再谈黎平敖市金刚石异常——贵州省当前最佳金刚石找矿靶区分析

Discussion of diamond abnormality of Aoshi in Lipin Analyses of the best diamond target area in Guizhou province

诸多迹象表明,敖市金刚石异常为一浓集异常,且叠加在一辉石重砂异常之上,显示出强烈的近源补给特征,其补给源极有可能是具工业价值的金刚石原生矿。鉴于湘黔金刚石成矿区内已知的含金刚石钾镁煌斑岩及其相关岩体的同位素年龄值均在375~475 Ma范围,其成矿期显然属加里东晚期,而紧邻敖市异常尚有后加里东盖层残留,作为幔源火山作用产物的金刚石原生矿如果出现在此种盖层附近,所遭后加里东期剥蚀将极其有限,不至像已知马坪原生矿那样失去工业价值。在该区未来的找矿工作中,应从本区的实际出发,选定合适指示矿物组合,应坚持运用大、中、小样相结合分级控制不同级别径流的重砂法和取样时先除去沉积物表层的成功经验,而不宜硬套国外的模式。

It＇s inferred that the Aoshi diamond abnormality is a concentration abnormality,added a pyroxene heavy mineral anomaly,then it shows strong proximal supplying feature,its supplying source may is the commercial diamond primary deposit.Because the isotopes age of the known diamond bearing lamproite and the relative ore bodies is between 375 to 475Ma,the metallogenic epoch is Late Caledonian,there is post Caledonian relict close to the Aoshi abnormality,if the diamond primary deposit,as a outcome of mantle source volcanism,appears nearby this kind of caprock,the denudation of the potential primary diamond deposit is limited,so it won＇t lose the commercial value like Maping primary deposit.In the future exploration,it must depend on the reality in the area and choose suitable index mineral association,it should uses the successful experiences of heavy mineral method and remove the sediment surface before sampling but uses the foreign method.