Physical Properties of the AND-2A Core, ANDRILL Southern McMurdo Sound Project, Antarctica

Authors

Gavin B. Dunbar, University of Wellington, New ZealandFollow
C. Atkins, Victoria University of Wellington
D. Magens, Alfred Wegener Institute for Polar and Marine Research
F. Niessen, Alfred Wegener Institute for Polar and Marine Research
ANDRILL-SMS Science Team

Date of this Version

2008

Comments

Published in Terra Antartica 2008-2009, 15(1), 49-56. © Terra Antartica Publication 2008-2009.

Abstract

Whole-core measurements of Wet Bulk Density (WBD), compressional (P)-wave velocity (Vp), and Magnetic Susceptibility were measured at a sampling interval of 1 or 2 centimetres (cm) throughout the AND-2A drill core for initial core characterisation and on-site correlation with seismic modeling to predict target-reflector depth. Measurements were made using a GEOTEK (Multi-Sensor-Core-Logger MSCL). Density and velocity standards were measured together with core runs of 3-6 metres (m) (and occasionally up to 18 m) throughout the entire depth range to monitor data quality. Drift of the magnetic susceptibility sensor was also monitored and corrected where necessary. These physical properties show a large range of values, reflecting the different nature of the various lithologies including extremely high velocity and density values in individual clasts, and the effects of cementation on porosity. A downcore increase in WBD and Vp occurs in the upper 200 m, however, no systematic trend exists at greater depths although large fluctuations on a m-decimetre- (dm) scale occur. Magnetic susceptibility is generally low (<100 x>10^-5 SI), however, four intervals of high (>600 x 10^-5 SI) susceptibility occur at 560, 800, 980 and 1 080 mbsf, indicating a relatively greater contribution of volcanic-derived material to the core site in the lower half of the AND-2A core.