| Popis: |
The deep core samples (site name: 21ESDP-203, drilled depth: 200.3m) collected from the southeastern shelf (Korea strait) of Korea were used to characterize physical property with sedimentary depth. Laboratory analysis (i.e., velocity and physical properties) was conducted on core samples. The physical property data were readily classified in good agreement with the lithological units alternating sandy mud and muddy sand with sedimentary depth. Based on compressional wave velocity data, the geoacoustic units are divided by 11 units with sedimentary depth. In particular, the upper sediments above 15 meter are characterized by high compressional wave velocity (greater than 1700 m/s) and high wet bulk density (∼2.2g/cm3 in maximum). Whereas, the porosity is very low (25% in minimum). This is due to the abundance of sandy sediments in this interval. The shear wave velocities of sediments are calculated from the compressional wave velocity and the effect of burial depth (Hamilton, 1980). The range of shear wave velocity is from 267 to 1345 m/s. However, most of data are less than 400 m/s. The velocity ratio (Vp/Vs) and the velocity gradient with sedimentary depth are calculated and estimated. The patterns are slightly different from those of Hamilton (1980). These results suggest that the physical properties are not only controlled by lithology and compaction caused by dewatering with burial depth, but also by different sedimentary environment after deposition. |
