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The sedimentary architecture and spatial variations of dryland ephemeral fluvial systems

Priddy, Charlotte Louise

The sedimentary architecture and spatial variations of dryland ephemeral fluvial systems Thumbnail


Authors

Charlotte Louise Priddy



Contributors

Stuart Clarke
Supervisor

Abstract

Ancient dryland continental basins commonly comprise sedimentary fill that records the activity of both fluvial and aeolian environments. Despite extensive studies of dryland ephemeral fluvial systems, detailed three dimensional facies models for these systems are appreciably fewer in number and are less developed compared to those of their meandering and braided fluvial counterparts. This is despite the fact that depositional models illustrate the arrangement and interactions between depositional elements, along with the vertical and lateral connectivity of those elements, which are particularly useful and important for reservoir characterisation.
This work focusses on an extensive outcrop analogue study of the dryland fluvial Kayenta Formation of the Colorado Plateau, USA, and applies the findings to a detailed core study of the Leman Sandstone, a similar depositional setting within the subsurface of the Southern North Sea, UK. The work utilises extensive regional fieldwork to examine the sedimentology, geometries, and interactions of ephemeral fluvial and aeolian environments, along with analysis of the spatial and temporal variations across the depositional system.
Results show that the Kayenta ephemeral fluvial system is dominated by sandy laterally and vertically amalgamated, poorly channelised to sheet-like elements, with abundant upper flow regime structures. Spatial analysis of the system indicates many trends that are similar to those of a dryland terminal fluvial system, whereas temporal analysis indicates an overall regression of the fluvial system through time.
This study provides valuable sedimentological data for characterising dryland fluvial systems, particularly when analysing the spatial and temporal variations of the system and demonstrates the inherent complexity in dryland fluvial systems and the downstream architectural and compositional relationships that they depict. These results are used to reconstruct the Leman Sandstone, providing valuable three dimensional data, in order to better characterise basin scale migration and reservoir quality.

Thesis Type Thesis
Publicly Available Date Mar 29, 2024
Award Date 2021-10

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