Deep geological features of Jijicao granite in Beishan pre-selected area for the disposal of high-level radioactive waste

Jijicao granite is one of the potential ones in Beishan pre-selected area for the disposal of high-level radioactive waste in China. Deep geological information on lithology, fault and size of this granite have been gained by drilling eight boreholes. There is only one main type of lithology in the deep, called biotite adamellite with very low alteration, the same as that in the surface. The degree of denudation is very low, for there are metomorhpic relicts in near-surface of granite. There are two faults in the center of granite with one north-west water non-conductive fault which broken products have been cemented, and with another north-east water conductive fault which broken products have not been cemented. The vertical shape of near-surface granite both in north-east and north-west edge looks like a tongue, which thickness is less than 100 m, extending into its outside metamorphic rock. The depth of granite in the center has been proved more than 600 m. Above deep geological information provides direct evidences for the repository site selection in this granite. (authors)