial for Special Issue “Ore Genesis and Metamorphism: Geochemistry, Mineralogy, and Isotopes”
minerals Editorial Editorial for Special Issue “Ore Genesis and Metamorphism: Geochemistry, Mineralogy, and Isotopes” Pavel A. Serov Geological Institute of the Kola Science Centre, Russian Academy of Sciences, 184209 Apatity, Russia; [email protected] Magmatism, ore genesis and metamorphism are commonly associated processes that define fundamental features of the Earth’s crustal evolution from the earliest Precambrian to Phanerozoic. Basically, the need and importance of studying the role of metamorphic processes in formation and transformation of deposits is of great value when discussing the origin of deposits confined to varied geological settings. In synthesis, the signatures imprinted by metamorphic episodes during the evolution largely indicate complicated and multistage patterns of ore-forming processes, as well as the polygenic nature of the mineralization generated by magmatic, postmagmatic, and metamorphic processes. Rapid industrialization and expanding demand for various types of mineral raw ma- terials require increasing rates of mining operations. The current Special Issue is dedicated to the latest achievements in geochemistry, mineralogy, and geochronology of ore and metamorphic complexes, their interrelation, and the potential for further prospecting. The issue contains six practical and theoretical studies that provide for a better understanding of the age and nature of metamorphic and metasomatic transformations, as well as their contribution to mineralization in various geological complexes. The first article, by Jiang et al. [1], reports results of the first mineralogical–geochemical Citation: Serov, P.A. Editorial for studies of gem-quality nephrite from the major Yinggelike deposit (Xinjiang, NW China). Special Issue “Ore Genesis and The authors used a set of advanced analytical techniques, that is, electron probe microanaly- Metamorphism: Geochemistry, sis, X-ray fluorescence (XRF) spectrometry, inductively coupled plasma mass spectrometry Mineralogy, and Isotopes”. -
4.5Making Metamorphic Rock Inferences
4.5 Making Metamorphic rock inferences How do geologists identify metamorphic rocks? Infer the parent rock Metamorphism (to change form) is a process in which a parent rock undergoes changes in the mineralogy, texture, and sometimes modifies the parent rocks chemical composition. Every metamorphic rock forms from a pre-existing rock, be it a metamorphic, igneous, or sedimentary rock, called the parent rock. Every metamorphic rock has a parent rock, called a “Protolith”. Source: Ohio Oil and Gas Energy Education Program 1. Pull out samples 4B, 13B, 17B, 19B, and 22B. These are all possible Protoliths “Parent Rocks” (sedimentary/ Igneous rocks) to a few of your metamorphic samples found in your kits. Keep these out in front of you. 2. Pull out rock samples 23B, 28B, 29B, and 30B. These are all metamorphic rocks that have undergone metamorphism. Lay the rocks out on the table in front of you. 3. Using dilute hydrochloric acid (HCl) or vinegar put a drop on sample 29B; it should effervesce or “fizz”. That means that the Protolith “parent rock” you choose should also effervesce or “fizz”. If it doesn’t then you will need to go back and try again until you find the correct Protolith. 4. Match the metamorphic rock with its Protolith “parent rock” below: Metamorphic 23B 27B 28B 29B 30B rock Protolith “Parent rock” Reflection Name two primary environmental changes a protolith rock must undergo to transition from its protolith to a metamorphic rock. OHIO OIL & GAS ENERGY EDUCATION PROGRAM oogeep.org 4.5 Making metamorphic rock inferences continued Infer the grade Sometimes the protoliths “parent rocks” are a metamorphic rock and that parent rock is metamorphosed into a new metamorphic rock that has experienced a different grade (intensity) of metamorphism. -
Bedrock Geology Glossary from the Roadside Geology of Minnesota, Richard W
