Data report: descriptive evaluation of consolidated sedimentary rock structures with X-ray imaging: examples from Site 1276 core samples

Abstract

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.

Data report: three-dimensional observation and quantification of internal structure of sediment core from Challenger Mound area in Porcupine Seabight off western Ireland using a medical X-ray CT

“…X-ray imaging is also efficient for observing dropstones and pebbles. However, Shirai et al (2007) suggested that carbonate rocks might be unsuitable for X-ray imaging because cementation often obscures density contrasts, rendering sedimentary structures homogeneous. When CT numbers are selected in narrower ranges, which is more suitable for observation of sedimentary structures, coral fragments can be clearly distinguished on CT images (Fig.…”

“…Changes in point of view are conspicuous in some features. Ashi (1997) and Shirai et al (2007) suggest that some lamina sets drastically change in visibility according to changes in observation direction. 3-D imaging with an X-ray CT system can be observed from any angle.…”

“…doi:10.2204/iodp.proc.307.209.2009 2 Geological Survey of Japan, AIST, Tsukuba Central 7, 1-1-1 Higashi, Tsukuba 305-8567, Japan. Correspondence author: akiko-tanaka@aist.go.jp (CT) scanner (e.g., Iturrino et al, 2004;Shirai et al, 2007). In this paper, we describe and discuss the use of medical X-ray CT to map coral fragments within host sediments.…”

Value of X-ray computed tomography in the scientific ocean drilling

“…This paper was presented at the 2011 JAPT Geology and Exploration Symposium entitled "Petrophysics -Current applications and challenges for evaluation of rock properties" held in Tokyo, Japan, on June 8, 2011. most of the studies focused on structural and physical property analyses of sediments (Soh et al, 1993；Ashi, 1995；Soh, 1997；Ashi, 1997；Iturrino et al, 2004, Tanaka et al, 2011 , only few others worked on geotechnical properties (Rutledge et al, 1995) , core screening and structural analysis on consolidated sedimentary rocks (Shirai et al, 2007) as well.…”