Geochemistry of Nb-Enriched Gabbros in Zhaigen Area in Northern Qinling and Their Tectonic Significance
Zhao Ligang
Li Chengdong
Xu Yawen
Wu Zhiyu
Chang Qingsong
Xu Teng
Teng Xueming
Abstract：Nb-enriched gabbros are often associated with high-Mg diorite and adakite, which is considered to be a petrotectonic association of facies significance.However, this kind of magmatic activity has seldom been found in the southern side of the North Qinling orogenic belt in western Henan.Based on the method of petrology, geochemistry, isotope geochemistry and chronology for amphibolites from the Qinling Group in Zhaigen area, the Nb-enriched gabbros were separated from the deep plutonic complex in this study.The results show that the U-Pb age of metamorphic zircons from Nb-enriched gabbros is484.3±1.8Ma, which is similar to the peak of metamorphic ages of the UHP eclogites in this area.Nb-enriched gabbros are characterized by enrichment of Rb, Th and other heavy ion lithophilic elements and depletion of Nb, Ta, P and other high field strength elements.εNd (t) values range from-1.61to+0.49, and (87Sr/86Sr) ivalues range from 0.714 273to 0.723 936.We speculated that their formation was related to the remelting of mantle wedge peridotite by partially melted plate melts during the deep subduction of the Qinling paleocontinental crust.And a large amount of continental crust was added to the deep subduction.The discovery of Nb-enriched gabbros provides evidence for the existence of multiple small continental blocks in the Early Paleozoic of the Qinling orogen.
Keywords：Nb-enriched gabbrosgeochemistryZhaigenthe Qinling orogenic belt
Publication Date：2019-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：10( 135-144 )