Geophysical data acquisition - OGS

Physical properties of sediment cores
from the Antarctic continental margins
M. BUSETTI
Antarctic paleoclimate and paleoenvironmental studies have a key role in the
understanding of the global climate changing. Waxing and waning dynamic of the
Antarctic ice coverage is the most important effect at high latitudes as response to
climatic variations. As sediment deposited on the continental shelf and rise record
the ice fluctuations, they are an essential task in the paleoclimate study. Analysing
the acoustical and physical properties of sediment cores it is possible to investigate
glacial and interglacial stages. P-wave velocity, bulk density and magnetic
susceptibility are closely related to sediment composition and may reflect changes
in grain-size distribution or in the ratio of terrigenous (quartz and clay) and
biogenic components. Generally terrigenous sediment characterise glacial
deposits, while biogenic material is present in the interglacial deposits.
Acoustical and physical property logs of a marine piston core collected on the
continental rise of the Antarctic margin. P-wave velocity and bulk density reflect
the grain size distribution: the higher values in the upper part of the core are
related to silt, and even greater to sand, the lower values in the deeper part
of the core are related to the clay fraction. Ice rafted debris (black spots in the
visual log) produce clear spikes in the magnetic susceptibility measurements.
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