10.1594/PANGAEA.50032
Breitzke, Monika
Monika
Breitzke
0000-0002-4868-3141
Grobe, Hannes
Hannes
Grobe
0000-0002-4133-2218
Kuhn, Gerhard
Gerhard
Kuhn
0000-0001-6069-7485
Müller, Peter J
Peter J
Müller
Grain size analysis of sediment core GeoB1510-2
PANGAEA - Data Publisher for Earth & Environmental Science
1996
DEPTH, sediment/rock
Sand
Silt
Size fraction < 0.002 mm, > 9 phi, clay
Sand, mass tara
Sand, mass brutto
Sand, mass netto
Silt, mass tara
Silt, mass brutto
Silt, mass netto
Clay, mass tara
Clay, mass brutto
Clay, mass netto
Grain size, sieving/settling tube
M16/2
Meteor (1986)
Geosciences, University of Bremen (GeoB)
1991-05-07T00:00:00
en
Dataset
10.1594/PANGAEA.735028
urn:nbn:de:gbv:46-ep000102273
10.1029/96JB01891
1248 data points
text/tab-separated-values
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
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 (-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 = kF. 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 -700 dB/m at 400 kHz and a power of n=1-2 in coarse-grained sands to few decibels per meter and n :s; 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.
-36.511
4.72333333333333
Brazil Basin