The Evolution of Fluvial Meander Belts and Their Product in the Rock Record
Abstract
Understanding linkages between modern fluvial morphodynamic processes and their products in the rock record enables enhanced paleoenvironmental and stratigraphic interpretations. A significant challenge to interpretations is the disparity in information available from modern environments and ancient outcrop or subsurface data sets. Limited exposure in outcrop belts and widely spaced or low-resolution perspectives in the subsurface make interpretations challenging. In order to address these challenges, a comprehensive series of data sets, including a numerical model of meandering channels, the floodplain of the lower Mississippi River, outcropping deposits of the Horseshoe Canyon Formation, and the subsurface McMurray Formation, have been compiled in order to deduce evolutionary stages and characterize deposits of meander belts. A variety of methods are employed, including outcrop characterization, seismic interpretation, statistical modeling, and paleochannel reconstructions. Novel approaches to quantifying meander-bend accretion directions, and the deposition and preservation histories of meander-belt deposits, are significant contributions of this study. The study provides insight into the controlling processes of preservation, with implications for the “Sadler Effect” and the completeness of the stratigraphic record. Through the integration of a wide range of data sets, the expression of morphodynamic processes that are commonly observed in modern systems is identified in the rock record – these insights are incorporated into geocellular models, for the purpose of optimal reservoir predictions in meanderbelt reservoirs.
At the meander-bend scale, stratigraphic evidence for a series of processes are featured, including: (1) intra-point-bar erosion and rotation; (2) meander-bend limb
migration and the formation of side bars; (3) mid-channel bar deposition; and (4) flow separation around downstream translating bars and the formation of counter-point bars (i.e., concave bank benches). At the meander-belt scale, reconstructed paleochannel migration patterns reveal the evolutionary history of the various deposits studied. Meander-belt deposition and preservation is quantified. The “survivability”, or preservation potential of a meander-belt deposit over time, follows a natural logarithmic function of decay.
Description
Keywords
Geology
Citation
Durkin, P. (2016). The Evolution of Fluvial Meander Belts and Their Product in the Rock Record (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/28141