This study examines how the chemical composition of ultramafic and mafic rocks effects their physicomechanical properties and therefore how influences the. Pdf metamorphism and deformation of mafic and felsic rocks. A mixture of minerals implies the presence of more than one mineral grain, but not necessarily more than one type of mineral. Solid solutions and exchange vectors some minerals e. Free petrology books download ebooks online textbooks tutorials. Igneous rocks and processes, a practical guide by r gill includes bibliographical references p. Thermal properties of rocks usgs publications repository. The rock types of the metamorphosed ultramafic rocks are usually monomineralic and include serpentintes a massive to schistose rock with abundant serpentine minerals. Mafic igneous rocks 1 are classified by geologists using various schemes. Mafic rock or basaltic rock is composed of predominantly mafic minerals although there will be some felsic minerals in it felsic mineral is a light colored silicate mineral where na, k and ca dominate felsic rock or granitic rock is composed of predominantly felsic minerals although there will be some mafic minerals in it.
Pdf mafic and ultramafic rocks, and platinum mineralisation. Many lenses have an entirely ultramafic composition but several at least six are composite, displaying two or more rock types. For example, quartz and feldspars are minerals, but when formed together, they. Most of the precambrian rocks in the black hills predate the wyomingsuperior collision, and while most of the now metamorphosed sedimentary rocks and archean granites have been welldocumented gosselin et al.
Feb 16, 2021 it is widely accepted that the continental lower crust is composed of mafic rocks 1, as generally observed globally in the thick crust of orogens, shields, and platforms 2,3,4,5,6,7,8. Petrogenesis of mafic to felsic plutonic rock associations oxford. Temperature effect on thermal conductivity of mafic rocks. Chapter 4 magmas, igneous rocks, and intrusive activity. Naldrett aj, cabri lj 1976 ultramafic and related mafic rocks. No mafic layer in 80 km thick tibetan crust nature. Silica saturation is a classification of minerals and rocks asoversaturated, saturated, or undersaturated with respect to silica. In recent years numerous studies of altered mafic volcanic rocks have shown that most, if not all, elements can be added or subtracted from a rock during lowtemperature metamorphism metasomatism. Rare earth elements in ultramafic and mafic rocks and. Fluorine in igneous rocks and minerals with emphasis on ultrapotassic mafic and ultramafic magmas and their mantle source regions volume 60 issue 399 skip to main content accessibility help we use cookies to distinguish you from other users and to provide you with a better experience on our websites. The ultramafic rocks undergo continuous recrystallization due to largescale convection in the sublithosphere mantle and as a result of tectonic processes in the lithosphere.
At kohikalawur, along the southeast foot of kohe saymahmude ghazi east of the logar river, seven chromite lenses as much as 4. The presence of highly ni depleted olivine, whole rock cuzr ratios below 1, and the local occurrence of. Highly heterogeneous late mesozoic lithospheric mantle. Rare earth elements in hypabyssal and subvolcanic rocks high in magnesium composition. Pdf petrology and geochemistry of the mafic dyke rocks from. C1 rocks and magmas a rock is defined as a consolidated mixture of minerals. Maficultramafic igneous rocks and associated carbonatites of. Relative abundance of oxygen to cations in igneous and crustal rocks 1.
Contributions of the lower crust to mesozoic mantlederived mafic rocks from the north china craton. The mafic and ultramafic rocks and related dikes of the gem park complex discordantly intrude gneies, amphibolite, and other metamorphic rocks of precam brian age. A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. The bulk of the mantle rocks, therefore, meet the criteria of metamorphic rocks. Geochemistry and geochronology of ophiolitic rocks from. Pdf intrusive rocks in the longwood range represent a component of the permian. This book gives an overview of the worlds literature on analytical data and theoretical concepts of the regularities of rare earth elements ree in ultramafic and mafic rocks of different chemical and mineral compositions mantle restites including those composing mantle xenoliths in alkali basaltoids, highly magnesium hypabyssal rocks, plutonic rocks of mafic. The mafic rocks associated with hornblende gabbro and pyroxenite, retain magmatic structures and show evidence of major change in grain size and shapes granofelses of. Garnet quartzite garnetite and garnitiferous altered mafic rock. Mafic and ultramafic rocks, and platinum mineralisation potential, in the longwood range, southland, new zealand. Metamorphism of mafic rocks l clinopyroxene breaks down to a number of mafic minerals, depending on grade.