Minnesota Bedrock Geology Glossary From the Roadside Geology of Minnesota, Richard W. Ojakangas Sedimentary Rock Types in Minnesota Rocks that formed from the consolidation of loose sediment Conglomerate: A coarse-grained sedimentary rock composed of pebbles, cobbles, or boul- ders set in a fine-grained matrix of silt and sand. Dolostone: A sedimentary rock composed of the mineral dolomite, a calcium magnesium car- bonate. Graywacke: A sedimentary rock made primarily of mud and sand, often deposited by turbidi- ty currents. Iron-formation: A thinly bedded sedimentary rock containing more than 15 percent iron. Limestone: A sedimentary rock composed of calcium carbonate. Mudstone: A sedimentary rock composed of mud. Sandstone: A sedimentary rock made primarily of sand. Shale: A deposit of clay, silt, or mud solidified into more or less a solid rock. Siltstone: A sedimentary rock made primarily of sand. Igneous and Volcanic Rock Types in Minnesota Rocks that solidified from cooling of molten magma Basalt: A black or dark grey volcanic rock that consists mainly of microscopic crystals of pla- gioclase feldspar, pyroxene, and perhaps olivine. Diorite: A plutonic igneous rock intermediate in composition between granite and gabbro. Gabbro: A dark igneous rock consisting mainly of plagioclase and pyroxene in crystals large enough to see with a simple magnifier. Gabbro has the same composition as basalt but contains much larger mineral grains because it cooled at depth over a longer period of time. Granite: An igneous rock composed mostly of orthoclase feldspar and quartz in grains large enough to see without using a magnifier. Most granites also contain mica and amphibole Rhyolite: A felsic (light-colored) volcanic rock, the extrusive equivalent of granite. -
Geology of the Berne Quadrangle Black Hills South Dakota
Geology of the Berne Quadrangle Black Hills South Dakota GEOLOGICAL SURVEY PROFESSIONAL PAPER 297-F Prepared partly on behalf of the U.S. Atomic Energy Commission Geology of the Berne Quadrangle Black Hills South Dakota By JACK A. REDDEN PEGMATITES AND OTHER PRECAMBRIAN ROCKS IN THE SOUTHERN BLACK HILLS GEOLOGICAL SURVEY PROFESSIONAL PAPER 297-F Prepared partly on behalf of the U.S. Atomic Energy Commission UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1968 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY William T. Pecora, Director For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 CONTENTS Page Page Abstract._ _-------------_-___________-_____________ 343 Pegmatites Continued Introduction.______________________________________ 344 Mineralogy __ _____________-___-___-_-------_--- 378 Previous work__________________________________ 345 Origin.- --___-____-_-_-_---------------------_ 380 Fieldwork and acknowledgments._-_-_--__________ 345 Paleozoic and younger rocks. ________________________ 381 Geologic setting____--__-______________________ ____ 345 Deadwood Formation, __________________________ 381 Metamorphic rocks_________________________________ 347 Englewood Formation.. _ __________--____-_-__--_ 381 Stratigraphic units west of Grand Junction fault___- 347 Pahasapa Limestone- _______-_____.__-----_-- - 381 Vanderlehr Formation.._____________________ 347 Quaternary and Recent deposits. _________________ 382 Biotite-plagioclase gneiss.________________ -
Geochemical Cycle
Geochemical cycle In Earth science, a geochemical cycle is the pathway that chemical elements take in the surface and crust of the Earth.[1] The term "geochemical" tells us that geological and chemical factors are all included. The migration of heated and compressed chemical elements and compounds such as silicon, aluminium, and general alkali metals through the means of subduction and volcanism is known in the geological world as geochemical cycles. The geochemical cycle encompasses the natural separation and concentration of elements and heat-assisted recombination processes. Changes may not be apparent over a short term, such as with biogeochemical cycles, but over a long term changes of great magnitude occur, including the evolution of continents and oceans.[1] Contents Differentiating biogeochemical cycles Earth system Pathways Important cycles See also References Differentiating biogeochemical cycles Some may use the terms biogeochemical cycle and geochemical cycle interchangeably because both cycles deal with Earth's reservoirs. However, a biogeochemical cycle refers to the chemical interactions in surface reservoirs such as the atmosphere, hydrosphere, lithosphere, and biosphere whereas a geochemical cycle refers to the chemical interactions that exist in crustal and sub crustal reservoirs such as the deep earth and lithosphere. Earth system The Earth, as a system, is open to radiation from the sun and space, but is practically closed with regard to matter.[2] As all closed systems, it follows the law of conservation of mass which -
