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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Citations
Syn- and post-collisional granitoids in the Central Tianshan orogen: Geochemistry, geochronology and implications for tectonic evolution
TL;DR: In this paper, the authors show that four granitic plutons, muscovite granites (MG), biotite monzonitic granite (BMG), and alkali granites(AG), have been recognized to have intruded in the Mishigou area, Central Tianshan Belt.
186
Granites in the Sawuer region of the west Junggar, Xinjiang Province, China: Geochronological and geochemical characteristics and their geodynamic significance
TL;DR: In this article, the authors used SHRIMP U-Pb dating results to show that the granites in the Sawuer region were formed between 337-Ma and 290.7-Ma (late Carboniferous and early Permian).
185
High-Temperature Granite Magmatism, Crust–Mantle Interaction and the Mesoproterozoic Intracontinental Evolution of the Musgrave Province, Central Australia
Robert H. Smithies,H.M. Howard,Paul M. Evins,Christopher L. Kirkland,David E. Kelsey,Martin Hand,Michael T.D. Wingate,Alan S. Collins,Elena Belousova +8 more
TL;DR: The Pitjantjatjara Supersuite as discussed by the authors was formed by the breakdown of F-rich biotite in a crustal granulite, which was then partially cooled but were remobilized during subsequent under- and intraplating events.
182
Important crustal growth in the Phanerozoic: Isotopic evidence of granitoids from east-central Asia
TL;DR: In this article, a very large volume of juvenile crust produced in the period of 500 to 100 Ma in several orogenic belts was revealed, including the East-Central Asian Orogenic Belt (ECAOB), eastern part of the Altaid Tectonic Collage, and Mongolia and Transbaikalia.
Geochronology and geochemistry of a Mesozoic magmatic arc system, Fiordland, New Zealand
TL;DR: The median tectonic zone in Eastern Fiordland, SW New Zealand, comprises a tectonically disrupted belt of Mesozoic magmatic arc rocks related to subduction along the palaeo-Pacific margin of Gondwana as mentioned in this paper.
180
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