Sound velocity–density relations in sea-floor sediments and rocks

Abstract

In studies in underwater acoustics, geophysics, and geology, the relations between sound velocity and density allow assignment of approximate values of density to sediment and rock layers of the earth's crust and mantle, given a seismic measurement of velocity. In the past, single curves of velocity versus density represented all sediment and rock types. A large amount of recent data from the Deep Sea Drilling Project (DSDP), and reflection and refraction measurements of sound velocity, allow construction of separate velocity-density curves for the principal marine sediment and rock types. The paper uses carefully selected data from laboratory and in situ measurements to present empirical sound velocity-density relations (in the form of regression curves and equations) in terrigenous silt clays, turbidites, and shale, in calcareous materials (sediments, chalk, and limestone), and in siliceous materials (sediments, porcelanite, and theft); a published curve for DSDP basalts is included. Speculative curves are presented for composite sections of basalt and sediments. These velocity-density relations, with seismic measurements of velocity, should be useful in assigning approximate densities to sea-floor sediment and rock layers for studies in marine geophysics, and in forming geoacoustic models of the sea floor for underwater acoustic studies.

Physical and thermal properties of mud-dominant sediment from the Joetsu Basin in the eastern margin of the Japan Sea

“…Several empirical formulae for relationships between two physical properties of marine sediment have been proposed: sound velocity and density (Hamilton 1978), sound velocity and thermal conductivity (Horai 1982), and thermal conductivity and other thermal properties (Von Herzen and Maxwell 1959;Hyndman et al 1979;Goto and Matsubayashi 2008). Empirical formulae for relationships between thermal properties and the porosity and volume fraction of constituent minerals for marine sediments have also been investigated (Kinoshita 1994;Villinger et al 1994;Goto and Matsubayashi 2009).…”

The spatial extent of the Deep Western Boundary Current into the Bounty Trough: new evidence from parasound sub-bottom profiling

“…However, many analyses of relation between P-wave velocity and density of clastic sediments have shown that P-wave velocity can directly be derived from density via empiric relations (e.g. Erickson and Jarrard 1998;Hamilton 1978;Nafe and Drake 1957). This implies that the velocity shows exactly the same trend as the density and that the density is an adequate proxy for the impedance.…”

Site 800

“…The average of the measurements is 1470 m/s, less than the velocity of sound in seawater. This anomalous situation is not unusual for deep-sea sediments at shallow burial depths (Hamilton, 1974).…”

“…relationships in deep-sea sediments (Hamilton, 1978). Density and velocity data for the dolerites do not define a clear relationship between the two parameters.…”