AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Remembering the 'Source' When Applying Source-to-Sink Concepts in Clastic Stratigraphy
(1) Chevron Energy Technology Co., San Ramon, CA.
(2) Chevron Energy Technology Co., Houston, TX.
(3) Chevron Energy Technology Co., Perth, WA, Australia.
Concepts associated with the holistic characterization of sedimentary systems from net-erosional source areas to sites of final deposition (commonly referred to as ‘source-to-sink’) have been discussed for the past decade, but only recently applied to petroleum geology. The appeal of source-to-sink is the potential to develop improved geomorphic and stratigraphic predictive relationships, especially when integrated with traditional methodologies. Although the source-to-sink label is becoming more frequent in published literature, stratigraphic studies documenting facies changes over long distances and across depositional environments within a chronostratigraphic framework should not be called source-to-sink studies because they ignore the source area. Whereas linking fluvial strata to coeval deltaic deposits, or shelfal deposits to deep-marine strata, for example, are valuable from a sequence stratigraphic perspective they are still characterizing only part of the entire sediment-routing system. Knowledge of the sediment source area can provide powerful predictions of sediment supply, staging area relationships, stratigraphic architectures and reservoir quality in the depositional basin.
For Neogene and younger systems, the sediment source area is commonly preserved, at least partially, and available for direct study. The deeper in geologic time the sedimentary system of interest the more likely the source area is removed through denudation and/or tectonic deformation. Adequately addressing the source area for partially preserved sedimentary systems requires: (1) characterizing patterns of composition and age of the material, and (2) leveraging relationships revealed from more complete Quaternary systems in an analog sense. New provenance methodologies, such as coupled geo-/thermochronology of single grains, integrated with established methods can provide information about rates of uplift and exhumation in source areas, which can be used to evaluate type and amount of sediment supplied to depositional sinks. Source-to-sink studies of Quaternary systems, in which morphologic relationships between segments of a complete sediment-routing system can be measured and related to rates of sediment transfer and storage, represent a new class of system-scale analogs. Quantitative and qualitative relationships from such analogs can be used to inform exploration decisions and/or provide numerical constraints to burgeoning forward modeling approaches.