Germanium isotopic systematics in Ge-rich coal from the Lincang Ge deposit, Yunnan, Southwestern China

	Germanium isotopic systematics in Ge-rich coal from the Lincang Ge deposit, Yunnan, Southwestern China
	Hua-Wen Qi; Olivier Rouxel; Rui-Zhong Hu; Xian-Wu Bi; Han-Jie Wen
	2011
发表期刊	Chemical Geology
卷号	286 期号:3-4 页码:252-265
摘要	Organic matter plays an important role in the transport and precipitation of germanium (Ge) in coal-hosted Ge deposits. In this paper, Ge isotopes of coal samples and their combustion products were analyzed in order to investigate the potential use of Ge isotopes as tracers of Ge sources and enrichment mechanisms in coal.Germanium isotopic composition of various samples (mainly Ge-rich lignite) from the Lincang Ge deposit,Yunnan, Southwest China was analyzed using a continuous flow hydride generation system coupled to a Multi Collector Inductively Coupled Plasma Mass Spectrometer (MC-ICP-MS) and the standard-sample bracketing approach. Variations of 74Ge/70Ge ratios are expressed as δ74Ge values relative to NIST SRM 3120a Ge standard solution. Ge-rich lignite samples show large Ge isotopic fractionation (δ74Ge values range from −2.59‰ to 4.72‰), and their δ74Ge values negatively correlate with Ge concentrations. Lignite samples with low Ge concentrations (b500 ppm) tend to show positive δ74Ge values, while δ74Ge values of lignite samples with high Ge concentrations (N1000 ppm) are close to zero or negative. Along stratigraphic sections, Ge is mainly concentrated in the top or the bottom of the coal seam, such that high values of δ74Ge are usually found in the middle part of the coal seam. Interlayered hydrothermal chert and limestone samples in Ge-rich coal seams also show moderate fractionation (δ74Ge values range from −0.14‰ to 2.89‰ and from 0.55‰ to 1.87‰,respectively). The overall variations of δ74Ge values of Ge-rich lignite and organic-rich chert samples can be well described by a Rayleigh fractionation model, indicating that preferential enrichment of light Ge isotopes in coal in an open system might be the main factor controlling Ge fractionation in Ge-rich lignite. The germanium isotopic composition of hydrothermal chert (and possibly limestone) might also record the competitive fractionation produced by precipitation of quartz and sorption of coal. Elevated Ge concentrations and/or δ74Ge values of some chert, limestone, sandstone, and claystone samples may be attributed to themixing with Ge-rich organic matter. Furthermore, similar to the fractionation of Zn, Cd and Hg isotopes observed between refinery dust or gas and slag, high temperature coal combustion also fractionates Ge isotopes, with the Ge isotopic compositions of soot being distinctly lighter (up to 2.25 per mil) than those of cinder. The distinct enrichment of potential hazardous elements (i.e., Pb, Cd, and As) and Ge in soot after coal combustion, as well as the common enrichment of Ge in sulfide minerals (e.g. sphalerite), highlights the possibility of using Ge isotopes as useful tracers of sources of heavy metal pollution caused by high temperature industrial processes (coal combustion and Pb-Zn refining) in the environment
关键词	Germanium Coal Stable Isotope Fractionation Water–rock Interaction Geochemical Tracer
收录类别	SCI
语种	英语
文献类型	期刊论文
条目标识符	http://ir.gyig.ac.cn/handle/352002/4088
专题	矿床地球化学国家重点实验室_矿床地球化学国家重点实验室_期刊论文矿床地球化学国家重点实验室
通讯作者	Hua-Wen Qi
推荐引用方式 GB/T 7714	Hua-Wen Qi,Olivier Rouxel,Rui-Zhong Hu,et al. Germanium isotopic systematics in Ge-rich coal from the Lincang Ge deposit, Yunnan, Southwestern China[J]. Chemical Geology,2011,286(3-4):252-265.
APA	Hua-Wen Qi,Olivier Rouxel,Rui-Zhong Hu,Xian-Wu Bi,&Han-Jie Wen.(2011).Germanium isotopic systematics in Ge-rich coal from the Lincang Ge deposit, Yunnan, Southwestern China.Chemical Geology,286(3-4),252-265.
MLA	Hua-Wen Qi,et al."Germanium isotopic systematics in Ge-rich coal from the Lincang Ge deposit, Yunnan, Southwestern China".Chemical Geology 286.3-4(2011):252-265.

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