AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Source to Sink – Why it Matters
(1) ETC, Chevron Energy Technology Company, Houston, TX.
(2) Exploration, Statoil ASA, Bergen, Norway.
(3) Department of Geology and Geophysics, University of Minnesota, Minneapolis, MN.
The recognition that events that happen in one part of a sedimentary basin can strongly influence responses in other parts of that basin lies at the heart of the justification for source-to-sink studies. Conditions in upstream reaches of basins can have profound influence upon process and products observed downstream. Upstream conditions and characteristics can include climate, provenance lithology, and size, shape, available relief, as well as slope gradient of the catchment area. For example, a large relatively low-gradient basin may be dominated by fine-grained sediments delivered to the shoreline and beyond. Shoreline, shelf and gravitational processes as well as morphology on the slope beyond, can be strongly influenced by sediment caliber. In basins dominated by delivery of fine-grained sediments to the deep water, deposition of leveed channels across the slope and basin floor will be favored over deposition of weakly confined channels comprising sheet-like deposits. Larger basins with large rivers associated with long-distance transport of sediments will tend to be characterized by finer-grained sediment loads than smaller basins, where available relief is similar.
Consequently, small basins in active tectonic settings, where available relief is high, can be capable of producing high-volumes of sediment that will tend to be relatively coarser grained than large basins in passive tectonic settings. The style of sedimentation in these two basin types can be radically different. Factors such as climate also can have far-reaching effects. Aspects such as temperature range and precipitation amounts and frequency, can exert a strong influence on factors such as weathering and vegetative cover, which, in turn, can strongly influence sediment discharge and sediment caliber. These factors, coupled with basin shape and morphology can further modulate geologic processes and products.
While the holistic view of geology is implicit in sequence stratigraphic analyses, source-to-sink studies even more-strongly emphasize a combination between stratigraphy and geomorphology. Inherent to source-to-sink analysis is that through the linkage of discrete depositional systems there is a tacit acknowledgement of the interdependence of these systems. A robust appreciation of this linkage can significantly improve understanding of risk and uncertainty with respect to lithology prediction, especially in exploration settings that can greatly benefit from this approach.