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Stratigraphic Architecture and Sediment Partitioning in the Mixed Carbonate-Siliciclastic Bone Spring Formation, Delaware Basin, Texas


Slope-building processes and sediment partitioning in mixed carbonate-siliciclastic sediment routing systems are poorly understood but are important constraints on the spatial and temporal distribution of reservoir-forming elements. The Bone Spring Formation of the Delaware Basin in west Texas is a mixed carbonate and clastic system that acts as a prolific hydrocarbon reservoir. The Bone Spring Formation consists of cyclic shelf-to-basin deposits of sandy turbidites to carbonate turbidites and mass-transport deposits that were sourced from the shelf margin during Leonardian time (~275 Ma). Much research has focused on the distal deposits of the Bone Spring Formation, but there has been little research on the proximal staging area that outcrops in Guadalupe Mountains National Park (GUMO). Our research aims to describe the stratigraphic architecture of the Bone Spring Formation in GUMO in order to delineate the staging area and the dynamics of carbonate and siliciclastic sediment delivery to the basin. Using drone-derived 3D models and measured sections, we document slope-building processes and intermixing of siliciclastic and carbonate lithofacies in the outcropping Bone Spring Formation. Bed orientations and regional surfaces identified several slope-building clinothems that vary from siliciclastic-rich to carbonate-rich and show significant variability in slope propagation direction. These results suggest that the temporal and spatial distribution of siliciclastic-rich lithofacies in the staging area likely impact the stacking patterns of siliciclastic and carbonate lithofacies in the basin. Additionally, the presence of a significant shift in clinothem orientation corresponds to the clinothem containing the highest frequency of failure surfaces and submarine channel deposits, suggesting that entry points of coarse-grained carbonate material to the basin may be related to slope morphology. These results suggest that the dynamics of the upper-slope environment are a primary control on reservoir-forming elements in the basin. Our work provides a better understanding of slope building processes of mixed-lithology clinothems, specifically in steep carbonate margins with periodic siliciclastic input. Our characterization of the outcropping Bone Spring Formation aids in reservoir prediction for future development in the Bone Spring Formation and similar targets in the Delaware and Midland basins like the Spraberry and Wolfcamp Formations.