Abstract mafic rocks are widespread on the liaodong peninsula and adjacent regions of the north china craton. Rare earth elements in ultramafic and mafic rocks and their minerals. First determine composition, which is based on mineral content or color, if you cant see minerals. And now, its connected to the adobe document cloud. Mafic igneous rocks mafic minerals are usually dark in colour with high sg 3. Minerals free fulltext the effect of chemical composition of. The intermediate to ultramafic rocks contain variable amounts of plagioclase, hornblende and biotite, with minor quartz and rare kfeldspar in the diorites. To identify name igneous rocks, you determine two things about the rock. The eastern alignment, located near the serbomacedonian massif in the vardar zone. You may find ebook pdf rare earth elements in ultramafic and mafic rocks and their minerals minor and accessory minerals document other than just manuals. The role of magma mixing in generating granodioritic. Petrographic characteristics of the mafic and ultramafic rocks suggest crystallization at 7. Mafic and ultramafic rocks associated with granites in the.
Mafic dykes exhibit fine grained margin and medium to coarse grained core, melanocratic, low to. We note that all the investigated zircon grains are free of visible mineral inclusions. Check our section of free ebooks and guides on petrology now. Choose from 29 different sets of mafic rocks flashcards on quizlet. A rock can be composed of only one type of mineral.
However, most minerals are solid solutions that undergo compositional. Adobe acrobat reader dc software is the free global standard for reliably viewing, printing, and commenting on pdf documents. Our site has the following ebook pdf rare earth elements in ultramafic and mafic rocks and their minerals minor and accessory minerals available for free pdf download. Tio2 diagram of pearce 1984, also support supra subduction zone and mid oceanic ridge setting for the mafic and ultramafic suites fig. Mafic rocks have between 45 and 55% of silica, whereas felsic rocks have over 65% of silica, the highest of all types. The rock cycleminerals form rocks all rocks can be transformed into other rock types rocks are divided into 3 categories. Geochemical characteristics of mafic and ultramafic rocks. Jul 01, 2018 overall, the samples from the four plutons are dominated by subalkaline gabbros and gabbroic diorites and belong to the calcalkaline series.
Common mafic rocks include basalt, diabase and gabbro. The rodberget ultramafic mafic complex consists of tectonic lenses of mainly ultramafic mafic rocks dis persed over a distance of ca. Mafic and ultramafic rocks were drilled at sites 567, 566, 569, and 570 of leg 84 on the landward slope of the middle america trench off guatemala. The term is a portmanteau, made up from magnesium and ferric mafic minerals are usually dark in color and have a specific gravity greater than 3. Mineralogic contents felsic rock, with predominance of quartz, alkali feldspar andor feldspathoids. Fluorine in igneous rocks and minerals with emphasis on. Metamorphic facies and metamorphosed mafic rocks v. Geology and geochemistry of maficultramafic rocks koli in. Mafic is an adjective describing a silicate mineral or igneous rock which is rich in magnesium and iron. Mafic rocks include basalt, its intrusive equivalent of gabbro, and a variety of less common rock types with higher or lower. The diorites are medium grained and euhedral to subhedral granular. Granitoid rocks, metamorphic facies and mafic rocks, thermodynamics and geothermobarometry, metamorphic fluids, mass transfer and. Includes the monument dike swarm of northwestern grant county or061, the chief joseph dike swarm.
Examine the safety equipment and preparations needed to scale steep rock walls. Range of spinel compositions in terrestrial mafic and. Ore deposits of mafic igneous rocks geology papers. The simplified stratigraphic columns of figure 1 show the general lithostratigraphy of the drill holes and the main results. Refers to individual minerals or to rocks dominated by them pyroxene amphibole. A plagioclase free mafic rock mainly composed of omphacite and garnet, both of which are modally adundant. The majority of this magmatism was originally thought to have occurred during the pre. Geological society, london, special publications, vol. Goldschmidt 1911, 1912a, contact metamorphosed pelitic, calcareous, and psammitic hornfelses in. Metamorphic ultramafic rocks represent the largest volume of rocks of the planet. Due to the color of the minerals forming them, the rocks.
Download free adobe acrobat reader dc software for your windows, mac os and android devices to view, print, and comment on pdf documents. Talc fels talc schist talc rich foliatednonfoliated rocks ophicalcites serpentine carbonate calcite. This implies that the mafic rocks formed in mid oceanic ridge mor to supra subduction zone ssz tectonic settings. Mafic rocks are low in silica but rich in iron andcontinue reading rocks and rock cycle webquest. Metamorphic facies and metamorphosed mafic rocks chapter 25.
