Average dip directions from intervals of dipmeter log in drill hole CRP-2A

• Main Authors: Jarrard, Richard D, Brink, Jason, Bücker, Christian J, Wonik, Thomas, Wilson, Terry, Paulsen, Timothy S
• Format: Dataset
• Language: English
• Published: PANGAEA 2000
• Subjects: 14.2 km at 096° true from Cape Roberts; Azimuth; Bed dip; Cape Roberts Project; Compass; Confidence; Core wireline system; CRP; CRP-2; CRP-2A; CWS; Depth; bottom/max; top/min; Number; Obliquity/tilt; off Cape Roberts; Ross Sea; Antarctica; Sample code/label; Sampling/drilling from ice; Student_s t; Antarc*
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.143836; https://doi.org/10.1594/PANGAEA.143836

Bedding dips in the CRP-2A drillhole were determined in two ways (1) analysis of a dipmeter log, and (2) identification of bed boundaries on digital images of the outer core surface. The two methods document the downhole increase in structural dip, to a maximum of 15° in the lowest 150 m of the hole. Dipmeter data, which are azimuthally oriented, indicate a 75° azimuth for structural tilting, in agreement with seismic reflection profiles. Core and log dips indicate that structural dip increases by 5-7° between 325 and 480 mbsf. Both, however, also exhibit high dip inhomogeneity because of depositional (e.g., cross bedding) and post-depositional (e.g., softsediment deformation) processes. This variability adds ambiguity to the search for angular unconformities within the CRP-2A drillhole. Dip directions of different lithologies are generally similar, as are dip directions for the four kinds of systems tracts. Downdip azimuths of sands and muds are slightly different from those of diamicts, possibly reflecting the divergence between ENE offshore dip and ESE glacial advance.