城口地区早寒武世黑色岩系铂族元素地球化学特征与来源

发布时间：2018-03-06 20:26

本文选题：铂族元素　切入点：黑色岩系　出处：《矿物学报》2017年04期 　论文类型：期刊论文

【摘要】：北大巴山城口地区广泛发育富集V、Ag、Se等多种元素的下寒武统黑色岩系,但是否存在铂族元素矿化以及来源一直存在争议。本文利用ICP-MS方法测定了城口地区孙家坝剖面下寒武统鲁家坪组(对应牛蹄塘组)黑色岩系多金属富集层的铂族元素(PGE)、Au和Ag含量,在判断铂族元素异常的基础上,利用铂族元素地球化学特征探讨其来源。结果表明,该剖面黑色岩系样品具有较高的PGE含量(32.2~142.5 ng/g),平均88.9 ng/g,与上地壳平均值对比具有明显的PGE富集特征;同时金、银也具有较高的含量,平均值分别为40.2 ng/g和31.7μg/g。铂族元素配分模式表现为相对富集Pd、Pt、Os、Ru,亏损Ir、Rh,依据Ir含量以及与球粒陨石的对比分析,认为鲁家坪组黑色岩系PGE不具备地外物质来源。铂族元素球粒陨石标准化配分模式、PGE含量顺序及铂族元素相关图解显示其来源可能与海底热水作用关系密切。有机碳和PGE含量之间没有明显相关性,表明有机质可能是通过改变氧化还原条件导致PGE进一步富集。城口地区埃迪卡拉纪-寒武纪过渡阶段海底热水作用和PGE异常的识别不仅对于理解黑色岩系型矿床的成因,而且对全球重大事件如寒武纪生命大爆发的认识都具有重要意义。
[Abstract]:The Lower Cambrian black rock series, which is rich in various elements such as VDU AgSe and other elements, is widely developed in Chengkou area of Bashan, Peking University. In this paper, ICP-MS method was used to determine the platinum group in the polymetallic enrichment layer of the lower Cambrian LU Jiaping formation (corresponding Niutetang formation) in the Sunjiaba section of Chengkou area. The contents of au and Ag, On the basis of judging the anomaly of platinum group elements, the geochemical characteristics of platinum group elements are used to discuss its origin. The black rock series samples in this section have a high PGE content of 32.2n 142.5 ng / g, with an average of 88.9 ng / g, and have obvious PGE enrichment characteristics compared with the average value of the upper crust, and the gold and silver contents are also relatively high. The average values were 40.2 ng/g and 31.7 渭 g / g, respectively. The platinum-group partitioning pattern was characterized by relative enrichment of PD PtO Osn Ruand and depletion of Ir-Rh.According to ir content and comparative analysis with chondrites, It is considered that the PGE of the black rock series of the Lujiaping formation does not have a source of extraterrestrial material. The PGE content sequence of the standardized partitioning model of chondrites of platinum group elements and the diagram of the elements of platinum group may be closely related to the interaction of submarine hot water. There was no significant correlation between carbon content and PGE content. It is suggested that the organic matter may be further enriched by changing the redox conditions. The identification of submarine hot water and PGE anomalies during the transition from Edikala to Cambrian in Chengkou area is not only helpful in understanding the genesis of the black rock series deposits. Moreover, the understanding of the major global events such as Cambrian life explosion is of great significance.
【作者单位】：外生成矿与矿山环境重庆市重点实验室重庆地质矿产研究院;煤炭资源与安全开采国家重点实验室重庆研究中心;重庆市地质调查院;
【基金】：国土资源部公益性行业科研专项项目(批准号:201311105) 国家自然科学基金项目(批准号:41602172) 重庆市国土资源和房屋管理局科研项目(批准号:CQGT-KJ-2014010;KJ-2016013) 重庆市基础科学与前沿技术研究项目(编号:cstc2017jcyj AX0364)
【分类号】：P618.53

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