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Bücker, Christian J; Henrys, Stuart A; Wonik, Thomas (1998): Porosity and sound velocity measured in sediment core CIROS-1. PANGAEA,, Supplement to: Bücker, CJ et al. (1998): Revision of the Cenozoic seismic velocity structure of the CIROS-1 drillhole, Antarctica, and implications for further drilling off Cape Roberts. Terra Antartica, 5(3), 281-289, hdl:10013/epic.28339.d001

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The CIROS-1 drillhole, which in 1986 reached a depth of 700 m below the seafloor, is still the only deep hole that can provide information on the velocity structure of the upper crust in McMurdo Sound and the Ross Sea, Antarctica. A careful review and quality control of the downhole logging data of CIROS-1 resulted in a new porosity depth function that is consistent with porosity data from the MSSTS-1 and CRP-1 drillholes. Using existing porosity-velocity equations, it was possible for the first time to obtain reliable velocity information for the upper 700 m of strata off the Victoria Land coast. The calculated synthetic seismograms, based on downhole velocity and density data, fit very well with the existing seismic lines IT90A-71, PD90-12, and NBP9601-89. The quality of the correlation confirms that the average velocity of the top 700 m of strata is about 2 000-2 300 m/s, and not 2 800-3 000 m/s, as was previously assumed. In consequence, these distinctly lower velocities result in shallower depths for the seismic unconformities V3/V4 andV4/V5 and thus may have important implications for further drilling off Cape Roberts.
Latitude: -77.081872 * Longitude: 164.498860
Date/Time Start: 1986-10-15T00:00:00 * Date/Time End: 1986-11-14T00:00:00
Minimum DEPTH, sediment/rock: 1.50 m * Maximum DEPTH, sediment/rock: 672.00 m
CIROS-1 * Latitude: -77.081872 * Longitude: 164.498860 * Date/Time Start: 1986-10-15T00:00:00 * Date/Time End: 1986-11-14T00:00:00 * Elevation: -197.5 m * Penetration: 702.14 m * Recovery: 660 m * Location: Butter Point * Campaign: CIROS * Basis: Sampling/drilling ice * Method/Device: Drilling/drill rig (DRILL) * Comment: Sea ice thickness 2 m
#NameShort NameUnitPrincipal InvestigatorMethod/DeviceComment
1DEPTH, sediment/rockDepth sedmGeocode
2PorosityPoros% volBücker, Christian JCalculated
3Velocity, compressional waveVpm/sBücker, Christian JCalculated
5366 data points

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