Abstract
The Shimensi deposit (Northern Jiangxi, South China) is a recently discovered super-large tungsten deposit. Muscovite 40Ar/39Ar dating yielded a plateau age of 145.7 ± 0.9 Ma, with normal and inverse isochronal ages being 145.4 ± 1.4 Ma and 145.3 ± 1.4 Ma, respectively. The muscovite 40Ar/39Ar age, which can represent the mineralization age, coincides well with the published zircon U–Pb ages (143–148 Ma) of the ore-hosting granites, which indicates that the tungsten mineralization was syn-magmatic. The new age reported here confirms that the Shimensi tungsten deposit is part of a large Early Cretaceous (147–136 Ma) tungsten-polymetallic belt in South China. Measured and calculated sulfur isotopic compositions (δ34Sminerals = −3.0‰ to 1.1‰, average −1.3‰; δ 34 S H 2 S = −4.5‰ to +1.2‰, average −1.8‰) of the Shimensi ore-forming fluids indicate that the sulfur was mainly magmatic-derived. The calculated and measured oxygen and hydrogen isotopic compositions ( δ 18 O H 2 O = 4.1‰ to 6.7‰, δD = −62.7‰ to −68‰) of the ore-forming fluids indicate a dominantly magmatic source with a meteoric water input. Oxygen isotopic modelling of the boiling/mixing processes indicates that the Shimensi tungsten mineralization was caused mainly by fluid mixing of magmatic hydrothermal fluid with meteoric water.
Highlights
South China is well endowed with tungsten resources
Unlike southern Jiangxi, where tungsten mineralization is associated with tin, tungsten mineralization in northern Jiangxi is associated with copper [3]
The muscovite was incrementally heated by 13 steps from 700 ◦ C to 1220 ◦ C and yielded a concordant age spectrum
Summary
South China is well endowed with tungsten resources. Previous exploration efforts were concentrated in the Nanling region (especially southern Jiangxi). Fractionation of the granitic magma, metals were concentrated in the late magmatic hydrothermal fluids and deposited as giant orebodies via a two-stage magmatism and mineralization process. The ore-fluid circulation model has been proposed, and fluid driving factors are mainly ascribed to process. The ore-fluid circulation model has been proposed, and fluid driving factors are mainly temperature and pressure gradients [9]. Previous exploration mainly focus on wolframite, whereas recent exploration has good potential of veinlet/disseminated scheelite The possible ore-forming fluid sources [1,14] and their interactions in metals transportation, as well as the mineralization age [7,8,15] remain poorly constrained.
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