Anatomy and depositional systems of Cretaceous isolated carbonate platforms of the western Gulf of Mexico

Carbonate platform systems reached a global acme during the Cretaceous, occupying shallow shelves throughout the Gulf of Mexico and recording some of the world’s most diverse platform systems. Most of our understanding of these systems stems from land-attached platforms in the northern Gulf of Mexico resulting in detailed assessments of their depositional systems. Isolated platforms in the region, however, have received less attention even though they display significant variations in their architecture, faunal makeup, and depositional histories. This study utilizes a comprehensive field-based data set collected from the well-exposed isolated Cretaceous El Doctor platform in central Mexico to characterize the platform’s 3-D shelf-to-basin depositional systems and stratigraphic architecture. Results from this study include 10 facies associations defined across El Doctor, covering platform-interior, shelf-crest, margin, slope, and basinal environments. These results are summarized in a 3-D genetic depositional model of El Doctor that highlights variable influences of intrinsic (e.g., dominant wind direction) and extrinsic (e.g., underpinning tectonics and paleogeographic position) factors on stratal distribution across the platform. Furthermore, unlike platform margins in the northern Gulf of Mexico, which are composed of coralgal and rudist associations, the El Doctor margins record a paucity of framework-building organisms and are instead dominated by caprinid rudist associations with ubiquitous early marine cement. Despite rudists being non-framework building organisms, they developed steep margins at El Doctor with an estimated shelf-to-basin relief of 700−1000 m, suggesting that early marine cementation likely played a more critical role in the development of the platform margin.