Evaluation of the Geological, Geophysical and Hydrogeological Conditions at Kamlunge

摘要

The Kamlunge study site constitutes a 16 km exp 2 mountain plateau. The topography of the plateau is flat, the soil cover is thin, and in the western part, there is a high percentage of outcrops. The most commonly occurring rock types are gneisses and red granite (Lina granite). A rock type with granodioritic to dioritic composition also occurs. Concentrations of economically valuable minerals are so small that mining operations are not feasible in the area. The rock mass exhibits a fracture frequency of more than 4.0 fractures per metre down to a depth of 200 metres. Below 300 metres, the fracture frequency is approximately 2.0 fractures per metre. The Kamlunge study site is surrounded by regional fracture zones to the north, east and west delimiting a 16 km exp 2 triangular block. The regional zone to the west of the study site has a width of about 550 m. Only local fracture zones spaced 500-l 500 m. apart occur within the study site. The local fracture zones are generally steeply inclined and strike to the north-west and the north-east. At a depth of 555 m below Kamlungekoelen, a horizontal fracture zone has been encountered in 4 of the deep drill holes. This fracture zone is permeable to water but less crushed and weathered than the steeply inclined fracture zones. Moreover, horizontal fractures of large lateral extent can occur in the upper 100-200 metres. Common fracture minerals in the fracture zones are calcite, chlorite, laumontite, smectite and various types of iron oxides. The hydraulic conductivity of the rock mass decreases markedly with depth. It decreases from about 2 x 10 exp -9 m/s at a depth of 100 metres to about 10 exp -11 m/s at a depth of 500 metres. The hydraulic conductivity of the local fracture zones at Kamlunge is 7 x 10 exp -10 m/s at a depth of 500 m. The hydraulic conductivity decreases with depth more slowly in the fracture zones than in the rock mass. (Atomindex citation 15:043665)