The influence of biogenic silica on seismic lithostratigraphy at ODP Sites 642 and 643, eastern Norwegian Sea

Drilling at ODP Sites 642 and 643 revealed a 250 m-thick section of diatomaceous Pliocene to Miocene sediments on the outer Vdring Plateau, eastern Norwegian Sea. These biogenic silica-rich sediments have a significantly lower saturated bulk density than the surrounding sediments, causing a decrease...

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Bibliographic Details
Main Authors: Hempel, Peter, Mayer, Larry A., Taylor, Elliot, Bohrmann, Gerhard, Pittenger, Alan
Format: Text
Language:unknown
Published: University of New Hampshire Scholars' Repository 1989
Subjects:
12 Stratigraphy
Historical Geology and Paleoecology
20 Geophysics
Applied Arctic Ocean
biogenic processes
bulk density
Cenozoic
clastic rocks
diatomaceous earth
geophysical methods
geophysical surveys
impedance
Leg 104
lithostratigraphy
marine geology
neutron methods
Norwegian Sea
Ocean Drilling Program
oceanography
ODP Site 642
ODP Site 643
porosity
sedimentary rocks
seismic methods
seismograms
silica
stratigraphy
surveys
synthetic seismograms
Geology
Oceanography and Atmospheric Sciences and Meteorology
Arctic
Arctic Ocean
Online Access:https://scholars.unh.edu/ccom_affil/48
https://scholars.unh.edu/cgi/viewcontent.cgi?article=1047&context=ccom_affil
Description
Summary:Drilling at ODP Sites 642 and 643 revealed a 250 m-thick section of diatomaceous Pliocene to Miocene sediments on the outer Vdring Plateau, eastern Norwegian Sea. These biogenic silica-rich sediments have a significantly lower saturated bulk density than the surrounding sediments, causing a decrease in acoustic impedance, which is seismically expressed as a negative polarity reflection. Variations in sonic velocity, the other key parameter in seismic analysis, is only of secondary importance in creating impedance contrasts in our study. Synthetic seismograms were produced from shipboard physical property measurements corrected for in situ conditions. These synthetic seismograms are in good agreement (< 6 m) with high-resolution air-gun seismic profiles shot during extensive seismic surveys on the Vdring Plateau and provide the basis for correlations between the seismic record and the borehole. The ability to unambiguously identify seismic horizons associated with biogenic silica deposits on the Vdring Plateau will permit the mapping of Miocene productivity patterns.

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