3D Facies
Architecture of a Dryland Shadow Bar, Umbum Creek,
Payenberg, Tobias1, Nathan P. Gardiner1, Carmen
B.E. Krapf1, Mark R. W. Reilly2
(1) The
Modern depositional analogues that
quantify the distribution of facies types create essential data sets that aid
in the development of reservoir models for comparable ancient subsurface
deposits. Umbum Creek flows into the western side of
A high resolution 30x30 m GPR 3D grid was
acquired with a Mala X3M system with 250 MHz antenna across one of the shadow
bars to investigate their 3D internal facies architecture. In addition, several
trenches aligned to the GPS survey lines were excavated to allow a direct
comparison with the interpreted GPR data. The internal facies architecture is
characterized by multiple erosional surfaces, several discontinuous 0.5 to 5 cm
thick mud drapes and fining upward cross-bedded sandy gravel packages. Former
scour pools, imaged as “smilies” in the GPR data set, are filled with
fine-grained sand comprising abundant climbing ripples, sinusoidal ripples and
convex upwards parallel stratification (CUPS), mantled
by mudcracked silts indicating waning flood deposits.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California