Comparison and Correlation of Physical-Property Results from Japan Sea Basin and Rise Sites, Legs 127 and 128

Abstract

A few characteristics dominate the bulk physical properties of the sedimentary and igneous formations recovered in the Japan Sea on ODP Legs 127 and 128. The sediments above the opal-A/opal-CT boundary have high porosities over a large interval, with associated low wet-bulk densities and acoustic velocities; some of the detailed features in the uppermost sediments appear to correlate from site to site. The high porosities and general degree of underconsolidation are typical of sediments rich in biogenic silica. The diagenetic transformation from opal-A to opal-CT has a considerable effect on the sediment physical properties and serves as a widespread seismic and thermal marker horizon. The physical properties above and below the boundary are distinctly different. Finally, the interbedded igneous and sedimentary units give rise to strongly layered reflective sequences. The igneous units are highly altered, and the degree of alteration, as expressed through the loss on ignition, significantly affects the physical properties; the density and velocity are lower when alteration products such as clay or zeolite are present.

Seismic indicators of gas hydrate and associated gas in the Ulleung Basin, East Sea (Japan Sea) and implications of heat flows derived from depths of the bottom-simulating reflector

“…No deep conductivity data are available in the Ulleung Basin, but conductivities, measured at Ocean Drilling Program (ODP) sites (Fig. 1A) in the Yamato and Japan basins (Nobes et al, 1992) are nearly constant at about 1.0 W/m°C to the depths of about 300 m below the seafloor. The BSR-derived heat flows in the study area range from about 65 to over 115 mW/m 2 (Fig.…”

The limited suitability of silica diagenetic boundaries as isothermal markers: Insights from seismic reflection imaging, Offshore Sakhalin, Russian Far East

“…The changes in physical properties, resulting from the conversions, cause an increase in the acoustic impedance at the diagenetic boundaries compared to the surrounding sediments. This gives rise to a seismic reflection that can cover areas of at least 10 4 -10 5 km 2 of sedimentary basins (Nobes et al, 1992b;Davies and Cartwright, 2002;Meadows and Davies, 2007), which can cross-cut inclined stratigraphy (Hein et al, 1978;Davies and Cartwright, 2002). The diagenetic boundaries form normal polarity, high-amplitude seismic reflections.…”

Physical properties and their relationship to sedimentary processes and texture in sediments from mud volcanoes in the Anaximander Mountains (Eastern Mediterranean)

“…The wetbulk density, for example, is related to porosity and grain density, and is partially controlled by grain size (Johnson and Olhoeft, 1984) velocity is controlled by porosity and carbonate and clay content Mienert, 1984;Nobes et al, 1986). Physical properties are also influenced by diagenetic effects, especially by the decrease in porosity with increasing compaction, but also by cementation and carbonate dissolution (Nobes et al, 1992).…”