Metamorphic Rocks (Lab )
Figure 3.12 Igneous Rocks (Lab ) The RockSedimentary Cycle Rocks (Lab ) Metamorphic Rocks (Lab ) Areas of regional metamorphism Compressive Compressive Stress Stress Products of Regional Metamorphism Products of Contact Metamorphism Foliated texture forms Non-foliated texture forms during compression during static pressure Texture Minerals Other Diagnostic Metamorphic Protolith Features Rock Name Non-foliated calcite, dolomite cleavage faces of Marble Limestone calcite usually visible quartz quartz grains are Quartzite Quartz Sandstone intergrown Foliated clay looks like shale but Slate Shale breaks into layers muscovite, biotite very fine-grained, but Phyllite Shale has a sheen like satin muscovite, biotite, minerals are large Schist Shale may have garnet enough to see easily, muscovite and biotite grains are parallel to each other feldspar, biotite, has layers of different Gneiss Any protolith muscovite, quartz, minerals garnet amphibole layered black Amphibolite Basalt or Andesite amphibole grains Texture Minerals Other Diagnostic Metamorphic Protolith Features Rock Name Non-foliated calcite, dolomite cleavage faces of Marble Limestone calcite usually visible quartz quartz grains are Quartzite Quartz Sandstone intergrown Foliated clay looks like shale but Slate Shale breaks into layers muscovite, biotite very fine-grained, but Phyllite Shale has a sheen like satin muscovite, biotite, minerals are large Schist Shale may have garnet enough to see easily, muscovite and biotite grains are parallel to each other feldspar, biotite, has layers of different Gneiss Any protolith muscovite, quartz, minerals garnet amphibole layered black Amphibolite Basalt or Andesite amphibole grains Identification of Metamorphic Rocks 12 samples 7 are metamorphic 5 are igneous or sedimentary Protoliths and Geologic History For 2 of the metamorphic rocks: Match the metamorphic rock to its protolith (both from Part One) Write a short geologic history of the sample 1. -
Origin, Texture, and Classification of Metamorphic Rocks - Teklewold Ayalew
GEOLOGY – Vol. II - Origin, Texture, and Classification of Metamorphic Rocks - Teklewold Ayalew ORIGIN, TEXTURE, AND CLASSIFICATION OF METAMORPHIC ROCKS Teklewold Ayalew Addis Ababa University, Ethiopia Keywords: aluminosilicates, assemblage, fabric, foliation, gneissose banding, index mineral, isograd, lineation, lithosphere, metamorphic facies, metasomatism, orogenic belt, schistosity Contents 1. Introduction 2. Occurrence 2.1. Orogenic Metamorphism 2.2. Contact Metamorphism 2.3. Ocean Floor Metamorphism 3. Classification 4. Minerals of Metamorphic Rocks 5. Metamorphic Facies 5.1. Facies of Very Low Grade 5.2. Greenschist Facies 5.3. Amphibolite Facies 5.4. Granulite Facies 5.5. Hornblende Hornfels Facies 5.6. Pyroxene Hornfels Facies 5.7. Blueschist Facies 5.8. Eclogite Facies 6. Tectonic Setting of Metamorphic Facies 7. Textures 7.1. Layering, Banding, and Fabric Development 8. Kinetics 8.1. Diffusion 8.2. Nucleation 8.3. Crystal Growth AcknowledgmentUNESCO – EOLSS Glossary Bibliography Biographical SketchSAMPLE CHAPTERS Summary Metamorphic rocks are igneous, sedimentary, or other metamorphic rocks whose texture and composition has been changed by metamorphism. Metamorphism occurs as a response to changes in the physical or chemical environment of any pre-existing rock, such as variations in pressure or temperature, strain, or the infiltration of fluids. It involves recrystallization of existing minerals into new grains and/or the appearance of new mineral phases and breakdown of others. Metamorphic processes take place ©Encyclopedia of Life Support Systems (EOLSS) GEOLOGY – Vol. II - Origin, Texture, and Classification of Metamorphic Rocks - Teklewold Ayalew essentially in the solid state. The rock mass does not normally disaggregate and lose coherence entirely; however small amounts of fluids are frequently present and may play an important catalytic role. -
Earth Systems and Interactions
