Preliminiary results and documentation of sediment core CRP-3 from the Ross Sea off Cape Roberts, Antarctica

• Main Authors: Barrett, Peter J, Webb, Peter-Noel, Aghib, Fulvia Sharon, Alberti, Mauro, Anderson, Jo, Askin, R A, Atkins, Cliff, Bohaty, Steven M, Bryce, S M, Bücker, Christian J, Bush, Stewart, Claps, Michele, Curren, Matthew, Fielding, Christopher R, Florindo, Fabio, Galeotti, Simone, Hannah, Mike J, Harris, Adam H, Harwood, David M, Henrys, Stuart A, Jackson, Nick, Janecek, Thomas R, Jarrard, Richard D, Judge, Shelley, Kopsch, Conrad, Krissek, Lawrence A, Laird, M G, Lavelle, Mark, Majewski, Wojciech, Naish, Tim R, Neumann, M, Niessen, Frank, Paterson, Matt, Paulsen, Timothy S, Pompilio, Massimo, Powell, Ross, Pyne, Alexander R, Rafat, Ghodrat, Raine, J Ian, Roberts, Andrew P, Sandroni, Sonja, Sarti, Massimo, Schulze, Peter, Simes, J, Smellie, John L, Smith, Bruce, Sorice, Alfredo, Strong, C Percy, Talarico, Franco M, Taviani, Marco, Thorn, Vanessa C, Verosub, Kenneth Lee, Watkins, David K, Wilson, Gary S, Wilson, Terry, Wise, Sherwood W, Woolfe, Ken, Wrenn, John
• Format: Other/Unknown Material
• Language: English
• Published: PANGAEA 2006
• Subjects: Cape Roberts Project; Core wireline system; CRP; CRP-3; CWS; Ross Sea; Sampling/drilling from ice; Antarc*; Antarctica; Sea ice; Victoria Land
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.548021; https://doi.org/10.1594/PANGAEA.548021

The site for CRP-3, 12 km east of Cape Roberts (77.006°S; 103.719°E)was selecte to overlap the lower Oligocene strata cored in nearby CRP-2/2A, and to sample the oldest strata in the Victoria Land Basin (VLB) for Paleogene climatic and tectonic history. As it transpired there was underlap of the order of 10s of metres. CRP-3 was cored from 3 to 939 mbsf (metres below the sea floor), with a core recovery of 97%. Coring took place from October 9 to November 19, 1999, on 2.0 to 2.2 m of sea ice and through 295 in of water. The Cenozoic strata cored were mostly g1acially influenced marine sediments of early Oligocene age, though they may be earliest Eocene near the base, where at 823 mbsf Devonian Beacon sandstone was encountered. Following CRP-1 and CRP-2/2A, CRP-3 completes the coring of 1500 m of strata on the western margin of the VLB. Core fractures and other physical properties, such as sonic velocity, density and magnetic susceptibility, were measured throughout the core. Down-hole logs for these and other properties were taken from 20 down to 900-919 mbsf. Also, vertical seismic profile data were gathered from shots offset both along strike and up dip from the hole. Sonic velocities in CRP-3 are close to 2.0 km/s in the upper 80 m, but become significantly faster below 95 mbsf, averaging 3.2+0.6 km/s to the bottom of the hole. An exception to this is an interval of dolerite conglomerate from 790 to c. 820 mbsf with a velocity of c. 4.5 km/s. Dip of the strata also increases down-hole from 10° in the upper 100 m to around 22° at the bottom. Over 3000 fractures were logged through the hole, and borehole televiewer imagery was obtained for most of the hole for orienting core and future stress field analysis. Two high-angle crush zones, interpreted as faults, were encountered at c. 260 and c. 540 mbsf, but no stratigraphic displacement could be recognised. A third fault zone is inferred from a low angle shear zone in the upper part of a coarse dolerite conglomerate from 790 to 805 mbsf. Temperature gradient was ...