1. Tourmaline chemical composition and boron isotopic composition at the Longmenshan pegmatite in Dahongliutan area, West Kunlun: Implication for rare-metal Li-Be mineralization.
- Author
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Yao, Jun-Ming, Li, Feng-Ling, Ma, Guan-Zhong, Zhang, Xue-Bing, Hou, Ke-Jun, Yang, Hong-Yun, and Li, Nuo
- Subjects
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BORON isotopes , *TOURMALINE , *NONFERROUS metals , *MINERALIZATION , *SOLID solutions , *BORON - Abstract
[Display omitted] • The tourmalines in Longmenshan are divided into two types, compositionally belongs to alkali group and schorl-dravite solid solution series. • The δ11B of the Tur-I tourmalines indicate the fluids that are responsible for the formation of tourmalines were derived mostly from the granitic magmas with little exotic oxide fluids involved. • The large range of B isotope variation indicates that the Tur-II tourmaline are more obviously affected by fluid activity. Tourmaline is a common mineral in rocks. It can record geological information during its formation and is a geochemical tracer. Its in-situ element and boron isotope tests provide a broader application perspective. Therefore, the chemical and boron isotope characteristics of tourmaline can be used to trace the mineralization of pegmatite-type rare metals. West Kunlun is an important Li-Be metallogenic belt, and many important Li-Be deposits have been developed. Longmenshan is one of the recently discovered pegmatite-type Li-Be deposits in the Dahongliutan area. There are barren and spodumene-bearing pegmatites that all contain tourmaline in Longmenshan. According to their occurrence, crystal form, and chemical composition, the tourmalines in Longmenshan are divided into two types: Tur-I tourmaline in the barren pegmatite close to the granite and Tur-II tourmaline from the spodumene-bearing pegmatite. Compositionally belongs to the alkali group and schorl-dravite solid solution series, with Tur-I being mainly schorl and Tur-II being schorl-dravite. Tur-I tourmalines are rich in Li, Sn, V, Cr, Zn, and Mn, while Tur-II tourmalines are rich in Be, Sr, and Sc. The δ11B of the Tur-I tourmalines hosted in the barren pegmatite and Tur-II from the spodumene-bearing pegmatite ranges from −8.38‰ to −6.81‰ and from −10.00‰ to −6.41‰, respectively. These characteristics indicate that the formation fluid of tourmaline in Longmenshan is mainly derived from magma, and other fluids are rarely involved. The large range of B isotope variation indicates that the Tur-II tourmalines are more obviously affected by fluid activity. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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