高放废物地质处置北山预选区芨芨槽岩块地质特征

芨芨槽岩块是高放废物地质处置北山预选区新场地段中有利候选岩块之一。以高精度卫片解译、野外踏勘、地表工程揭露和节理测量为主要手段，对此岩块的岩石、断裂、节理带和节理等地质特征进行了详细调查和研究。芨芨槽岩块的主岩岩石类型单一，为黑云母二长花岗岩；后期有煌斑岩脉和石英脉贯人。断裂以NE向为主，共7条；多数断裂分布于岩块东西两侧边界，而岩块内部只有2条断裂。节理带以NW向为主，长度大于1km的有8条。据统计，岩块中节理有4个优势组，各优势组的产状和间距分别服从正态和负指数分布，节理平均间距为1．2-1．6m。断裂对节理的影响范围小于100m。此项调查和研究为处置库选址、性能评价和设计提供了必要的基础资料。

Geological feature of Jijicao block in Beishan pre-selected area for the disposal of high level radioactive waste

Jijicao is one of the most potential blocks in Xinchang section of Beishan area, which is selected for the disposal of high-level radioactive waste. Based on the high-resolution satellite image interpretation, geological survey, trench survey and joint measurement, the geological characterization of its petrology, fault, joint zone and joint have been investigated in detail. There is only one type of rock, called biotite adamellite in this block with some lamprophyre and quartz veins invaded later. There are 7 faults in the block, most of them are with a direction of northeast, but only two faults are located in the center and others located in the east and west border respectively. There are 8 joint zones with a length more than 1 km and most of them with a direction of northwest. According to their attitude, joints can be divided into 4 groups. The results of statistical analysis show that the attitude and spacing of each joint group obey normal distribution and negative exponential distribution respectively. The mean joint spacing is from 1.2 m to 1.6 m. The affected scope from fault to joint is less than 100 m. The results of this investigation provide some necessary basical information for site selection, performance assessment and repository design.