Cracking the
Hourglass – Understanding the Fundamental Unit of the Source and Sink
Thurmond, John1, Ole Martinsen1,
Tor Sømme2, William Helland-Hansen2 (1) Hydro Oil and
Energy Research Center, Bergen, Norway (2) University of Bergen, N-5007 Bergen
The next generation of coherent
sedimentary models is complete source-to-sink models, illustrating the entire
distributary-tributary system in plan view, and their segmented cross-sectional
shapes and erosional-depositional profiles. In order to approach a state where
reliable, predictive models can be generated, comparison of source-to-sink
systems from various geological settings must be collected to understand the
influence of key processes on these highly variable, gross
tributary-distributary systems.
The shape of a drainage basin, combined
with its offshore depositional area forms a complete geomorphological unit in
the shape of an hourglass in plan view. A database of drainage basins and their
Recent offshore deposits and sinks has been built up, which can be queried for
trends and relationships. Various shapes of the hourglass are presented to
illustrate critical relationships and processes on different margins.
Understanding the fundamental parameters
of the drainage basin, and associating them with the extent of the deposition
resulting from it, obtains predictive relationships about the resulting
deposits based on measurable parameters. This has the potential to predict
offshore sediment volumes based on easily obtainable onshore data, resulting in
improved hydrocarbon exploration in both known and frontier deepwater basins.
By studying the range of values in the Recent systems, the extent that
complicating factors, such as relative sea-level changes, longshore drift,
temporary sediment storage and margin type control the resulting deposits can
be analyzed. Further development allows for extension of these models to paleo
source-to-sink systems, in the cases where their relic features are preserved
in modern landscapes.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California