Elements of Marine Geology - TU Delft OCW · 2016. 2. 9. · Elements of Marine Geology Delft...
Transcript of Elements of Marine Geology - TU Delft OCW · 2016. 2. 9. · Elements of Marine Geology Delft...
Vermelding onderdeel organisatie
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Elements of Marine Geology
Delft Institute of Earth Observation and Space Systems
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Bathymetry of the Earthan overview
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Topography of the seafloorfeatures 1
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Topography of the seafloorfeatures 2
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A typical ocean bottom sectiontypical sound speed values
Sedimentary rock
Oceanic crust (basalt)
Unconsolidated sediments
ScatteringReflection
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Stratification of sediments
Recent sediments:stratification parallel tothe seabed
Older sediments:deformation
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Geo-acoustic modelling of the seafloor
P- and S- waves
(sound) (only solids)
A geo-acoustic model of the seafloor comprises the following parameters
- compressional (P-) wave speed- shear (S-) speed- compressional wave attenuation- shear wave attenuation- density
as a function of depth.
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Sedimentsunconsolidated rock and mineral particles
• Clastic sediment (loose rock fragment and mineral grains)
• Chemical sediment (precipitation of dissolved matter)• Biogenic sediment (fossil remains of organisms)
> 2mm
0.06 - 2 mm
0.004 - 0.06 mm
< 0.004 mm
= mudstone
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Rocksnaturally formed, coherent aggregate of
minerals
• Igneous rocks, formed by cooling and consolidation of magma(examples: granite, basalt)
• Sedimentary rocks, formed by cementation of sediment• clastic (examples: sandstone, siltstone, conglomerate)• chemical (evaporites)• biogenic (limestone, consisting mainly of the mineral calcite)
• Metamorphic rock (high temperature, high pressure)
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Geo-acoustic parameters of sediments
Shepard diagram
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Geo-acoustic parameters of sediments
grain size, porosity, density, sound speed
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Geo-acoustic parameters of rocks
Compressionalspeed [m/s]
Shear speed[m/s]
Density [g/cm3]
Igneous rocks Granite 6000 3500 2.65Basalt 4800 2500 2.5
Sedimentaryrocks
Sandstone 4700 2700 2.5
Siltstone 3800 2150 2.4Mudstone 2200 1000 2.2Limestone 6000 3000 2.65