Data Description

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Citation:
Brink, J; Jarrard, RD (2000): Petrophysical investigations on sediment core CRP-2A from the Ross Sea, Antarctica. doi:10.1594/PANGAEA.510751,
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, hdl:10013/epic.28278.d001
Abstract:
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.
Project(s):
Coverage:
Latitude: -77.005980 * Longitude: 163.719450
Date/Time Start: 1998-10-16T07:30:00 * Date/Time End: 1998-11-25T14:20:00
Event(s):
CRP-2A (14.2 km at 096° true from Cape Roberts) * * Latitude: -77.005980 * Longitude: 163.719450 * Date/Time Start: 1998-10-16T07:30:00 * Date/Time End: 1998-11-25T14:20:00 * Elevation: -177.9 m * Recovery: 624.00 m * Location: off Cape Roberts, Ross Sea, Antarctica * * Campaign: CRP-2 * * Basis: Sampling/drilling from ice * * Device: Core wireline system * * Comment: 921 m at 284° from CRP-1. Sea-ice thickness: 2.0 m (1 Oct) to 2.2 m (23 Nov). Sea riser embedded to 13.03 mbsf. Lateral ice movement: 9.87 m to east from 17 Oct to 23 Nov. HQ core to 199.31 mbsf. NQ core to 624.15 mbsf. 13.03 to 45.97 mbsf, 11.29 m (34%) partially following CRP-2. 45.07 to 624.15 mbsf, 548.67 m (95%) new hole. Deepest core-lithology: hard sandy siltstone. Deepest core-age: earliest Oligocene (ca. 33 Ma on diatoms, nannofossils and dinoflagellates)
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