贵州施秉下翁哨地区镁铝榴石及铬尖晶石重砂异常地球化学指示源岩  

Geochemical analyses of the placer anomaly with high content of pyrope and chrome-spinel in Xiawengshao area, Shibing County, Guizhou Province

作　　者：李永刚[1,2] 杨光忠 石睿[1] 林泽渊[1] 张与伦 周宗赞 康丛轩 LI Yonggang;YANG Guangzhong;SHI Rui;LIN Zeyuan;ZHANG Yulun;ZHOU Zongzan;KANG Congxuan(No.101 Geological Party, Bureau of Geology and Mineral Exploration and Development of Guizhou Province, Kaili 556000, Guizhou, China;School of Earth Sciences, China University of Geosciences, Wuhan 430074, Hubei, China;Nanjing Center, China Geological Survey, Nanjing 210016, Jiangsu, China)

机构地区：[1]贵州省地矿局101地质大队,贵州凯里556000 [2]中国地质大学(武汉)地球科学学院,湖北武汉430074 [3]中国地质调查局南京地质调查中心,江苏南京210016

出　　处：《地质通报》2019年第1期143-151,共9页Geological Bulletin of China

基　　金：贵州省地矿局基金项目<施秉下翁哨地区镁铝榴石重砂异常及其矿物学研究>(编号:黔地矿科合(2016)02号)

摘　　要：以往资料显示,贵州施秉下翁哨地区镁铝榴石和铬尖晶石自然重砂,高度浓集于下翁哨盆地北岸对门坡一带新近系翁哨组含砾粘土岩和盆地南侧2km处斜坡带"不明成因"砂砾石堆积物中,构成罕见的高含量重砂异常,在贵州众多金刚石找矿信息中尤为瞩目,其来源及其金刚石找矿指示意义长期成谜。通过对盆地南侧2km处斜坡带"不明成因"砂砾石堆积物采样分析查证,原样中镁铝榴石为2.7粒/L,铬尖晶石大于5.0粒/L,异常客观存在;电子探针研究表明,镁铝榴石和铬尖晶石分属G9镁铝榴石和S5贫钛高铝富镁铬铁矿,其来源与金伯利岩关系不大。Existing data reveal that there exists the placer anomaly with high content of pyrope and chrome-spinel in Xiawengshao area, Shibing County, Guizhou Province. It is distributed in the gravel-clay rock from the Neogene Wengshao Formation in Duimenpo area on the northern side of the Xiawengshao basin, and the“unexplained”deposits of sand-gravel in the slope zone, 2km south side of the Xiawengshao basin. Such a phenomenon constitutes the high content of placer anomalies, which is prominent among lots of information related to diamond prospecting in Guizhou Provence. The source of these minerals and its significance to the exploration of diamonds have remained unsolved for a long time. Based on the analysis of the“unexplained”deposits of sandgravel in the slope zone, 2km south side of the Xiawengshao basin, it is found that the 2.7grains/L and Chrome-spinel>5.0 grains/L of original magnesia-alumina pyrope prove the existence of the anomaly. Results from electron microprobe analysis revealed that the pyrope is classified as G9-pyrope, and the picotite as S5-chromite that is poor in titanium but abundant in aluminum and magnesium. Their source has little relation with kimberlite.

关 键 词：自然重砂异常 镁铝榴石 铬尖晶石 电子探针 含矿性指示意义 

分 类 号：P619.241[天文地球—矿床学]