The Earth System Earth Systems and Interactions Key Concepts • How do Earth systems What do you think? Read the three statements below and decide interact in the carbon whether you agree or disagree with them. Place an A in the Before column cycle? if you agree with the statement or a D if you disagree. After you’ve read • How do Earth systems this lesson, reread the statements to see if you have changed your mind. interact in the phosphorus Before Statement After cycle? 1. The amount of water on Earth remains constant over time. 2. Hydrogen makes up the hydrosphere. 3. Most carbon on Earth is in the atmosphere. 3TUDY#OACH Earth Systems Make a Table Contrast the carbon cycle and the Your body contains many systems. These systems work phosphorus cycle in a two- together and make one big system—your body. Earth is a column table. Label one system, too. Like you, Earth has smaller systems that work column Carbon Cycle and together, or interact, and make the larger Earth system. Four the other column Phosphorus of these smaller systems are the atmosphere, the Cycle. Complete the table hydrosphere, the geosphere, and the biosphere. as you read this lesson. The Atmosphere Reading Check The outermost Earth system is a mixture of gases and 1. Identify What systems particles of matter called the atmosphere. It forms a layer make up the larger Earth around the other Earth systems. The atmosphere is mainly system? nitrogen and oxygen. Gases in the atmosphere move freely, helping transport matter and energy among Earth systems. -
A) Conglomerate B) Dolostone C) Siltstone D) Shale 1. Which
1. Which sedimentary rock would be composed of 7. Which process could lead most directly to the particles ranging in size from 0.0004 centimeter to formation of a sedimentary rock? 0.006 centimeter? A) metamorphism of unmelted material A) conglomerate B) dolostone B) slow solidification of molten material C) siltstone D) shale C) sudden upwelling of lava at a mid-ocean ridge 2. Which sedimentary rock could form as a result of D) precipitation of minerals from evaporating evaporation? water A) conglomerate B) sandstone 8. Base your answer to the following question on the C) shale D) limestone diagram below. 3. Limestone is a sedimentary rock which may form as a result of A) melting B) recrystallization C) metamorphism D) biologic processes 4. The dot below is a true scale drawing of the smallest particle found in a sample of cemented sedimentary rock. Which sedimentary rock is shown in the diagram? What is this sedimentary rock? A) conglomerate B) sandstone C) siltstone D) shale A) conglomerate B) sandstone C) siltstone D) shale 9. Which statement about the formation of a rock is best supported by the rock cycle? 5. Which sequence of events occurs in the formation of a sedimentary rock? A) Magma must be weathered before it can change to metamorphic rock. A) B) Sediment must be compacted and cemented before it can change to sedimentary rock. B) C) Sedimentary rock must melt before it can change to metamorphic rock. C) D) Metamorphic rock must melt before it can change to sedimentary rock. D) 6. Which sedimentary rock formed from the compaction and cementation of fragments of the skeletons and shells of sea organisms? A) shale B) gypsum C) limestone D) conglomerate Base your answers to questions 10 and 11 on the diagram below, which is a geologic cross section of an area where a river has exposed a 300-meter cliff of sedimentary rock layers. -
The Geology of the Tama Kosi and Rolwaling Valley Region, East-Central Nepal
The geology of the Tama Kosi and Rolwaling valley region, East-Central Nepal Kyle P. Larson* Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan, S7N 5E2, Canada ABSTRACT Tama Kosi valley in east-central Nepal (Fig. 1). which were in turn assigned to either the Hima- In order to properly evaluate the evolution of the layan gneiss group or the Midlands metasedi- The Tama Kosi/Rolwaling area of east- Himalaya and understand the processes respon- ment group (Fig. 2). The units of Ishida (1969) central Nepal is underlain by the exhumed sible for its formation, it is critical that all areas and Ishida and Ohta (1973) are quite similar in mid-crustal core of the Himalaya. The geol- along the length of the mountain chain be inves- description to the tectonostratigraphy reported ogy of the area consists of Greater Hima- tigated, at least at a reconnaissance scale. by Schelling (1992) who revisited and expanded layan sequence phyllitic schist, paragneiss, The Tama Kosi valley is situated between the the scope of their early reconnaissance work. and orthogneiss that generally