Measurements of the permeability of the sheeted dikes in Hole 504B, ODP Leg 111

An inflatable drill-string packer was used to measure the in-situ bulk permeability of two zones within the sheeted dikes that comprise the deepest 500-600 m of the hole. Previous measurements had shown that the upper 200 m of pillow lavas in the hole is fairly permeable, at about 10^-14-10^-13 m². In contrast, Anderson et al. (1985a, 1985b) measured a much lower bulk permeability of about 10^-17 m² over an interval of >700 m that includes the deeper 400 m of extrusives and the upper 300 m of sheeted dikes. Results indicate that the sheeted dikes have bulk permeabilities on the order of 10^-18 to 10^-17 m², comparable to the value measured by Anderson et al. (1985a, 1985b) in the deeper extrusives and upper sheeted dikes. Thus, except for the permeable upper 200 m of pillow lavas, most of the 1287.8 m of basaltic basement cored in Hole 504B is relatively impermeable. -from Author