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Late Paleozoic south-ward accretionary polarity of the eastern Junggar orogenic belt: insight from the Dajiashan and other A-type granites
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2008
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Other A-type GranitesEarth ScienceEngineeringEastern JunggarIgneous PetrogenesisGeographyTectonic EvolutionDajiashan Alkali GraniteGeologyMineral DepositGeochemistryMineral GeochemistryGeochronologyOrogenyPetrologySouth-ward AccretionTectonics
The Dajiashan alkali granite is situated at the central parts of the Kalameili-Haerlike granitic belt of Eastern Junggar, Northwest China.LA-ICPMS zircon U-Pb dating shows that its crystallization age is 284±1Ma.The Dajiashan alkali granite is characterized by high absolute SiO_2,Alkali(A/CNK1,AR=3.9～6.67)abundance,low CaO and Al_2O_3;high FeO_T/MgO and 10000 * Ga/Al ratios;enriched REE(except Eu),LILE(Rb,U,Th,K)and some HFSE(Zr,Hf,Nb,Ta);strongly depleted Ba, Sr P,Ti,Eu;Y/Nb(2.71～3.75)1.2.All these facts reveal that the Dajiashan alkali granite is a Permian A_2-type granite.The distribution of ages of the other A-type and late-orogenic granites belts in the Eastern Junggar area indicates a south-ward younging trend,which is good agreement with the south-ward accretion.