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Geoscience ›› 2017, Vol. 31 ›› Issue (02): 234-245.

• Mineralogy, Petrology and Mineral Deposit • Previous Articles     Next Articles

Age,Geochemistry and Petrogenesis of Granites from Badaguan Area in Northern Hailaer, Inner Mongolia

LI Yan1,2(), WANG Jian1(), SUN Deyou1, CHEN Debing2, HAN Zhibin2, CUI Jiarui2   

  1. 1. College of Earth Sciences, Jilin University, Changchun, Jilin 130061, China
    2. No.240 Institute of Nuclear Industry, Shenyang, Liaoning 110032, China
  • Received:2016-05-11 Revised:2016-10-15 Online:2017-04-10 Published:2017-04-25

Abstract:

The granite of Badaguan is mainly composed of syenogranite and monzonitic granite. Zircon U-Pb isotopic dating yields age of (212±1.7)-(226.7±1.6) Ma, indicating that they were formed in the Late Triassic. The granites are metaluminous with A/CNK ratios of 1.01-1.10 and differentiation index (DI) of 92.5-95.8. The granites are enriched in K, Rb and LREE, and depleted in Ba, Sr and HFSE, e.g., Nb, Ta, P and Ti, with moderate Eu negative anomalies (δEu=0.51-0.71). The relatively low values of 10,000 Ga/Al (average at 1.91), low zircon saturation temperature (average at 683 ℃) and other geochemical features suggest that the syenogranite and monzonitic granites in the study area are high differentiation I-type granites. The zircons in the granites show high values of εHf(t) (4.50-10.45) with two-stage Hf model ages of 0.59-0.97 Ga, suggesting that they are derived from the newly formed crust which is separated from Neo-Proterozoic depleted mantle. Combined with the U-Pb ages and other geochemical features, we proposed that the granite of Late Triassic formed in an active continental margin setting of the Mongolian-Okhotsk oceanic plate.

Key words: granite, zircon U-Pb dating, petrogenesis, tectonic setting, Badaguan

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