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碳硅泥岩型铀矿床是我国铀矿地质工作者建立的铀矿床类型，是我国四大铀矿工业类型之一。桂西地区是我国华南地区一个重要的碳硅泥岩型铀矿床产出区域，包括大新（373）铀矿床等多个典型铀矿床（点）。研究辉绿岩与矿床成因的联系，对重新认识矿床成因有重要意义。本文在对桂西大新-钦甲地区碳硅泥岩型铀矿床和辉绿岩脉野外地质研究的基础上，系统研究了辉绿岩的地质特征、岩石学、地球化学特征以及其中锆石的U-Pb同位素年代学特征，在此基础上，探讨了辉绿岩的成岩与碳硅泥岩型铀矿床成矿间的关系。元素地球化学特征显示Rb、U、Th、Ba等大离子亲石元素的含量都高于MORB值，高场强元素Ta、Nb、Zr、Hf等均相对于MORB有所富集，而HREE元素中等亏损，表明本区辉绿岩属于富集地幔特征的板内碱性玄武岩系列（WPB），属于华南陆内伸展构造背景下软流圈上涌导致富集岩石圈地幔部分熔融形成的铁镁质岩浆发生侵位的产物。辉绿岩脉3个样品的锆石LA-ICP-MS U-Pb年龄为86.7±0.9Ma、89.05±0.96Ma、91.6±8.3Ma，表明形成于晚白垩纪早期，与华南地区与中基性岩脉有关的铀矿床成矿时代具有较好的对应关系，也与华南地区广泛分布的中生代基性岩脉时代一致，对应于华南白垩纪构造应力场中四次重要的拉张活动时代中的一期。辉绿岩脉锆石特征指示了辉绿岩成岩过程对矿源层中铀的活化所产生的重要作用以及成岩与成矿之间的热动力联系；结合元素地球化学、矿床成矿年龄和辉绿岩锆石U-Pb同位素年龄研究结果表明，区内铀矿床具有多期成矿特点，即'沉积期铀预富集、辉绿岩作用下二次预富集、后期热液再次富集成矿'，可能是该类型矿床成矿作用的重要形式。

An eco-environmental geochemical investigation was carried out in and around the Dexing mining area to determine the concentrations of heavy metals in the surface water, sediments, soils and plants. The main objective of this study is to assess the environmental situation and evaluate the transferring of heavy metals from mining activities into the food chain. Some samples of water, sediment, topsoil and plant were collected along the Lean River in the Dexing mining area. The total concentrations of Cu, Pb, Zn, Cd, and As were determined by AAS, and Hg was analyzed by cold-vapor AAS. Some indices such as ‘contamination degree’, ‘geoaccumulation index’, and ‘biological absorption coefficient’ were used to assess eco-environmental quality. The investigation indicated a highly localized distribution pattern closely associated with the two pollution sources along the Le' an, River bank: one is strong acidity and a large amount of Cu in the drainage from the Dexing Cu mining area; and the other is the high concentrations of Pb and Zn in the effluents released from many smelters and mining, processing and extracting activities in the riparian zone. Results from the investigated localities indicated, at least in part, that some problems associated with environmental quality deterioration should be solved in the future.

Mining and smelting activities are the main causes for the increasing pollution of heavy metals in soil, water body and stream sediment. An environmental geochemical investigation was carried out in and around the Panzhihua mining and smelting area to determine the extent of chemical contamination in soil and sediment. The main objective of this study was to investigate the environmental geochemistry of Ti, V, Cr, Mn, Cu, Pb, Zn and As in soil and sediment and to assess the degree of pollution in the study area. The data of heavy metal concentrations reveal that soils and sediments in the area have been slightly contaminated. Geochemical maps of Igeo of each heavy metal show that the contaminated sites are located in V-Timagnetite sloping and smelting, gangues dam. The pollution sources of the selected elements come mainly from dusts resultant from mining activities and other three-waste-effluents. The area needs to be monitored regularly for trace metal, especially heavy metal enrichment.

A total of 31 topsoil samples were systematically collected from the Panzhihua mining area including steel smelting, coal mining, urban and rural districts. A normalization procedure was adopted to establish the environmental geochemical baseline models for this area. By using the above baseline models, the regional geochemical baseline values of As, Cr, Cu, Ni, Pb and Zn were determined. On the basis of the baselines, the enrichment factors were used to analyze the mechanism of trace metal pollution in topsoil from anthropogenic sources, and the results showed that the serious trace metal pollution is caused by human activities in coal mine, iron mine, smelting factory, tailing dam and other industrial districts in the Panzhihua area.

The platinum group elements (PGE) in the mafic-ultramafic suite in the Xinjie layered intrusion and associated basalts and syenites were analyzed using neutron activation techniques after fire-assay preconcentration. On this basis, the geochemistry of the platinum group during the magmatic stage is discussed. With respect to PGE distribution, the Xinjie layered intrusion is similar to the Bushveld ferruginous ultramafic series and is distinct from komatiite and Alpine-type peridotite. It is also similar to the Emeishan basalt in PGE characteristics, implying that the original magmas of them may be of the same type.

Soil samples collected from different land-use regions have been analyzed for vanadium's speciation. The result shows that the content of soluble vanadium is lower than 1μg/g, while the content of residue occupies major part. As for soluble vanadium, the content in soil layer A1 is commonly lower than that in soil layer C; the content in soil from downstream of tailing dam is higher than that in soil from upstream of tailing dam; the content in glebe field soil is higher than that in paddy field soil; the content on soil profile indicates bottom enrichment. All above indicates soil Vanadium's accumulation in this region caused by years' mining activities. The results of Igeo and RAC are coincident, which show a low risk level of soil vanadium pollution.