Open AccessTourmaline geochemistry and boron isotope variations as a guide to fluid-rock interaction in the Qinghe pegmatite, NW China
Author(s) -
Beiqi Zheng
Publication year - 2021
Publication title -
iop conference series. earth and environmental science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.179
H-Index - 26
eISSN - 1755-1307
pISSN - 1755-1315
DOI - 10.1088/1755-1315/783/1/012012
Subject(s) - pegmatite , tourmaline , geology , geochemistry , empa , electron microprobe , mineralogy
The alteration zone around pegmatites can be used as a direct tool to trace the property of pegmatite-derived fluids. In the present study, EPMA, LA-ICP-MS, and MC-ICP-MS were used to analyze major elements, trace elements and boron isotope compositions of tourmaline from Qinghe barren pegmatite, NW China. Most tourmalines from the pegmatite are schorl, while the remaining tourmalines from the pegmatite, the contact zone, the altered wall rock and the unaltered wall rock are dravite. All tourmalines follow the exchange vector (Fe + Mg) (Al + X vac ) −1 , indicating enriched Fe and Mg. The Fe 3+ Al −1 exchange vector and increase of V/Sc in the late stage suggest sudden destruction of the pegmatite system. The δ 11 B indicates that a small scale fluid exsolution occurred in the late stage. Compared with other fertile pegmatites around the world, Qinghe pegmatite has the most negative δ 11 B and lower Li content, indicating that both the source and evolution process have an impact thereon.