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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Geochemistry and geochronology of Mesoproterozoic basement rocks from the Eastern Amery Ice Shelf and southwestern Prydz Bay, East Antarctica: Implications for a long-lived magmatic accretion in a continental arc
TL;DR: The high-grade metamorphic rocks from the eastern Amery Ice Shelf and southwestern Prydz Bay of East Antarctica represent reworked Rayner Complex during the late Neoproterozoic/Cambrian metamorphism.
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Elemental and Sr-Nd isotopic geochemistry of Cretaceous to Early Paleogene granites and volcanic rocks in the Sikhote-Alin Orogenic Belt (Russian Far East): implications for the regional tectonic evolution
TL;DR: In this paper, the authors carried out zircon U-Pb dating, and whole-rock elemental and Sr-Nd isotopic analyses on granites and volcanic rocks from the Primorye region of southern Sikhote-Alin.
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U-Pb and Re-Os geochronology and geochemistry of the Donggebi Mo deposit, Eastern Tianshan, NW China: Insights into mineralization and tectonic setting
Huashan Sun,Huan Li,Martin Danišík,Qinglin Xia,Chuling Jiang,Pan Wu,Hui Yang,Qianrong Fan,Dongsheng Zhu +8 more
TL;DR: The Donggebi Mo deposit located in NW China is a newly discovered, large, stockwork-type Mo deposit with ore reserves of 441mt @ 0.115% Mo as discussed by the authors.
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Petrogenesis and magmatic evolution of ∼130 Ma A-type granites in Southeast China
TL;DR: In this paper, the Sanqingshan-Damaoshan (SD) granites were investigated using zircon U-Pb geochronology, Hf isotopic analyses, and major and trace element analyses.
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Origin of peralkaline granites of the Jurassic Bokan Mountain complex (southeastern Alaska) hosting rare metal mineralization
TL;DR: The Jurassic Bokan Mountain complex (BMC) as mentioned in this paper is composed of arvedsonite and/or aegirine-bearing peralkaline A-type granitic rocks.
References
Trace element discrimination diagrams for the tectonic interpretation of granitic rocks
TL;DR: In this article, a data bank containing over 600 high quality trace element analyses of granites from known settings was used to demonstrate using ORG-normalized geochemical patterns and element-SiO2 plots that most of these granite groups exhibit distinctive trace element characteristics.
Tectonic setting of basic volcanic rocks determined using trace element analyses
Julian A. Pearce,J.R. Cann +1 more
TL;DR: In this paper, the results of analyses for Ti, Zr, Y, Nb and Sr in over 200 basaltic rocks from different tectonic settings have been used to construct diagrams in which these settings can usually be identified.
3.6K
Nature and origin of A-type granites with particular reference to southeastern Australia
TL;DR: In the Lachlan Fold Belt of southeastern Australia, Upper Devonian A-type granite suites were emplaced after the Lower Devonian I-type granites of the Bega Batholith as mentioned in this paper.
2.1K
Zircon and granite petrology.
TL;DR: In this paper, a genetic classification of zircon populations from granitic rocks is proposed, with three main divisions: (1) granites of crustal or mainly crustal origin (sub) autochthonous and aluminous granites)]; (2) hybrid granites (calc-alkaline and sub-alkalinized series granites); (3) granite of mantle or mainly mantle origin (alkaline, tholeiitic series granite).
1.2K