Ocean Drilling Program, United States

In order to evaluate X-ray imaging efficacy for observation and description of sedimentary structures in consolidated sedimentary rocks with a computed tomography (CT) scanner, X-ray images obtained during the Ocean Drilling Program Leg 210 cruise and X-ray CT images obtained during postcruise study are compared with split surface digital images of the correlative half-core. Sedimentary structures are clearly to faintly recognized with X-ray images, implying that sedimentary rocks (sandstone, siltstone, and shale) retain density contrasts despite decreases in porosity caused by compaction. X-ray imaging is efficient for observing partial sedimentary and postsedimentation structures. However, carbonate rocks tend to be unsuitable for X-ray imaging and observation because whole-core cementation often masks density contrasts, rendering homogeneous sedimentary structures. Overlap of high-angle structures often prevents clear two-dimensional imaging. X-ray CT scanning is a powerful tool that can image structures in sedimentary rock core samples before they are split. Constructing an efficient X-ray CT imaging methodology to be used during the time constraining the core description process is required.