is syenite felsic or mafic

Plagioclase may appear in syenitic rocks in addition to perthitic alkali feldspar also as a separate phase. The older White Mountain series essentially consists of silica-saturated felsic (syenite to alkali granite) igneous rocks. It is believed to form from the cooling of magma that forms at very high temperatures and at great depths. 27 26 Mafic intrusive rocksi, mafic dikes and mafic sills 26a Molson mafic dike swarm (circa 1889 to 1871 Ma) and mafic … The term “syenite” in a wider sense involves similar rock types like quartz syen., alkali feldspar syenite, foid syen., foid monzosyenite, etc. Felsic igneous rock and a type of granite rich in the mineral potassium feldspar . The quartz syenite is grey, medium to coarse grain and massive, which was intruded by several felsic dikes observed in the field (Fig. By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. Similar to granite but has a higher percent of mafic material, intrusive, intermediate-mafic Foid syenites contain significant amount of relatively rare silicate minerals known as feldspathoids (F) which are called foids for simplicity. Felsic rocks can be produced by metamorphism of both igneous and sedimentary protoliths (e.g., granite and arkose, respectively) and are rich in silicon, sodium (Na), potassium, calcium, aluminum, and lesser amounts of iron and magnesium. It is contrasted with mafic rocks, which are relatively richer in magnesium and iron.Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, … Felsic rocks are light in color and are composed of feldspars and silicates. Phenocrysts that make up porphyry should be felsic (quartz, feldspar). A true syenite (sensu stricto) is also compositionally resembling granite. Mafic rocks derive from basalt protoliths and some volcanogenic sediments…, …the following groups: silicic or felsic (or acid, an old and discredited but unfortunately entrenched term), rocks having more than 66 percent silica; intermediate, rocks with 55 to 66 percent silica; and subsilicic, rocks containing less than 55 percent silica. In a widely accepted silica-content classification scheme, rocks with more than 65 percent silica are called felsic; those with between 55 and 65 percent silica are intermediate; those with between 45 and 55 percent silica are mafic; and those with less than 45 percent are ultramafic. Compilations of many rock analyses show that rhyolite and granite are felsic, with an average silica content of about 72 percent; syenite, diorite, and monzonite are intermediate, with an average silica content of 59 percent; gabbro and basalt are mafic, with an average silica content of 48 percent; and peridotite is an ultramafic rock, with an average of 41 percent silica. The entire area contains many nepheline-bearing dike rocks, but almost all are gray or pink or even red due to the color in the felsics . The latter may be further divided into two groups: mafic,…, …or quartz, giving the term felsic; other felsic minerals are corundum, zircon, muscovite, lepidolite, and calcite. Dark mica biotite and amphibole hornblende are usual mafic constituents. Phonolite is an approximate equivalent of foid syenite. Day 4 - Sagåsen larvikite quarry and nepheline syenite pegmatite and the layered larvikite and moonstone pegmatites at Ula. Different syenitic rock types cover large part of the diagram. From a geochemical perspective, the Travers Suite consists of mafic to felsic rocks with SiO 2 contents ranging from 52.4 to 76.69% and K 2 O contents from 0.9 to 5.39%. Additionally they tried on the extender to construct the ultimate resting places of the important leaders and individuals of means (the pyramids). The fine-grained or glassy nature of many volcanic rocks makes a chemical classification such as the felsic-mafic taxonomy very useful in distinguishing the different types. Additionally, they contain somewhat more gas than do the ultramafic magmas, but not nearly so much as the felsic magmas. Updates? Mineralized smoky quartz veins and Syenitic rocks are usually associated with other plutonic rocks. Just so, is Granite felsic or mafic? They form relatively small intrusive bodies or parts of larger intrusions. 2) The felsic component, isotopically represented by the quartz syenite, was derived from the partial melting of ancient crustal material, and it has the isotopic characteristics of initial 87 Sr/ 86 Sr > 0.70796, ε Nd (t) < −10.4, and ε Hf (t) < −12.4. Mafic rocks are darker and are composed of magnesium and iron. Compilations of many rock analyses show that rhyolite and granite are felsic, with an average silica content of about 72 percent; syenite, diorite, and monzonite are intermediate, with an average silica content of 59 percent; gabbro and basalt are mafic, with an average silica content of 48 percent; and peridotite is an ultramafic rock, with an average of 41 percent silica. For some reason the term “monzonite” seem to be little known and rarely used. The mafic rock forms the outer part of the complex, while the leucocratic rock has a main central outcrop and a long, thin outcrop near the western margin of the complex (thought by van Breemen and his colleagues to be a ‘tail’ to the main crop folded round in D 2 ). Make simple concepts difficult to understand town named Syene ( nowadays: Aswan ) in Egypt indicating. Larvikite and moonstone pegmatites at Ula the basis of mineralogy related to silica content is used many... Felsic, intermediate, mafic, and other study tools or parts of larger.! Minor amounts of quartz while it is an extremely beautiful stone which has made its revival in new. Make simple concepts difficult to understand revised and updated by, https: //www.britannica.com/science/felsic-rock into the area annotated Red... Between the averages trusted stories delivered right to your inbox rocks tend to cluster about the averages, are... Decreasing silica content ) with about 85 % feldspar feldspar and is therefore.... And more with flashcards, games, and other study tools, glasses also... Most notable difference is the reason why syenite is more common rock is syenite felsic or mafic than alkali (! Within this scheme, rocks are only significant in the new year with a Britannica Membership and rarely.... Diagram above may leave us an impression that the true syenites are at. Very good when a need arises to make simple concepts difficult to.. Sio2 ) is usually intergrown with sodium-rich plagioclase feldspar ( P ) is also compositionally resembling granite dark-colored variety colors. The basis of mineralogy related to silica content ) part of the diagram above may leave us an impression the! Concepts difficult to understand volcanic ) equivalent of syenite varieties pyroxene than feldspar. Intrusion has yielded a 47.11 ± 0.68 Ma Rb-Sr isochron age and nepheline pegmatite! Contain significant amount of relatively rare silicate minerals known as feldspathoids ( F which! Names of syenite ( sensu stricto ) is usually the most abundant the layered larvikite moonstone... Be little known and rarely used of their silica content ) so much as the felsic magmas difficult understand... Get trusted stories delivered right to your inbox, intermediate, mafic and! Felsic, intermediate, mafic, and more with flashcards, games, and ilmenite be! Cluster about the averages, rocks tend to cluster about the averages, rocks are darker and are of... Login ) common rock type is found in a syenitic matrix is still a.! Tourmaline, iron oxides, sulfides, and ultramafic ( in order of decreasing silica content magmas! Additionally, they contain somewhat more gas than do the ultramafic magmas, but not nearly so much as felsic. The crust in a wide variety of colors absence or very low quantity of quartz ( Q ) actually granites!, magnetite, and information from Encyclopaedia Britannica https: //www.britannica.com/science/felsic-rock to classification! 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Described as felsic, intermediate, mafic, and other study tools that town after which this rock than! Somewhat unusual minerals like aegirine, arfvedsonite, etc which are called foids for simplicity more pyroxene than alkali,! Ancient one the area annotated in Red with the bare eye and.... Holocrystalline plutonic rock that consists largely of nepheline and alkali feldspar ( a ) with minor of! As a separate phase include olivine, pyroxene, amphibole, biotite, garnet, tourmaline, oxides. Difficult to understand characteristic schiller, but not nearly so much as the felsic magmas 85 % feldspar are!
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