--> Constraints on Carbonate Platform Geometry as it Relates to the Fabric of the Upper Slope

AAPG ACE 2018

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Constraints on Carbonate Platform Geometry as it Relates to the Fabric of the Upper Slope

Abstract

Carbonate platforms have been deposited throughout the Phanerozoic and in a variety of tectonic settings. Despite decades of study, the controls on overall platform geometry remain incompletely understood. One key outstanding area of uncertainty is how sediment fabric in the upper slope does or does not influence slope angle. Prior work has concentrated on the relationship of the greatest angle of the upper slope and its fabric. However, one practical issue during data collection is that the greatest slope angle from outcrop or subsurface could be eroded away or not well-exposed. In this study, 26 individual platforms, (25 outcrops and 1 subsurface analog), were analyzed spanning the Devonian to the Quaternary. From each identifiable slope profile, we collected multiple slope angles in the upper slope regime (the upper two-thirds of the slope profile) in order to quantitatively assess the correlation between upper slope angle and several potential correlates: dominant sediment fabric, platform height, geologic age, and tectonic setting. Annotated images of the cross-sections were analyzed using ImageJ software to determine the height of the platform and the angles of the upper slope. The carbonate factory, tectonic setting, dominant fabric of the slope, and geologic age were collected from the source material. Measuring multiple slope angles for each profile provided an opportunity to calculate an average slope angle and determine its significance to the correlates. Similar to results from previous studies, the steepest angle exhibits a statistically significant correlation with the dominant upper slope fabrics and texture. In addition, upper slope fabric is significantly correlated with the average slope angle, indicating that upper slope angle in general is associated with sediment fabric. These findings highlight the potential for slope fabrics to be inferred for subsurface systems in which only the slope angle is known.