排序方式: 共有50条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
The Huangshannan magmatic Ni-Cu sulfide deposit is one of a group of Permian magmatic Ni-Cu deposits located in the southern Central Asian Orogenic belt in the Eastern Tianshan, northwest China. It is characterized by elevated Ni tenor (concentrations in recalculated 100% sulfide) in sulfide within ultramafic rocks (9–19 wt%), with values much higher than other deposits in the region. Sulfides of the Huangshannan deposit are composed of pentlandite, chalcopyrite, and pyrrhotite and the host rock is relatively fresh, indicating that the high-Ni tenor is a primary magmatic feature rather than formed by alteration processes. It is shown that sulfides with high-Ni tenor can be generated by sulfide-olivine equilibrium at an oxygen fugacity of QFM +0.5, for magmas containing 450 ppm Ni and 20% olivine. Ores with >10 wt% sulfur have relatively low PGE and Ni tenors compared to other ores, R factor (mass ratio of silicate to sulfide liquid) modeling of Ni indicates that they formed at moderate R values (150–600). Based on this constraint on R values, ores with <10 wt% sulfides in the Huangshannan deposit can be segregated from a similar parental magma with 0.05 ppb Os, 0.023 ppb Ir, and 0.5 ppb Pd at R values between 600 and 3000. This, coupled with the supra-cotectic proportions of sulfide liquid to cumulus silicates in the Huangshannan ores imply mechanical transport and deposition of sulfide liquid in a magma pathway or conduit, in which sulfides must have interacted with large volumes of silicate magma. Platinum and Pd depletion relative to other platinum group elements (PGEs) are observed in fresh and sulfide-rich samples (S > 4.5 wt%). As sulfide-rich samples are also depleted in Cu, and as interstitial sulfides in those samples are physically interconnected at a scale of several cms, the low Pt and Pd anomalies are attributed to solid Pt and Pd phases crystallization and retention with the monosulfide solid solution (MSS) and Cu-rich sulfide liquid percolation during MSS fractionation. This finding indicates that Pt anomalies in sulfide-rich rocks from magmatic Ni-Cu deposits in the Eastern Tianshan are the result of sulfide fractionation rather than a hydrothermal effect. 187Os/188Os(278Ma) values of the lherzolite samples vary from 0.27 to 0.37 and γOs(278Ma) values vary from 110 to 189, indicating significant magma interaction with crustal sulfides, rich in radiogenic Os. Well constrained γOs values and δ34S values (−0.4 to 0.8‰) indicate that crustal contamination occurred at depth before the arrival of the magma in the Huangshannan chamber. Regionally, deposits with high-Ni tenor have not been reported other than the Huangshannan deposit; however, many intrusions with high-Ni contents in olivine are present in NW China, such as the Erhongwa, Poyi and Poshi intrusions. Those intrusions are capable of forming high-Ni tenor sulfides due to olivine-sulfide-silicate equilibrium and relative high-Ni content in parent magma, making them attractive exploration targets. 相似文献
5.
This study presents a new and first finding of Au-Pb intermetallic compounds in the Inagli Pt–Au placer deposit, the Republic of Sakha (Yakutia), Russia. This is the first time that all three accepted minerals (hunchunite, anyuiite and novodneprite), as well as unnamed Au-Pb intermetallics, corresponding in composition to Au1.5Pb and AuPb, are present together in the same locality. We provide chemical compositions of Au-Pb compounds and host gold particles, describe morphology and relationships between different mineral phases. We also present an unexpected finding of unusual inclusion of Pb-Fe-aluminosilicate associated with K-feldspar and anyuiite in the gold grain. The new data together with data from other occurrences of Au-Pb compounds worldwide were reviewed to discuss type localities, mineralogy, conditions and possible mechanisms of formation of Au-Pb intermetallics and to provide an overview of current knowledge about these uniquely rare but naturally occurring minerals. 相似文献
6.
7.
中国与基性—超基性岩有关的Cu-Ni(Pt)矿床成矿系列类型 总被引:2,自引:0,他引:2
中国与基性—超基性岩有关的Cu-Ni(Pt)矿床,主要形成于以前寒武系为基底的大陆裂谷,部分形成于增生褶皱带中显生宙地层为基底的裂陷槽环境。根据形成时代、当时所在的构造环境单元及成矿岩浆系列,划分为9个矿床成矿系列和8个矿床成矿亚系列。成矿时代以元古代、晚古生代为主。现今,矿床主要分布于地台边缘,造山带中也有产出,但不代表其当时形成的地质背景。成矿物质来源为上地幔,原始岩浆以上地幔部分熔融的高MgO拉斑玄武岩(拉斑橄榄玄武岩)岩浆系列为特征,也有钙碱性岩浆(喀拉通克)和科马提岩岩浆系列(桂北)。地壳物质混染比较普遍。矿床成因类型主要为岩浆熔离型,且以硅酸盐岩浆上侵前的深部熔离作用为主。还有热液成因类型(煎茶岭)。矿床成矿系列的时空分布与中国大陆的构造演化密切相关 相似文献
8.
9.
样品采用王水溶解,二氯化锡还原,泡沫塑料富集,用Re作内标,电感耦合等离子体质谱法同时测定土壤中超痕量金、铂、钯。在盐酸-二氯化锡体系中,盐酸酸度为15%,二氯化锡浓度为45 g/L,吸附时间30 min时吸附效果明显,吸附温度为25℃时吸附率相对稳定。方法检出限Au为0.21 ng/g,Pt为0.18 ng/g,Pd为0.16 ng/g,方法加标回收率Au为91.3%~97.8%,Pt为92.0%~96.7%,Pd为96.0%~101.6%。该方法用于测定国家一级标准物质,线性范围宽、重现性好,结果准确可靠,样品处理简便、快速。 相似文献
10.
聚氨酯泡塑富集硫脲解脱-石墨炉原子吸收光谱法测定地质样品中金铂 总被引:1,自引:4,他引:1
泡沫塑料常用于富集常规地质样品中的铂族元素,而富集后往往用高温灰化法解脱,此法操作繁琐,温度过高易使铂配合物分解为王水难以提取的不溶性残渣,导致测试结果不稳定、效率低;单独使用20 g/L硫脲溶液解脱,测试结果的重现性差。本文对此方法进行改进,采用50%王水封闭溶解试样,氯化亚锡还原,聚氨酯泡塑富集,20 g/L硫脲-20%盐酸溶液解脱,石墨炉原子吸收光谱法测定金和铂。在盐酸-氯化亚锡体系中,吸附温度为20℃,振荡时间为30 min时,金和铂的回收率均在95%以上,金和铂的检出限分别为0.23 ng/g和0.39 ng/g,精密度(RSD,n=10)分别为1.8%~10.3%和1.3%~13.3%。经国家一级标准物质验证,测定值和标准值基本相符。该方法泡塑解脱时无需高温灰化,用王水多次提取,在100℃沸水浴中即可一次完成,样品处理快捷。与高温灰化法相比,提取温度大为降低,分析流程简单,显著提高了单次测样量,且干扰小、空白值低,可以满足除王水难溶的铂矿种外大部分地质样品快速测定的需要。 相似文献