A-type granites: geochemical characteristics, discrimination and petrogenesis
TL;DR: A-type granites as mentioned in this paper were found to have high SiO2, Na2O+K2O, Fe/Mg, Ga/Al, Zr, Nb, Ga, Y and Ce, and low CaO and Sr.
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Abstract: New analyses of 131 samples of A-type (alkaline or anorogenic) granites substantiate previously recognized chemical features, namely high SiO2, Na2O+K2O, Fe/Mg, Ga/Al, Zr, Nb, Ga, Y and Ce, and low CaO and Sr. Good discrimination can be obtained between A-type granites and most orogenic granites (M-, I and S-types) on plots employing Ga/Al, various major element ratios and Y, Ce, Nb and Zr. These discrimination diagrams are thought to be relatively insensitive to moderate degrees of alteration. A-type granites generally do not exhibit evidence of being strongly differentiated, and within individual suites can show a transition from strongly alkaline varieties toward subalkaline compositions. Highly fractionated, felsic I- and S-type granites can have Ga/Al ratios and some major and trace element values which overlap those of typical A-type granites. A-type granites probably result mainly from partial melting of F and/or Cl enriched dry, granulitic residue remaining in the lower crust after extraction of an orogenic granite. Such melts are only moderately and locally modified by metasomatism or crystal fractionation. A-type melts occurred world-wide throughout geological time in a variety of tectonic settings and do not necessarily indicate an anorogenic or rifting environment.
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The burning heart - The Proterozoic geology and geological evolution of the west Musgrave Region, central Australia
H.M. Howard,Robert H. Smithies,Christopher L. Kirkland,David E. Kelsey,Alan Aitken,Michael T.D. Wingate,R. Quentin de Gromard,Catherine V. Spaggiari,Wolfgang D. Maier +8 more
TL;DR: The Musgrave Province is one of the most geodynamically significant of Australia's Proterozoic orogenic belts, lying at the intersection of the continent's three cratonic elements as mentioned in this paper.
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TL;DR: In this article, structural field observations, in situ zircon U-Pb ages, Hf isotopic compositions, geochemistry, and Sr-Nd isotope data from the Puziba granitoid intrusions in the Qinling orogenic belt (China).
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Comagmatic A-type Granophyre and Rhyolite from the Alid Volcanic Center, Eritrea, Northeast Africa
TL;DR: Fenn et al. as discussed by the authors showed that granophyric textures are common in epizonal granitic bodies, particularly those associated with volcanic rocks (Buddington, 1959; Dunham, 1965).
Origin of the fluorine-rich highly differentiated granites from the Qianlishan composite plutons (South China) and implications for polymetallic mineralization
TL;DR: In this article, the authors proposed a different model for the origin of the granites and related mineralization, based on petrological and geochemical studies on the Qianlishan composite plutons that host the supergiant Shizhuyuan W-Sn-Bi-Mo deposit.
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Mesozoic granitic magmatism in extensional tectonics near the Mongolian border in China and its implications for crustal growth
TL;DR: The Yagan area of the southernmost Sino-Mongolian border is characterized by an extensional structure where a large metamorphic core complex (Yagan-Onch Hayrhan) and voluminous granitoids are exposed.
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