Platinum-group elements in the oxide layers of the Hongge mafic-ultramafic intrusion, Emeishan Large Igneous Province, SW China

	Platinum-group elements in the oxide layers of the Hongge mafic-ultramafic intrusion, Emeishan Large Igneous Province, SW China
	Zhong-Jie Bai; Hong Zhong; Chusi Li; Wei-Guang Zhu; Gui-Wen Xu
通讯作者	Hong Zhong
	2012
发表期刊	Ore Geology Reviews
卷号	46 期号:1-2 页码:149-161
摘要	The Hongge layered intrusion (259.3 +/- 1.3 Ma) is one of several mafic-ultramafic intrusions that host giant Fe-Ti-V oxide ore deposits in the similar to 260 Ma Emeishan Large Igneous Province (ELIP), SW China. The Hongge intrusion consists of a lower olivine clinopyroxenite zone (LOZ), a middle clinopyroxenite zone (MCZ) and an upper gabbro zone (UGZ). Most of the 14 to 84 m-thick and 300 to 1700 m-long economic Fe-Ti-V oxide ore layers occur within the MCZ. This paper reports the concentrations of PGE in the oxide layers of the Hongge intrusion. Unlike in the economic PGE (platinum-group elements) mineralized (up to 1.2 ppm Pt and 1.8 ppm Pd) coeval Xinjie intrusion (259 +/- 3 Ma), the oxide layers in the Hongge intrusion contain very low PGE (total PGE: 0.09-63.5 ppb). Chromite-bearing horizons in the Hongge intrusion are enriched in IPGE (Ir: 0.46-0.65 ppb; Ru: 2.25-3.29 ppb) relative to PPGE (Pt: 0.54-1.28 ppb; Pd: 0.30-0.90 ppb). In contrast, the massive magnetite layers in the Hongge intrusion show no IPGE enrichments relative to PPGE. All our samples from the Hongge intrusion collectively show no correlation between PGE and S contents, and weak positive correlations between IPGE and Cr contents, indicating removal of Ir. Ru from magma with crystallization of chromite. Positive correlations exist between IPGE and PPGE in the samples, indicating that all of the PGE was controlled by sulfide liquid. Most of the samples have mantle-normalized PGE patterns with a slope similar to that of the Emeishan picritic basalts, which are less fractionated than the coeval high-Ti basalts derived from the same Fe-, Ti-, V-rich magma series. The Hongge oxide-rich samples are characterized by Cu/Pd ratios (1.47-202 x 10(4)) significantly higher than those for primitive mantle and the coeval picrites (0.99 x 10(4)). The PGE tenors in bulk sulfides (i.e., in recalculated 100% sulfides) in the sulfide-bearing oxide ores of the Hongge intrusion (<0.1-3 ppm) are 2-3 orders of magnitude lower than the Xinjie intrusion (10-100 ppm). This, together with extremely high Cu/Pd ratios in both sulfide-bearing and sulfide-barren oxide-rich samples, indicates that the parental magma of the Hongge intrusion was depleted in PGE. We suggest that PGE depletion in the Hongge parental magma was due to previous sulfide segregation at depth, mainly due to crustal contamination. The PGE-depleted sulfides in the Hongge intrusion are thought to have formed by second-stage sulfide saturation and segregation due to fractional crystallization involving abundant magnetite after magma emplacement at Hongge.
关键词	Platinum-group Elements Layered Intrusions Magnetite Layers Sulfide Segregations Hongge Intrusion Emeishan Large Igneous Province
学科领域	矿床地球化学
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/352002/4847
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
通讯作者	Hong Zhong
推荐引用方式 GB/T 7714	Zhong-Jie Bai,Hong Zhong,Chusi Li,et al. Platinum-group elements in the oxide layers of the Hongge mafic-ultramafic intrusion, Emeishan Large Igneous Province, SW China[J]. Ore Geology Reviews,2012,46(1-2):149-161.
APA	Zhong-Jie Bai,Hong Zhong,Chusi Li,Wei-Guang Zhu,&Gui-Wen Xu.(2012).Platinum-group elements in the oxide layers of the Hongge mafic-ultramafic intrusion, Emeishan Large Igneous Province, SW China.Ore Geology Reviews,46(1-2),149-161.
MLA	Zhong-Jie Bai,et al."Platinum-group elements in the oxide layers of the Hongge mafic-ultramafic intrusion, Emeishan Large Igneous Province, SW China".Ore Geology Reviews 46.1-2(2012):149-161.

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