Physical property characterization of the Nakdong River valley sediments in relation to depositional units

Abstract

The core samples collected from the Nakdong River valley area were used to characterize physical properties in relation to depositional units. The physical property data were readily classified in good agreement with the depositional units: Units I, II, III, and IV in ascending order. In other words, the variations in the physical properties reflected well the relative characteristics of the depositional units. Overall, Unit I was characterized by high values of physical properties such as compressional wave velocity (1683 m/s on average), wet bulk density (2.17 g/cm3 on average), and shear strength (41.2 kPa on average), whereas the porosity of Unit I was the lowest (approximately 35%). Moreover, the physical properties other than grain density reflected well the characteristics of each unit, characterized by gradual change from Units I to IV. Nevertheless, based on the physical property data, the lithology, rather than compaction with burial depth, likely played an important role in the variation of physical properties of each unit. These results suggest that the physical properties were mainly controlled by depositional processes at the time of deposition. The velocity anisotropies were mostly negative without a significant effect of compaction with burial depth. Nevertheless, the cracks occurring along bedding planes after coring were responsible for low horizontal velocities and negative anisotropies.