Understanding End-Member Deltaic Bar Types: Implications for Delta Stratigraphy
Rebecca Caldwell
Geological Sciences, Indiana University, Bloomington, IN, USA
[email protected]
Abstract
Deltaic morphology and stratigraphy result from the interplay of upstream factors derived from the source terrain, and downstream factors from the receiving basin. Deltaic morphology and stratigraphy should thus reflect both domains, making deltaic deposits prime records of past environments. Deltas are composed of lobate sedimentary features referred to as bars, which have many shapes and sizes and likely represent a range of growth processes and stratigraphies. Despite their importance as the fundamental architectural elements constructing deltaic deposits, we know surprisingly little about their different facies and internal sedimentary architectures. In order to distinguish between different delta morphologies in the stratigraphic record, we must first be able to distinguish between different deltaic bar deposits. I hypothesize that morphologically distinct deltaic bars are (1) created by different growth processes, and (2) constructing unique internal sedimentary architectures. To test these ideas, I propose a comparative study of bars with different morphologies found on the elongate Beanblossom Creek delta, USA and the braided Goose River delta, Canada. This study includes quantification of bar growth processes using serial aerial images and characterization of internal sedimentary architectures using ground-penetrating radar tied to sediment cores. The intended result is the development of stratigraphic models for deltaic bars with different end-member morphologies and growth processes. We currently lack such models, which is surprising given the importance of deltaic bars as hydrocarbon reservoirs. The results of this study will aid in prediction of morphologically distinct bars as potential hydrocarbon reservoirs and stratigraphic interpretations of past depositional environments.
AAPG Search and Discovery Article #90199 © 2014 AAPG Foundation 2014 Grants-in-Aid Projects