Learn mafic rocks with free interactive flashcards. How to classify igneous rocks into ultramafic, mafic. Some intrusions are rootless and are invasive into sedimentary sequences. Therefore, rocks are divided into ultramafic, mafic, intermediate, and felsic. Gabbro is the name given to intrusive mafic rocks, whereas basalt is the name given to extrusive mafic rocks. For similar determinations, glasses can also be prepared in the laboratory from crystalline rocks. Mafic rocks often also contain calciumrich varieties of plagioclase. Mafic ultramafic igneous rocks and carbonatites of gem park complex, colorado 10530 10525 gem mountain volcanic tuff and flows mostly rhyolite mafic and ultramafic rocks of gem porfc complex in gem pork of mcclure mountain complex at iron mountain nepheline syenite, syenite, and mafic nepheline bearing rocks of the. Reserves were estimated in 1950 to be 840 t assaying 42.
Mafic rocks read chapter 4 of an introduction to metamorphic petrology by bruce yardley or chapter 25 of igneous and metamorphic petrology by john winter or chapter 16 of igneous and metamorphic petrology by philpotts. One of the several schemes based on chemical composition divides igneous rocks into four categories according to silica silicon dioxide, sio2 content. Rocks in the area of turkey heaven mountain in cleburne and randolph counties that are here assigned to the poe bridge mountain group also have been interpreted as part of the wedowee group. Mafic igneous rocks mafic minerals are usually dark in colour with high sg 3 felsic igneous rocks felsic minerals are lighter. This category has the following 2 subcategories, out of 2 total.
Mafic simple english wikipedia, the free encyclopedia. Dikes, plugs, and sills of basalt, diabase, gabbro, and lesser andesite that fed many of the miocene basalt and andesite flows in units tc and tba. Introduction mafic and ultramafic rocks were drilled at sites 567, 566, 569, and 570 of leg 84 on the landward slope of. Mafic rock, in geology, igneous rock that is dominated by the silicates pyroxene, amphibole, olivine, and mica.
Several ophiolitic alignments have been classically recognised in the dinarides and the hellenides fig. Felsic rocks are commonly oversaturated and contain free quartz sio 2, intermediate rocks contain little or no quartz or feldspathoids undersaturated minerals, and mafic rocks may contain abundant feldspathoids. Most mafic minerals are dark in color, and common rock forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Petrology and geochemistry of maficultramafic fragments. Mafic rocks protolith most commonly mafic to intermediate composition igneous rocks moderate al, high fe, mg and ca will not see al 2sio 5 polymorphs or staurolite will see more amphiboles and cpx most metamorphic facies names come from mafic bulk composition metamorphosed rocks at low metamorphic grade, igneous. Maficultramafic igneous rocks and associated carbonatites. Due to the color of the minerals forming them, the rocks are either light or dark. Geochemical characteristics of mafic and felsic igneous rocks 1. However, compared with the ra mafic rocks, the mafic rocks from the af show higher lile, th, u and lree contents and more strongly fractionated ree patterns. Common rock forming mafic minerals include olivine, pyroxene, amphibole, biotite and other micas, augite and the calciumrich plagioclase. Igneous hypabyssal mafic hypabyssal hypabyssalbasalticandesite stock or pipe comments gabbro dikes, sills, and at least one plug intrude steens basalt in northern pueblo mountains and are substantial in size, but too small to appear on state geologic map or252. Mafic dykes of almora region intrude the precambrian crystalline rocks of kumaun lesser himalaya. Bayleys 1928 report on the tate quadrangle assigned all mafic rocks near marble hill to the roan gneiss, which according to bayley 1928 was an allencompassing unit introduced by keith 1907 to include. Kimberlites are product of continental interpolate magmatism and confined to regions underlain by old cratons economic kimberlites occur only on archon cratons primary deposit.
For an isotropic solid, there are two types of body or free. Ppt lecture twelve metamorphism of ultramafic rocks. This means that mafic rocks have fewer minerals than pelitic rocks a given mineral in a mafic rock is stable over a broad pt range by virtue of its ability to shift composition in response to changes in p and t. Metamorphic assemblages found in mafic rocks are used to define the intensity of metamorphism in the metamorphic facies concept chap. Mafic rocks are produced in a variety of plate tectonic settings divergent plate boundaries such as midocean ridges, continental rifts such as our own basin and range province in arizona, and mantle hot spots like hawaii. Metamorphism of mafic rocks the enclave alignment is a magmatic. Then determine the texture of the rock and based on the two, identify t he rock name. Acrossarc geochemical and srndhf isotopic variations of. Figure 2 mafic rockthe influence of silica content on the particular minerals that crystallize from a rock magma is a complex interaction of several parameters, and it cannot be assumed that rocks. It is a fact of the universe that the minerals in mafic rocks tend to have broad ranges in solid solution. Pdf metamorphism and deformation of mafic and felsic. In any case, the first ophiolites to have been recovered from the slope of an active margin are those of the drilled mafic and ultramafic rocks of leg 84. Even such immobile elements as zr and nb can be affected under appropriate conditions e. Mafic rocks often also contain calciumrich varieties of plagioclase feldspar.
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