【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。更多还原

【Abstract】 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.更多还原