Linking
Sedimentology and GPR Data: the Subsurface Holocene of
Fürstenau, Jörn1, Sebastian
Lindhorst1, H. Christian Hass2, Susanne Feindt1,
Christian Betzler1 (1)
Sylt is a barrier island close to the
German North Sea coast. In this study we link ground penetrating radar (GPR)
and sedimentological data to reconstruct the Holocene development of the
northern barrier spit. Present outcomes of the studies let us determine a
distinct correlation of radar facies and lithofacies.
GPR data allow high-resolution
investigation of the shallow subsurface. A GSSI
SIR-3000 radar, either coupled with a 100 MHz or a 200 MHz antenna, was used. A
penetration depth of 350-500 ns TWT is achieved which corresponds to
approximate depths of 10-15 m. Refining GPR raw data in an appropriate
processing flow which includes 1D- and 2D-filter, migration, deconvolution and
gain, as well as topographic correction using ReflexW enhances quality and thus
data interpretability. Different configurations of reflector amplitude, shape,
orientation, continuity and termination type can be
distinguished and separated as numerous radar facies types in the depositional
succession of the spit system.
Lithofacies logs obtained from cores
retrieved along the GPR lines and laser-diffraction grain size analysis serve
as a key to deduce a genetic stratigraphic model from the GPR data. Linking
energy regime distribution and evidence of transport mechanism to radar facies,
distinct sedimentary environments can be reconstructed.
Correlation of lithological and GPR data
reveal that high amplitude reflections are related to sudden change in grain
size. Based on variations in grain size and sorting, porosity changes in the
sediment can be derived. Correlation of distinct porosity intervals with radar
facies therefore allows to propose a model of the
subsurface porosity distribution.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California