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Geoscience ›› 2017, Vol. 31 ›› Issue (06): 1157-1169.

• OPetrology • Previous Articles     Next Articles

Zircon U-Pb Geochronology, Petrogeochemistry of Huangniupu Plutons in Western Section of the North Qinling Mountains and Their Geological Significance

YAO Zheng(), ZHANG Yafeng, YANG Tao, YI Pengfei, ZHENG Shuxin   

  1. Shaanxi Center of Geological Survey, Xi’an, Shaanxi 710068, China
  • Received:2016-12-12 Revised:2017-05-04 Online:2017-12-10 Published:2017-12-25

Abstract:

The research on LA-ICP-MS zircon U-Pb geochronology and petrogeochemistry of Huangniupu plutons is carried out. Results show that the zircon U-Pb age of Huangniupu plutons is (449.3±4.9) Ma, which indicates that the formation age of Huangniupu plutons is Late Ordovician. Huangniupu plutons belong to high-k calc-alkaline series with quasi-aluminous feature, which has the mineral and geochemical characteristics in genetic type of I-type granite. The REE distribution patterns reveal that Huangniupu plutons have a right-wing type with LREE enrichment, HREE depletion (LREE/HREE=9.83-11.55) and weak negative Eu anomaly (δEu=0.82-0.95), and the trace elements show the enrichment in Rb, Th, U, Sm and obvious depletion in Ta, Nb, Ti, Hf, which is consistent with the geochemical features of magmatic rocks formed in island-arc. Combined with the regional geological data, it is concluded that Huangniupu plutons were formed in the island arc setting during Shangdan Ocean subduction in Late Ordovician and generated by the crustal-mantle magma mixing, which provides more sufficient and accurate evidences of magmatic activities for the further study on the tectonic evolution of the North Qinling Mountains.

Key words: western section of North Qinling Mountain, Huangniupu pluton, LA-ICP-MS dating, petrogeochemistry

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