赣南6722铀矿床隐爆碎屑岩地质构造特征与地下核爆炸地质效应的对比

COMPARISION BETWEEN THE GEOLOGICAL STRUCTURAL FEATURES OF FELSIC CRYPTOEXPLOSIVE BRECCIA OF NO. 6722 URANIUM DEPOSIT IN SOUTH JIANGXI PROVINCE AND THE GEOLOGICAL EFFECTS OF UNDERGROUND NUCLEAR EXPLOSION

对产出在花岗岩基底中的６７２２铀矿床长英质隐爆碎屑岩地质构造特征进行了研究，并与我国在相似地质条件下进行的地下核爆炸试验产生的地质效应作了对比，类比计算出形成该隐爆碎屑岩体的爆炸能量（ＴＮＴ当量）。采用偏光显微镜和透射电镜（ＴＥＭ）研究隐爆碎屑岩中花岗岩角砾内石英的显微裂隙构造、光性特征及自由位错的类型和密度，并与基底花岗岩（大富足花岗岩体）中的石英进行对比。综合研究阐明６７２２铀矿床隐爆碎屑岩的形成机制属于一种在高温（＞４００℃）条件下由瞬间爆炸而产生的脆性变形作用，同时引起石英中位错退火现象的发生。

Based on a comparision between the geological structural features of felsic cryptoexplosive breccia within granitic basement of No. 6722 uranium deposit and the geological effects of underground nuclear explosion, the explosion equivalent of TNT for cryptoexplosive breccia of No. 6722 uranium deposit is calculated by a comparision method. The microfissuring optic features, and ultramicrostructure of quartz for cryptoexplosive breccia and basement granite have been studied respectively under the polarization microscope and transmision electron microanalyzer(TEM). The densely parallel directional microfissuring, similar to impact microfoliation(shock lamellae), is observed in quartz grains of cryptoexplosive breccia for No. 6722 uranium deposit, but undulatory extinction is not found. It has been found under the TEM that the free dislocations and dislocation walls are sparsely distributed in quartz grains of basement granite, but sharply reduced and even disappeared in quartz grains of granite breccia. The results of a comprehensive study suggest that the cryptoexplosion forming mechanism of No. 6722 uranium deposit is attributed to a brittle deformation due to instantaneous explosion which simultaneously caused the annealing of dislocations in quartz.