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Redox State of the Granitic Rocks and Formation of the Scheelite Skarn in the Xintianling Deposit, Nanling Range, South China
Author(s) -
ZHANG Rongqing,
LU Jianjun,
WANG Rucheng,
HU Jiabin,
ZHANG Huaifeng
Publication year - 2014
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.12367_31
Subject(s) - skarn , scheelite , china , geochemistry , chinese academy of sciences , geology , mining engineering , archaeology , geography , fluid inclusions , metallurgy , materials science , paleontology , quartz , tungsten
The ore-element associations are closely associated with the relative oxidation state and the degree of fractional crystallization. Study on the redox state of granite is a valid reference on discriminating rock types and prospecting ore elements. In general, Mo, Cu and Au mineralization is associated with oxidized granite, whereas Sn is related to the reduced granite (Blevin and Chappell, 1992). Tungsten occurs as W in evolved granitic melt, which is weakly controlled by redox state. In Australia and Japan, tungsten deposits could occur as W-Mo-Cu and WSn-F series, corresponding oxidized and reduced granites, respectively (Blevin and Chappell, 1992; Kwak and White, 1982). Most skarn minerals have compositional variations that can yield significant information about the skarn evolution and can be used to differentiate skarn types. Garnet and pyroxene compositions in skarns are particularly important as they can indicate redox condition of a skarn system. Stable isotope are of great help in understanding the origin of specific hydrothermal ore deposits. The Xintianling granite complex, associated with a large scheelite skarn deposit, is situated in the middle Nanling Range, South China. This skarn deposit is the third largest tungsten deposit in China, ranking only second to the Dahutang and Shizhuyuan deposits. In this study, we systematically analyzed the whole-rock geochemistry, Sr-Nd-Hf-Pb isotopes, and chemical compositions of rock-forming and accessory minerals to constrain the petrogeneis of the granitic rocks in the Xintianling deposit. Meanwhile, the redox state of the granitic rocks is evaluated based on the magnetic susceptibility, magnetite/ilmenite ratios, Fe/Fe ratios of biotite and Ce abnormities of zircons. we also observed the paragenesis of different skarn minerals, and analyzed mineral chemical compositions together with C-H-O-S isotopes to discuss the physico-chemical conditions of skarn.