Lithogeochemical, Re–Os and U–Pb Geochronological, Hf–Lu and S–Pb Isotope Data of the Ga'erqiong‐Galale Cu–Au Ore‐Concentrated Area: Evidence for the Late Cretaceous Magmatism and Metallogenic Event in the Bangong‐Nujiang Suture Zone, Northwestern T

Abstract

The Ga'erqiong-Galale skarn-porphyry copper-gold ore-concentrated area is located in the western part of the Bangong-Nujiang suture zone north of the Lhasa Terrane. This paper conducted a systematic study on the magmatism and metallogenic effect in the ore-concentrated area using techniques of isotopic geochronology, isotopic geochemistry and lithogeochemistry. According to the results, the crystallization age of quartz diorite (ore-forming mother rock) in the Ga'erqiong deposit is 87.1 ± 0.4 Ma, which is later than the age of granodiorite (ore-forming mother rock) in the Galale deposit (88.1 ± 1.0 Ma). The crystallization age of granite porphyry (GE granite porphyry) in the Ga'erqiong deposit is 83.2 ± 0.7 Ma, which is later than the age of granite porphyry (GL granite porphyry) in the Galale deposit (84.7 ± 0.8 Ma).The quartz diorite, granodiorite, GE granite porphyry and GL granite porphyry both main shows positive εHf(t) values, suggesting that the magmatic source of the main intrusions in the ore-concentrated area has the characteristics of mantle source region. The Re-Os isochron age of molybdenite in the Ga'erqiong district is 86.9 ± 0.5 Ma, which is later than the mineralization age of the Galale district (88.6 ± 0.6 Ma). The main intrusive rocks in the ore-concentrated area have similar lithogeochemical characteristics, for they both show the relative enrichment in large-ion lithophile elements(LILE: Rb, Ba, K, etc.), more mobile highly incompatible lithophile elements(HILE: U, Th) and relatively depleted in high field strength elements (HFSE: Nb, Ta, Zr, Hf, etc.), and show the characteristics of magmatic arc. The studies on the metal sulfides' S and Pb isotopes and Re content of molybdenite indicate that the metallogenic materials of the deposits in the ore-concentrated area mainly come from the mantle source with minor crustal source contamination. Based on the regional tectonic evolution process, this paper points out that the Ga'erqiong-Galale copper-gold ore-concentrated area is the typical product of the Late Cretaceous magmatism and metallogenic event in the collision stage of the Bangong-Nujiang suture zone.

Petrogenesis and metallogenic implications of Cretaceous magmatism in Central Lhasa, Tibetan Plateau: A case study from the Lunggar Fe skarn deposit and perspective review

“…Abundant Cu–Au and Pb–Zn–(Ag) mineralization has also been recognized during the Paleocene, Eocene, and Miocene from Southern Lhasa (Z. Q. Hou, Duan, et al, ; Z. Q. Hou, Yang, et al, ; X. Sun, Zheng, Xu, et al, ; Z. Zhang, Chen, et al, ; Z. Zhang, Yao, et al, ) associated with the closure of the Neo‐Tethyan ocean and India–Asia collision.…”

“…The major ore minerals in the Fe deposits are magnetite and minor limonite, and gangue minerals include garnet, epidote, and diopside. (b) Ga'erqiong‐Galale (~87 Ma; Z. Zhang, Yao, et al, ) and Balazha (~90 Ma; H. X. Yu, Chen, et al, ) porphyry‐skarn Cu–Au–Mo deposits in the central and western domains. The Cu–Au–Mo ore bodies are spatially associated with porphyry intrusions, composed of chalcopyrite, molybdenite, and pyrite (H. X. Yu, Chen, et al, ; Z. Zhang, Yao, et al, ).…”

“…(b) Ga'erqiong‐Galale (~87 Ma; Z. Zhang, Yao, et al, ) and Balazha (~90 Ma; H. X. Yu, Chen, et al, ) porphyry‐skarn Cu–Au–Mo deposits in the central and western domains. The Cu–Au–Mo ore bodies are spatially associated with porphyry intrusions, composed of chalcopyrite, molybdenite, and pyrite (H. X. Yu, Chen, et al, ; Z. Zhang, Yao, et al, ). (c) Chagele (~72 Ma; B. D. Wang, Guo, et al, ) and Mengya'a (~64 Ma; L. Q. Wang, Tang, et al, ) granite‐related Pb–Zn deposits (Late Cretaceous/Early Paleocene) in the east.…”

“…Ages are compiled from Chu et al (), Qu, Xin, Xu, Yang, and Li (), Kang, Xu, Dong, and Wang (), C.Y. Zhou et al (), H. Zhou, Qiu, Yu, and Wang (), Zhu, Mo, Niu, et al (), Zhu, Mo, Wang, et al (), Zhu et al (), Y. M. Gao et al (), J. H. Gao, Zeng, Gao, Hou, and Guo (), X. Jiang et al (), W. Liu, Li, Yuan, Zhang, et al (), W. Liu, Li, Yuan, Zhou, et al (), W. Liu, Li, Yang, and Yuan (), F. Y. Meng et al (), F. Y. Meng et al (), F. Q. Li et al (), Y. X. Li et al (), X. Y. Li et al (), Y. Li et al (), G. C. Fei, Wen, Wang, Wu, et al (), G. C. Fei, Wen, Wang, Zhou, et al (), F. Fei et al (), Du, Qu, Wang, Xin, and Liu (), H. X. Yu, Chen, et al (), Y. S. Yu, Gao, et al (), Cui et al (), B. D. Wang, Guo, et al (), B. D. Wang et al (), Wang, Zheng, et al (), L. Q. Wang, Tang, et al (), L. Q. Wang, Xie, and Wang (), L. Y. Wang, Zheng, Gao, et al (), L. Y. Wang, Zheng, Yang, et al (), L. Q. Wang et al (), Yao et al (), X. Q. Zhang, Zhu, et al, , L. L. Zhang et al (), X. Q. Zhang, Zhu, et al (), Y. J. Zhang, Liu, Zhu, An, and Liao (), Z. Zhang, Chen, et al (), Z. Zhang, Yao, et al (), K. X. Huang et al (), Y. Chen et al (), J. L. Chen, Xu, et al (), S. S. Chen, Fan, et al (), S. S. Chen, Shi, et al (), Z. Q. Hou, Duan, et al (), G. Y. Sun, Hu, Sinclair, et al (), G. Y.…”

“…Central Lhasa hosts numerous ore deposits, including the Nixiong and Lunggar Fe skarn deposits (~113–116 Ma; S. F. Fan et al, ; F. Fei, Yang, Liu, Zhao, & Yu, ; Y. S. Yu, Gao, et al, ; Y. S. Yu, Yang, Tian, et al, ), the Ga'erqiong‐Galale and Balazha Cu–Au deposits (~87–90 Ma; H. X. Yu, Chen, et al, ; Zhang, Chen, et al, ; Zhang, Yao, et al, ), and the Chagele and Longmala Pb–Zn–Ag deposits (~62–63 Ma; S. B. Gao et al, ; Wang et al, ; L. Q. Wang, Tang, et al, ). These mineral deposits are believed to be genetically related to Cretaceous magmatism (Y. C. Zheng, Fu, et al, ).…”