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Generally, physical properties of marine sediments are good indicators for the composition,
microstructure and environmental conditions
during and after the depositional process. Their
study is of high interdisciplinary interest and
follows various geoscientific objectives.
Physical properties provide a lithological
and geotechnical description of the sediment.
Questions concerning the composition of a depositional regime, slope stability or nature of
seismic reflectors are of particular interest within
this context. Parameters like P- and S-wave velocity and attenuation, elastic moduli, wet bulk
density and porosity contribute to their solution.
As most physical properties can be measured very quickly in contrast to parameters like
carbonate content, grain size distribution or
oxygen isotope ratio, they often serve as proxy
parameters for geological or paleoceanographical processes and changes in the environmental conditions. Basis for this approach are
correlations between different parameters which
allow to derive regression equations of regional
validity. Highly resolved physical properties are
used as input parameters for such equations to
interpolate coarsely sampled geological, geochemical or sedimentological core logs. Examples
are the P-wave velocity, attenuation and wet
bulk density as indices for the sand content or
mean grain size and the magnetic susceptibility
as an indicator for the carbonate content or
amount of terrigenous components. Additionally, highly resolved physical property core logs
are often used for time series analysis to derive
quaternary stratigraphies by orbital tuning.
In marine geochemistry, physical parameters
which quantify the amount and distribution of
pore space or indicate alterations due to diagenesis are important. Porosities are necessary to
2
Physical Properties of Marine Sediments
MONIKA BREITZKE
calculate flow rates, permeabilities describe how
easy a fluid flows through a porous sediment
and increased magnetic susceptibilities can be
interpreted by an increased iron content or,
more generally, by a high amount of magnetic
particles within a certain volume.
This high interdisciplinary value of physical
property measurements results from the different effects of changed environmental conditions on sediment structure and composition.
Apart from anthropogeneous influences variations in the environmental conditions result
from climatic changes and tectonic events
which affect the ocean circulation and related
production and deposition of biogenic and
terrigenous components. Enhanced or reduced
current intensities during glacial or interglacial
stages cause winnowing, erosion and redeposition of fine-grained particles and directly
modify the sediment composition. These effects
are subject of sedimentological and paleoceanographical studies. Internal processes like
early diagenesis, newly built authigenic sediments or any other alterations of the solid and
fluid constituents of marine sediments are of
geochemical interest. Gravitational mass transports at continental slopes or turbidites in large
submarine fan systems deposit as coarsegrained chaotic or graded beddings. They can
be identified in high-resolution physical property logs and are often directly correlated with sea
level changes, results valuable for sedimentological, seismic and sequence stratigraphic
investigations. Generally, any changes in the
sediment structure which modify the elastic
properties of the sediment influence the reflection characteristics of the subsurface and can
be imaged by remote sensing seismic or echosounder surveys.
Generally, physical properties of marine sediments are good indicators for the composition,
microstructure and environmental conditions
during and after the depositional process. Their
study is of high interdisciplinary interest and
follows various geoscientific objectives.
Physical properties provide a lithological
and geotechnical description of the sediment.
Questions concerning the composition of a depositional regime, slope stability or nature of
seismic reflectors are of particular interest within
this context. Parameters like P- and S-wave velocity and attenuation, elastic moduli, wet bulk
density and porosity contribute to their solution.
As most physical properties can be measured very quickly in contrast to parameters like
carbonate content, grain size distribution or
oxygen isotope ratio, they often serve as proxy
parameters for geological or paleoceanographical processes and changes in the environmental conditions. Basis for this approach are
correlations between different parameters which
allow to derive regression equations of regional
validity. Highly resolved physical properties are
used as input parameters for such equations to
interpolate coarsely sampled geological, geochemical or sedimentological core logs. Examples
are the P-wave velocity, attenuation and wet
bulk density as indices for the sand content or
mean grain size and the magnetic susceptibility
as an indicator for the carbonate content or
amount of terrigenous components. Additionally, highly resolved physical property core logs
are often used for time series analysis to derive
quaternary stratigraphies by orbital tuning.
In marine geochemistry, physical parameters
which quantify the amount and distribution of
pore space or indicate alterations due to diagenesis are important. Porosities are necessary to
2
Physical Properties of Marine Sediments
MONIKA BREITZKE
calculate flow rates, permeabilities describe how
easy a fluid flows through a porous sediment
and increased magnetic susceptibilities can be
interpreted by an increased iron content or,
more generally, by a high amount of magnetic
particles within a certain volume.
This high interdisciplinary value of physical
property measurements results from the different effects of changed environmental conditions on sediment structure and composition.
Apart from anthropogeneous influences variations in the environmental conditions result
from climatic changes and tectonic events
which affect the ocean circulation and related
production and deposition of biogenic and
terrigenous components. Enhanced or reduced
current intensities during glacial or interglacial
stages cause winnowing, erosion and redeposition of fine-grained particles and directly
modify the sediment composition. These effects
are subject of sedimentological and paleoceanographical studies. Internal processes like
early diagenesis, newly built authigenic sediments or any other alterations of the solid and
fluid constituents of marine sediments are of
geochemical interest. Gravitational mass transports at continental slopes or turbidites in large
submarine fan systems deposit as coarsegrained chaotic or graded beddings. They can
be identified in high-resolution physical property logs and are often directly correlated with sea
level changes, results valuable for sedimentological, seismic and sequence stratigraphic
investigations. Generally, any changes in the
sediment structure which modify the elastic
properties of the sediment influence the reflection characteristics of the subsurface and can
be imaged by remote sensing seismic or echosounder surveys.