The Effects of Relative Sea Level, Sediment Supply, and Transport Mechanisms on the Coastal Geomorphology of Carbonate Platforms

Abstract

Carbonate platforms exhibit a broad array of depositional environments that create significant heterogeneity within both modern environments and potential carbonate reservoirs. My research will apply a physical sedimentology approach to understanding the sediment transport and deposition of two volumetrically significant coastal landforms on a modern carbonate platform. The transport from nearshore sediment supply to storage in terrestrial landforms remains a critical component of understanding sediment dynamics in carbonate environments. Two preserved Holocene age landforms, aeolianites and strand plains, along the coast of San Salvador suggest there have been protracted periods of construction of coastal topography during the relative sea level (RSL) rise since the Last Glacial Maximum. These constructional sedimentary features suggest high sediment supply and production from the shallow marine environment throughout the transgression. However, the processes and paleo-environmental conditions required to build dunes and strand plains differ. This work will investigate the coupling of autogenic carbonate sediment production, RSL rise, and platform flooding, along with broader climate shifts (e.g. wind, vegetation) which lead to variable morphologic response. I will use quantitative analysis of high resolution topographic data, sedimentology and radiocarbon dating, and numerical models to explore the timing, magnitude of sediment supply, and transport conditions required to build the preserved coastal landscape. Two open-source numerical models developed by Swanson et al. (2016) and Ashton et al. (2001) will be applied to reconstruct aeolian dune stratigraphy and shoreline evolution, respectively. The models will be used in an exploratory manner to test the hypothesis that the shift in the development of early-Holocene aeolianites to late-Holocene strand plains is controlled by changes in the climate forcing, rather than sediment supply, and indicates a transition from wind-dominated to wave-dominated transport on the platform. Increased understanding of the transport processes and controls on the construction of distinct coastal landforms has significant potential to assist exploration efforts in the context of modeling depositional settings, subsurface mapping, fluid pathways, and characterization of reservoirs analogous to existing fields.

AAPG Datapages/Search and Discovery Article #90351 © 2019 AAPG Foundation 2019 Grants-in-Aid Projects