中文摘要:文章首次明确提出黔东南天柱县、锦屏县、黎平县以及相邻的湖南省靖县、会同县、洪江县存在浊积岩型金矿。研究发现,这些金矿均产在加里东皱褶带中,它们产于背斜的轴部,向两翼延伸,形成平行于地层的石英脉;另一种石英脉则充填于褶皱和剪切作用形成的剪切带或断裂带中。这些褶皱和断裂均呈北东方向。黔东南地区的浊积岩型金矿,均赋存于前震旦系下江群浊积岩中,产在板岩、凝灰岩或者在板岩和砂岩交界处。石英脉中金的富集与黄铁矿、毒砂、闪锌矿、方铅矿等密切相关。细脉比宽脉更富集金,断裂交叉处更富含金。石英脉两侧(尤其是顺层石英脉)的蚀变很弱,主要为硅化和绿泥石化。应用RB_SR方法测得石英脉的年龄为370~450 Ma,成矿时代应在加里东期或期后。黔东南浊积岩金矿在品位(多数可见明金)、储量和产量方面均很有前景,研究它具有十分重要的学术价值和经济意义。
Abstract:Southeast Guizhou area is a gold province, as shown by the well developed primary gold mineralization in the Precambrian rocks of the southeast Guizhou and southwest Hunan Caledonian fold belt. More than twenty gold deposits have been found in the area, with gold produced both from primary quartz veins and from alluvial placer deposits. Precambrian Xiajiang Group, with minor Sinian and Cambrian sediments, dominates exposed bedrocks. Mesozoic sediments are not well developed in this area. The Precambrian Xiajiang Group, which has been subdivided into Panzao, Qingshuijiang, Pinglue and Longli Formations, is characterized by a turbidite sequence composed of slate, meta_sandstone, meta_tuff and siltstone. This succession was deformed by NE_trending folds and NEE_dipping thrust faults and shear zones. No intrusion and dyke have been found in this area. The Precambrian Xiajiang Group and the Lower Cambrian sediments experienced low_grade regional weak greenschist facies metamorphism. Three mineralization types have been identified in the region, namely, auriferous quartz veins mostly parallel to the bedding (BPV), discordant quartz veins filled into shear zones and normal faults, and placer deposits. The vein type deposits can be subdivided into three types: ① high grade (approximately 16 g/t Au) narrow gold_bearing veins, ② low grade (0.5~4 g/t Au) thicker gold_bearing quartz veins, and ③ bedding cross cutting quartz veins (3~6 g/t Au) with intensive alteration. Recent studies show that the Au contents in turbidite and in pyrite of turbidite are higher than the Au Clarke value (4×10-9). This indicates that the reaction between the turbidite and pyrite as the possible source of gold and the probable hydrothermal fluids finally led to the formation of this type of deposits.
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基金项目:中国科学院海外人才基金(2003104002452)和贵州省省长科学技术基金(GSJ03102)
引用文本:
卢焕章,王中刚,陈文一,吴学益,朱笑青,胡瑞忠.2006.贵州东南部浊积岩中金矿的地质特征和成因[J].矿床地质,25(4):369~387卢焕章,王中刚,陈文一,吴学益,朱笑青,胡瑞忠.2006.Turbidite hosted gold deposits in southeast Guizhou: Their structural control, mineralization characteristics, and some genetic constrains [J].Mineral Deposits25(4):369~387
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