The majority of samples for this study are from the world's oldest (~170 Ma) in situ oceanic crust cored in Hole 801C. The physical properties of these primary crystalline rocks removed from depth and measured at atmospheric pressures are strongly related to both the original porosity and secondary porosity because of stress unloading and the coring process. Alteration products, infilling of fractures and voids with secondary phases, and contributions from sediment also influence the physical state of the recovered oceanic crust. Thus, physical properties measurements are indicators of lithologic type, texture, and degree of alteration and are used to assess the physical state of the oceanic crust with depth and to establish the correlation between downhole measurements and cored material. The results of shore-based measurements of resistivity and X-ray computer tomography (CT) of over 100 discrete cube-shaped samples from Hole 801C and Site 1149 are presented in Tables T1 and T2, respectively. Resistivity measurements on cored samples are particularly useful for a number of reasons; it is a measurement that is also obtained from the borehole wall by downhole instruments, and it is strongly dependent on porosity, type and amount of pore fluid present, and pore structure geometry. These attributes are, in turn, the most important variables controlling density and velocity in the basalts cored in Hole 801C. Evaluation of physical properties measurements to assess the physical state of oceanic crust are presented in R.D. Jarrard, L.J. Abrams, R. Pockalny, R.L. Larson, and T. Hirono (unpubl. data) and Hirono (this volume).
X-ray CT measurements of discrete samples of oceanic crust, sediments, and sedimentary rocks were obtained to image in a nondestructive measurement of internal structures in an attempt to further quantify pore geometry. It was hoped that these images would provide constraints for permeability measurements (Hirono, this volume); however, pore geometry was not resolvable using this technique.