Lightgray, fine to coarsegrained, foliated, layered muscovitiebearing quartzofeldspathic gneiss. Quartzofeldspathic gneiss forms by metamorphosis of either silicic igneous rocks such as granite, rhyolite, and rhyolitic tuff or silicic sedimentary rocks such as sandstone. Many rocks were injected by a granitoid that has blue quartz and augen of potassic feldspar and are arteritic migmatites. The mineralogy of a particular gneiss is a result of the complex interaction of original rock composition, pressure and temperature of metamorphism, and the addition or loss of components. This page provides mineralogical data about quartzofeldspathic gneiss. The common mineral components are quartz, feldspar, micas, and silicates. A glimpse at the buried archean craton of the transhudson orogen article pdf available in canadian journal of earth sciences 362. Then you can start reading kindle books on your smartphone, tablet, or computer.
The bedrock geology of the naugatuck quadrangle with map. The rocks that form gneiss are exposed to extreme pressures and temperatures of between 600 and 700 degrees celsius. Most gneiss has very a similar composition to granite. Gneiss pronounced nice is a metamorphic rock consisting mostly of quartz and feldspar and showing distinct layering or banding. Pdf field geology of highgrade gneiss terrains researchgate. Geochemistry of quartzofeldspathic gneisses and metamorphic. Oneill and others 1996 mapped this unit and termed it xaq. Ramana kk mishra central soil and materials research station central soil and materials research station r. Such orientations can be interpreted in terms of the stresses that prevailed during the formation of the rock. Definition of quartzofeldspathic in the dictionary. Paragneiss is gneiss derived from sedimentary rock. Quartzofeldspathic gneiss mineral data, information about quartzofeldspathic gneiss, its properties and worldwide locations. Mineral and rock compositions of mafic enclaves in the morton.
The mediumgrained biotitehornblende bearing quartzofeldspathic gneiss is oldest country. Jul 14, 2014 the only catch is that gneiss is a rock and rocks are mixtures of minerals. Streckheisen 1976 diagrams reveal that 60 gneisses sampled from 3 transects across structural grain are granitic in composition. The outer core of the hgd, the xaqf unit, consists of quartzofeldspathic gneiss that is similar to. These temperatures cause the individual minerals to migrate, forming distinct bands through the rock. The mafic gneisses are between the amphibolites and the granitic gneiss in composition and consist of hornblende, biotite, plagioclase, and quartz. Comparative geochemistry of migmatized, interlayered. The dillon quartzofeldspathic gneiss dqg is a thick sequence of conformable microclinerich gneisses that occupy intermediate stratigraphic levels within the exposed section. Biotite gneiss consists of two main types that regionally occur in near equal abundance. Sterling igneous suite alaskite gneiss pale pink, orange, or gray, fine to mediumgrained granite gneiss, rarely with porphyroclasts of microclineorthoclase.
A majority of researchers believe granitegneisses to be granites that have crystallized deep in the earths crust either during the cooling of the magmatic melt under directed pressure or during the process of the magmas movement, as a result of which. Protolith and tectonic setting of an archean quartzofeldspathic. Gneiss is said to be a german word meaning sparkling or bright. The parker phlogopite mine, located near notredamedulaus, quebec, 74 km north of ottawa, is well known among mineral collectors for its centimetric euhedral crystals of black spinel. The lighter bands contain mostly quartz and feldspar, the darker often contain biotite, hornblende, garnet or graphite. Information and translations of quartzofeldspathic in the most comprehensive dictionary definitions resource on the web. Petrography of the biotitehornblende bearing quartzofeldspathic. Minerals free fulltext constraints from geochemistry and. Essential minerals these are minerals that are required within the classification of this rock. Mineral and rock compositions of mafic enclaves in the morton gneiss, selected studies of archean gneisses and lower proterozoic rocks, southern canadian shield, g.
The bands that form on gneiss rock are due to the various rocks that are a part of its makeup. Granitegneiss article about granitegneiss by the free. For example, the outcrop is dominantly quartzofeldspathic gneiss or quartzofeldspathic gneiss crops out throughout the region. The protolith of this rock was a quartzofeldspathic granite which underwent from gly 205 at university of north carolina, wilmington. Gneiss rock varies in groups which make their texture different too, like igneous rocks and the sedimentary metamorphosed rocks which fall into various categories like including the quartzofeldspathic, politics and hornblende gneiss.
Start studying metamorphism, mineral assemblege, and metamorphic rocks. Minerals free fulltext a silicocarbonatitic melt and. A gneiss predominantly composed of quartz and feldspar. Gneiss is the principal rock over extensive metamorphic terrains.
Deformability characteristics of garnetiferous quartzo. Gneiss forms from volcanic rock, shale, or granitic. Minerals have specific chemical comppositions, that is, minerals are compounds, but rocks are mixtures of two or more minerals and have variable compositions. Quartzofeldspathic gneiss bobyarchick and others, 1981. If the wider sense is meant the qualifier is given. Gneiss has been defined as a foliated rock formed by regional metamorphism in which granulose bands or lenticles of granular minerals alternate with schistose bands and lenticles of flaky or elongate prismatic minerals. Gneiss forming from sedimentary rock is called paragneiss and can form from shale, sandstone or basalt while gneiss forming from igneous rock is called orthogneiss and typically forms from granite, gabbro, or diorite. Gneiss is a foliated metamorphic rock identified by its bands and lenses of varying composition, while other bands contain granular minerals with an interlocking texture. It is characterized by alternating light and dark bands differing in mineral composition coarser grained than schist. Allan kays geology department, university of oregon, eugene, or. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Metamorphism, mineral assemblege, and metamorphic rocks.
