贵州镇远钾镁煌斑岩原生及砂矿金刚石矿物学特征及其找矿意义  

Mineralogical characteristics of lamproite-hosted and placer diamonds from Zhenyuan,Guizhou and their significance for primary deposit prospecting

作　　者：黄远成[1] 李志翔[2,3] 丘志力[2] 饶红娟[1] 陆太进[4] 陈华[4] 柯捷[4] 魏然[4] 

机构地区：[1]贵州省地矿局101地质大队,贵州凯里556000 [2]中山大学地球科学与地质工程学院,广东广州510275 [3]广东省珠宝玉石交易中心,广东广州511483 [4]国土资源部珠宝玉石首饰管理中心,北京100013

出　　处：《中山大学学报（自然科学版）》2016年第5期108-118,共11页Acta Scientiarum Naturalium Universitatis Sunyatseni

基　　金：国家自然科学基金资助项目(41272086;41473030);国土资源部公益性行业科研基金资助项目(200811012)

摘　　要：扬子克拉通原生金刚石矿找矿一直是极具争议性的问题。金刚石及其寄主岩石蕴含了深部岩石圈地幔丰富的地球化学信息,可为原生矿找矿提供重要的约束和指示。通过对贵州101地质队过去发现的镇远钾镁煌斑岩区199颗原生金刚石及周围水系中16颗砂矿金刚石的形态学(包括表面微细生长)和熔蚀特征的对比,并结合红外光谱测试,进一步探讨了贵州金刚石携带的地质找矿信息。新的测试结果显示,贵州原生金刚石具有颗粒普遍较小、破碎度大、存在(95%)强烈熔蚀、表面附着物丰富、发蓝白色荧光、所有样品均无磷光等特点,红外无损测试确认Ⅱa型金刚石的产出比例高,但低于原先部分学者估算的比例;通过与砂矿金刚石对比,确认所测试样品的寄主钾镁煌斑岩不可能是贵州或湖南沅水已发现砂矿金刚石的直接源岩,扬子克拉通应当还存在其他规模性的金刚石原生矿或者来源;通过野外实地考察及室内样品测试,确认所研究的钾镁煌斑岩为浅部相,而非根部相,暗示贵州镇远地区原生金刚石找矿仍有较大潜力。There has not been an agreement reached for a long time on the occurrence, host rocks and genesis of primary diamond deposits beneath the Yangtze Craton, China. In this paper, the surface features and FTIR of 199 macro diamonds from lamproite rocks and 16 diamonds from the surrounding river basins in Zhenyuan collected by No. 101 Guizhou Geological Brigade were studied by non-destructive techniques including FTIR spectroscopic techniques, aiming at finding out valuable geological prospecting information/indication. The results showed that most primary diamonds are small in size and fragmentized, and are characterized by strong dissolution features or attaching materials on surface. Most diamonds display blue-white fluorescence other than phosphorescence. FTIR results confirmed the majority of the diamonds are type IIa, but their proportion is less than previous estimation and observation. Compared with Hunan and Guizhou placer diamonds, it is believed that the host lamproite rocks of the primary diamonds in Zhenyuan is not the primary source of those placer diamonds discovered in Guizhou and Hunan provinces. Based on field survey and research of the geological occurrence, it is concluded that lamporite rocks in Zhenyuan may be shallow phase rather than deep root phase, implying it has the potential to discover new primary diamond deposits in Guizhou.

关 键 词：原生金刚石 钾镁煌斑岩 找矿 扬子克拉通 贵州 

分 类 号：P619.24[天文地球—矿床学]