Petrophysical investigations on sediment core CRP-2A from the Ross Sea, Antarctica, supplement to: Brink, Jason; Jarrard, Richard D (2000): Petrophysics of core plugs from CRP-2A drillhole, Victoria Land Basin, Antarctica. Terra Antartica, 7(3), 231-240

• Main Authors: Brink, Jason, Jarrard, Richard D
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2000
• Subjects: Core wireline system; CRP-2; Sampling/drilling from ice; Cape Roberts Project CRP; Cape Roberts; Ross Sea; Victoria Land; Antarc*; Antarctica; antartic*
• Online Access: https://dx.doi.org/10.1594/pangaea.510751; https://doi.pangaea.de/10.1594/PANGAEA.510751

A suite of petropysical measurements - velocity versus pressure, bulk density, porosity, matrix density, and magnetic susceptibility -was undertaken on 63 core plugs from CRP-2A. These data are used to calibrate neutron, resistivity, and magnetic susceptibility well logs. Agreement between core-plug magnetic susceptibility measurements and both well-log and whole-core data is excellent. Comparison of core-plug bulk densities with continious well-log density records shows very good agreement. Core-plug measurements of matrix density permit conversion of the well-log and whole-core density records to porosity. Sands and muds exhibit similar downhole compaction patterns, and both patterns are consistent with 250 ± 150 m of exhumation. Pervasive cementation, particularly in the lower half of the core, has affected many CRP-2A petrophysical parameters:(1) fractional porosities are reduced by about 0.05 - 0.10 in the lower part of the hole;(2) velocity and porosity rebound are much smaller than is usually observed for unconsolidated sediments with burial depths similar to CRP-2A;(3) velocities are unusually insensitive to pressure, suggesting that any exhumation-induced microcracks have been scaled subsequently;(4) the velocity/porosity relationship lacks the characteristic signature of exhumation-induced microcracks;(5) the velocity/porosity relationship changes with depth, indicating downhole increase in consolidation;(6) Vp/Vs ratios of the highest-porosity sediments are unusually low, implying enhancement of framework stiffness.