increase in Cho Oyu/Everest/Makalu massifs to the east Schelling (1992) separated the geology of metamorphic grade from biotite ± garnet and the Kathmandu klippe/nappe to the west the lower and middle portion of the Tama Kosi assemblages to sillimanite-grade migmatite (Fig. 1). Recent work in these areas serves to into the more traditional Greater Himalayan up structural section. All metamorphic rocks highlight stark differences between them. In the sequence (Higher Himalayan Crystallines) and are pervasively deformed and commonly Kathmandu region, the extruded midcrustal core Lesser Himalayan sequence lithotectonic assem- record top-to-the-south sense shear. -
Geologic Boulder Map of Campus Has Been Created As an Educational Educational an As Created Been Has Campus of Map Boulder Geologic The
Adam Larsen, Kevin Ansdell and Tim Prokopiuk Tim and Ansdell Kevin Larsen, Adam What is Geology? Igneous Geo-walk ing of marine creatures when the limestone was deposited. It also contains by edited and Written Geology is the study of the Earth, from the highest mountains to the core of The root of “igneous” is from the Latin word ignis meaning fire. Outlined in red, numerous fossils including gastropods, brachiopods, receptaculita and rugose the planet, and has traditionally been divided into physical geology and his- this path takes you across campus looking at these ancient “fire” rocks, some coral. The best example of these are in the Geology Building where the stone torical geology. Physical geology concentrates on the materials that compose of which may have been formed at great depths in the Earth’s crust. Created was hand-picked for its fossil display. Campus of the Earth and the natural processes that take place within the earth to shape by the cooling of magma or lava, they can widely vary in both grain size and Granite is another common building stone used on campus. When compa- its surface. Historical geology focuses on Earth history from its fiery begin- mineral composition. This walk stops at examples showing this variety to help nies sell granite, they do not use the same classification system as geologists. nings to the present. Geology also explores the interactions between the you understand what the change in circumstances will do to the appearance Granite is sold in many different colours and mineral compositions that a Map Boulder Geologic lithosphere (the solid Earth), the atmosphere, the biosphere (plants, animals of the rock. -
MSA PRESIDENTIAL ADDRESS Metamorphism and the Evolution of Subduction on Earth
American Mineralogist, Volume 104, pages 1065–1082, 2019 MSA PRESIDENTIAL ADDRESS Metamorphism and the evolution of subduction on Earth MICHAEL BROWN1,* AND TIM JOHNSON2,3 1Laboratory for Crustal Petrology, Department of Geology, University of Maryland, College Park, Maryland 20742, U.S.A. Orcid 0000-0003-2187-616X 2School of Earth and Planetary Sciences, The Institute for Geoscience Research (TIGeR), Curtin University, GPO Box U1987, Perth, West Australia 6845, Australia. Orcid 0000-0001-8704-4396 3Center for Global Tectonics, State Key Laboratory for Geological Processes and Mineral Resources, China University of Geosciences, Wuhan, Hubei Province, 430074, China ABSTRACT Subduction is a component of plate tectonics, which is widely accepted as having operated in a manner similar to the present-day back through the Phanerozoic Eon. However, whether Earth always had plate tectonics or, if not, when and how a globally linked network of narrow plate boundaries emerged are mat- ters of ongoing debate. Earth’s mantle may have been as much as 200–300 °C warmer in the Mesoarchean compared to the present day, which potentially required an alternative tectonic regime during part or all of the Archean Eon. Here we use a data set of the pressure (P), temperature (T), and age of metamorphic rocks from 564 localities that vary in age from the Paleoarchean to the Cenozoic to evaluate the petrogenesis and secular change of metamorphic rocks associated with subduction and collisional orogenesis at convergent plate boundaries. Based on the thermobaric ratio (T/P), metamorphic rocks are classified into three natural groups: high T/P type (T/P > 775 °C/GPa, mean T/P ~1105 °C/GPa), intermediate T/P type (T/P between 775 and 375 °C/GPa, mean T/P ~575 °C/GPa), and low T/P type (T/P < 375 °C/GPa, mean T/P ~255 °C/GPa).