Plagioclase forms subidioblastic and tabular grains composition determined from maximum. Deformability characteristics of garnetiferous quartzo feldspathic gneiss rock mass a case study hari dev d. Orthogneiss is gneiss derived from igneous rock such as granite. Progressive or prograde metamorphism occurs as the temperature and pressure are increased on the rock. The layering of a gneiss may be weak or welldeveloped and consists of varying concentrations of biotite, garnet, hornblende, mica, and other minerals. Petrologic evolution of gneissic xenoliths in the voiseys bay. Gneiss is a highgrade, metamorphic rock that forms as a result of regional metamorphism. It is this banded appearance and texture rather than composition that define a gneiss. Quartzofeldspathic gneisses and metamorphic mafic rocks are the dominant lithologies in the indian creek and ponymiddle mountain. Then you can start reading kindle books on your smartphone, tablet, or computer no kindle device required. Other bands contain platy or elongate minerals with evidence of preferred orientation. The quartzofeldspathic gneiss is formed by the either silicic igneous metamorphosis or rocks such as granite. The quartzofeldspathic paragneiss that hosts kornerupine at both locations is mapped as biotitequartzfeldspar gneiss referred to here as biotite gneiss or kornerupinebearing biotite gneiss, a unit that is both widespread and abundant in the highlands.
Sarwade central soil and materials research station central soil and materials research station g. The protolith of this rock was a quartzofeldspathic granite. The only catch is that gneiss is a rock and rocks are mixtures of minerals. Sutherland2 1 department of geology and mineralogy, the university of adelaide, adelaide, south australia 2 department of geology, the university, leicester, england. Gneiss is a very widespread rock type, especially in the lower parts of the continental crust, but it is also a common rock on the surface in some places scandinavia, canada, and other shield areas where crystalline rocks are not covered by a layer of sedimentary rocks. As the pressure and temperature increase, a rock of a given chemical composition is expected to undergo a continuous series of chemical reactions between its constituent minerals and any fluid phase present to produce a series of new mineral assemblages. Gneiss rock is further characterized by its alternating light and dark bands of minerals. It is formed by the metamorphosis of granite, or sedimentary rock. Gneiss granofels and migmatite gneiss and granofels range in composition from felsic to intermediate to mafic. Although many gneisses are quartzofeldspathic, the mineral composition is not an. But, as everywhere generally used when no qualifier is prefixed, common gneiss, which is composed of quartz, feldspar and mica, as stated above, is understood, and the term is so employed in this book. Question 15 4 out of 4 points this is a photograph of slickensides along the waterfall canyon trail in the white tanks regional park, just a few miles west of glendale, az. Precambrian geology and bedded iron deposits of the. Gneiss is formed by high temperature and highpressure metamorphic processes acting on formations composed of igneous or sedimentary rocks.
The regional metamorphic assemblages of the quartzofeldspathic gneisses consist of plagioclase. Gneisses of the archean nain province range in composition from quartzofeldspathic to mafic. The darker object to the right of the notebook is amphibolite. It does not matter by what process you metamorphose quartz sandstone and limestone, their composition does not change, and they produce the same kind of metamorphic rock. The proterozoic y terrane of the reading prong of eastern pennsylvania and new jersey consists of lightcolored, sodicrich rocks containing intercalated amphibolite, the losee metamorphic suite, calcarerous and quartzofeldspathic metasedimentary rocks, the intrusive hexenkopf complex, the byram intrusive suite, and quartzpoor monzonite, syenite, and related pyroxene granite. Bancroft corridor in the central metasedimentary belt of the grenville province, the parker mine is exceptional because. Quartzofeldspathic gneiss containing eyeshaped feldspar crystals is termed augen gneiss after the german augen eyes. Choose from 10 different sets of gneiss flashcards on quizlet. Paragneiss is gneiss derived from sedimentary rock such as sandstone. Egypt including humes book and geology of egypt books of rushdi said that were. Precambrian research, 3 1976 433462 433 o elsevier scientific publishing company, amsterdam printed in the netherlands comparative geochemistry of migmatized, interlayered quartzofeldspathic and pelitic gneisses. These igneous suites may represent nearshore phases of the major offshore ophiolite accumulations, and the presence of micaceous quartzofeldspathic sandstones is similar to lithologic associations in some parts of the matakaoa volcanics at east cape pirajno 1980. The gneiss family of rocks varieties, uses and mineral make up. Gneiss displays distinct foliation, representing alternating layers composed of different minerals.
Contains a wide variety of rock types including graphitic schist and marble. Gneisses of dacitic to rhyolitic composition 6976 weight percent sio2. Rocks with a more complex chemical composition, such as shale the mineral clay, however, undergo many compositional, and textural changes. Composition is granite with generally less than 3% dark minerals. Enter your mobile number or email address below and well send you a link to download the free kindle app. The three terms schist, gneiss, and granofels are defined in table 2. We studied gneiss away from and adjacent to dykes and quartzofeldspathic xenoliths in dykes. Gneiss is a high grade metamorphic rock, meaning that it has been subjected to higher temperatures and pressures than schist. Use late, middle, early for volcanic rocks and times. Gneiss can be classified on the basis of minerals that are present, process of formation, chemical composition, or probable parent material. The mineralogy of quartzofeldspathic rocks is generally monotonous. Petrography and traceelement geochemistry of the dillon. Therefore, the best you can do is to report the chemical composition of the minerals found in the gneiss. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext.
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