(Table 1) Compressional- and share-wave velocieties at elevated confining pressure of ODP Holes 136-842C and 136-843A


Autoria(s): Wilkens, Roy H; Christensen, Nikolas I; Collins, John A
Cobertura

MEDIAN LATITUDE: 19.339000 * MEDIAN LONGITUDE: -159.092000 * SOUTH-BOUND LATITUDE: 19.336000 * WEST-BOUND LONGITUDE: -159.095000 * NORTH-BOUND LATITUDE: 19.342000 * EAST-BOUND LONGITUDE: -159.089000 * DATE/TIME START: 1991-03-05T20:00:00 * DATE/TIME END: 1991-03-08T22:00:00 * MINIMUM ELEVATION: -4441.0 m * MAXIMUM ELEVATION: -4423.0 m

Data(s)

10/01/1993

Resumo

Identification of a sediment/basement contact using seismic reflection recordings has proven to be extremely difficult in wide areas of the North Pacific Ocean owing to the presence of massive, highly reflective chert layers within the sediment column. Leg 136 of the Ocean Drilling Program recovered coherent pieces of chert of sufficient size for the first comprehensive laboratory measurements of the seismic properties of this material. Compressional-wave velocities of six samples at 40-MPa confining pressure averaged 5.33 km/s, whereas shear-wave velocities at the same pressure averaged 3.48 km/s. Velocities were independent of porosity, which ranged from 5% to 13%, suggesting that pores within the samples were mostly high aspect ratio vugs as opposed to low aspect ratio cracks. Back-scattered electron images made with a scanning electron microscope confirmed this observation. Acoustic impedances were calculated for the chert samples and from shipboard measurements of the red clay sediment overlying the chert layers. An extremely large compressional-wave reflection coefficient (0.73) characterized the interface between the two lithologies. A synthetic seismogram was calculated using chert and typical pelagic carbonate properties to illustrate the influence of chert layers on a marine seismic-reflection section. Compressional-wave to shear-wave velocity ratios of the chert samples (Vp/Vs =1.53) are close to that of single-crystal quartz in spite of variable porosity. Shear-wave reflection coefficients are estimated to be approximately 0.94. A compressional-wave reflection coefficient for a basement/sediment (carbonate) interface is estimated to be approximately 0.50, significantly less than that of sediment/chert.

Formato

text/tab-separated-values, 132 data points

Identificador

https://doi.pangaea.de/10.1594/PANGAEA.805006

doi:10.1594/PANGAEA.805006

Idioma(s)

en

Publicador

PANGAEA

Direitos

CC-BY: Creative Commons Attribution 3.0 Unported

Access constraints: unrestricted

Fonte

Supplement to: Wilkens, Roy H; Christensen, Nikolas I; Collins, John A (1993): Seismic properties and reflectivity of North Pacific Ocean cherts. In: Wilkens, RH; Firth, J; Bender, J; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 136, 99-104, doi:10.2973/odp.proc.sr.136.210.1993

Palavras-Chave #136-842C; 136-843A; Density, wet bulk; DRILL; Drilling/drill rig; Event label; Joides Resolution; Leg136; North Pacific Ocean; Ocean Drilling Program; ODP; ODP sample designation; Sample code/label; Velocity, compressional wave; Velocity, shear wave
Tipo

Dataset