U–Pb geochronology, geochemistry, and H–O–S–Pb isotopic compositions of the Leqingla and Xin'gaguo skarn Pb–Zn polymetallic deposits, Tibet, China. (1st January 2016)

• Record Type: Journal Article
• Authors: Wang, Liqiang; Cheng, Wenbin; Tang, Juxing; Kang, Haoran; Zhang, Yan; Li, Zhuang
• Is Part Of: Journal of Asian earth sciences. Volume 115(2016)
• Page Start: 80
• Page End: 96
• Publication Date: 2016-01-01
• Subjects: Geochronology -- Geochemistry -- Isotopic compositions -- Ore-forming fluids and metals -- Leqingla -- Xin'gaguo -- Gangdese; Earth sciences -- Asia -- Periodicals; Sciences de la terre -- Asie -- Périodiques; Earth sciences; Asia; Periodicals; 555.05
• DOI: 10.1016/j.jseaes.2015.09.018
• Languages: English
• ISSNs: 1367-9120

Abstract

Highlights: Mineralization ages for the Leqingla and Xin'gaguo deposits are 60.8 and 56.5 Ma, respectively. Both the Leqingla and Xin'gaguo deposits were formed on the geological setting of the India–Asia continental collision. Ore-forming metals for these two deposits were sourced from the Neo-Tethys Ocean slab and the Lhasa terrane basement. Abstract: The Leqingla and Xin'gaguo deposits are two representative skarn Pb–Zn polymetallic deposits of the Gangdese Pb–Zn polymetallic belt, Tibet, China. LA-ICP-MS zircon U–Pb dating of the mineralization-related biotite granites from both the Leqingla and Xin'gaguo deposits yielded weighted mean ages of 60.8 Ma and 56.5 Ma, respectively, which can be inferred as their mineralization ages. The Leqingla biotite granite is characterized by high Al2 O3, total Fe, Na2 O, and low K2 O. In comparison, the Xin'gaguo biotite granite is characterized by relative higher K2 O but lower Al2 O3, total Fe, and Na2 O. Geochemical and mineralogical characteristics indicate that the Leqingla and Xin'gaguo biotite granites are calc-alkaline I-type granite and High K calc-alkaline I-type granite, respectively. Both the Leqingla and Xin'gaguo biotite granites are enrichment in LREE and LILEs and depletion in HFSEs, and they were formed at the India–Asia collision stage. δ 18 O and δD values for the Leqingla and Xin'gaguo deposits are −8.8‰ to 5.3‰ and −140.4‰ to −90.1‰, −4.5‰ to 7.0‰ and −117.3‰ to −81.0‰, respectively, indicating magma fluids mixed with meteoric water in ore-forming fluids. δ 34 S values (−11.6‰ to −0.3‰) of ore sulfides from the Leqingla deposit show characteristics of biogenetic sulfur isotope compositions, suggesting sulfur for the Leqingla deposit were sourced from wall rocks of the Mengla and Luobadui Formation, which are rich in organic materials. δ 34 S values of ore sulfides from the Xin'gaguo deposits show bimodal distribution (−5.0‰ to −1.6‰ and 1.6–2.1‰), indicating sulfur in the Xin'gaguo deposit were derived from both wall rocks and magma. In the Leqingla deposit, most ore sulfides have the similar Pb isotopic compositions with that of the mineralization-related biotite granite, suggesting the biotite granite supplied most of the ore-forming metals. Pb isotopic compositions of ore sulfides and Hf isotopic compositions of biotite granite show that the majority of ore-forming metals are derived from mantle components of partial melting of the Neo-Tethys Ocean slab, with some upper crust materials of the Lhasa terrane. Pb isotopic compositions of ore sulfides from the Xin'gaguo deposit are similar to that of the Leqingla deposit, indicating they have the similar sources of ore-forming metals.