Abstract
Hydraulic conductivity of drilling core specimens recovered from melanges in the Mino terrane was measured by transient pulse technique. The core specimens were taken from the melanges of middle Jurassic Kamiaso unit in the Maruyama-dam area, which were thermally metamorphosed by latest Cretaceous Toki Granite, and from the non-metamorphosed melanges of late Jurassic to earliest Cretaceous Kanayama unit. Both of them have sandstone blocks several mm to several cm in diameter within a sheared shale matrix. Coefficients of hydraulic conductivity of the former range from 10-13 to 10-15m/sec, whereas those of the latter is 10-11 to 10-15m/sec; It indicates that the melanges are low permeability rocks, and that the thermal metamorphism may decrease the hydraulic conductivity of the melanges. The coefficients of hydraulic conductivity are not mutually related with the angles between long axis of the specimen (direction of the water flow) and foliation of the melange. On the other hand, the hydraulic conductivity increases with the increases of the porosity. The melanges from the Kanayama unit show a weak relationship between the hydraulic conductivity and the amounts of sandstone blocks in the melanges ; the coefficients increase with the increase of amounts of sandstone blocks. Coefficients of hydraulic conductivity reported in published papers and measured by the in situ tests at about same depth with the specimens of this report, are clustered around 10-7m/sec.
