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Physical properties and sedimentology on core GeoB1510-1

Authors
Publisher
PANGAEA
Publication Date
Identifiers
DOI: 10.1594/pangaea.735028
Keywords
  • -
  • <2 µM
  • >9 Phi
  • 20°
  • 400 Khz
  • 400 Khz Q
  • Alpha
  • Amax [Mv]
  • Average Dev
  • Bartington Ms2C Coil Sensor
  • Brazil Basin
  • Caco3
  • Calcium Carbonate
  • Clay
  • Clay
  • Mass Brutto
  • Clay
  • Mass Netto
  • Clay
  • Mass Tara
  • Clay Brutto
  • Clay Tara
  • Density
  • Wet Bulk
  • Dev
  • Deviation
  • F
  • For Breitzke M
  • Fgbremen
  • Formation Factor
  • Geob1510-2
  • Geob2821-1
  • Grain Size
  • Sieving/Settling Tube
  • Gravity Corer (Kiel Type)
  • Kappa
  • Kurt
  • Kurtosis
  • M16/2
  • M29/2
  • Mean
  • Mean
  • Grain Size
  • Mean Gs
  • Meteor (1986)
  • Phi**2
  • Poros
  • Porosity
  • Rio Grande Rise
  • Sand
  • Sand
  • Mass Brutto
  • Sand
  • Mass Netto
  • Sand
  • Mass Tara
  • Sand Brutto
  • Sand Tara
  • Sfb261
  • Silt
  • Silt
  • Mass Brutto
  • Silt
  • Mass Netto
  • Silt
  • Mass Tara
  • Silt Brutto
  • Silt Tara
  • Size Fraction < 0
  • 002 Mm
  • > 9 Phi
  • Clay
  • Skew
  • Skewness
  • South Atlantic In Late Quaternary: Reconstruction Of Budget And Currents
  • Standard Dev
  • Susceptibility
  • Volume
  • Var
  • Variance
  • Velocity
  • Compressional
  • Amplitude
  • Velocity
  • Compressional
  • Attenuation Coeficient
  • Velocity
  • Compressional Wave
  • Vp
  • Vp-A
  • Wbd
Disciplines
  • Earth Science

Abstract

Detailed information about the sediment properties and microstructure can be provided through the analysis of digital ultrasonic P wave seismograms recorded automatically during full waveform core logging. The physical parameter which predominantly affects the elastic wave propagation in water-saturated sediments is the P wave attenuation coefficient. The related sedimentological parameter is the grain size distribution. A set of high-resolution ultrasonic transmission seismograms (ca. 50-500 kHz), which indicate downcore variations in the grain size by their signal shape and frequency content, are presented. Layers of coarse-grained foraminiferal ooze can be identified by highly attenuated P waves, whereas almost unattenuated waves are recorded in fine-grained areas of nannofossil ooze. Color-encoded pixel graphics of the seismograms and instantaneous frequencies present full waveform images of the lithology and attenuation. A modified spectral difference method is introduced to determine the attenuation coefficient and its power law a = kfn. Applied to synthetic seismograms derived using a "constant Q" model, even low attenuation coefficients can be quantified. A downcore analysis gives an attenuation log which ranges from ca. 700 dB/m at 400 kHz and a power of n = 1-2 in coarse-grained sands to few decibels per meter and n ? 0.5 in fine-grained clays. A least squares fit of a second degree polynomial describes the mutual relationship between the mean grain size and the attenuation coefficient. When it is used to predict the mean grain size, an almost perfect coincidence with the values derived from sedimentological measurements is achieved.

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