Stratigraphic variability along windward and leeward slopes of an isolated carbonate platform, Cretaceous of central Mexico

Carbonate slopes record complex and often chaotic depositional patterns shaped by both intrinsic, sediment–gravity-driven processes and broader extrinsic controls acting on the platform system. Delineating the architecture produced by these influences is challenging; however, isolated platforms offer valuable insight by preserving contrasting windward and leeward slope successions.

The Cretaceous Tamabra Formation exposed along the El Doctor Platform in central Mexico offers an excellent opportunity to examine these contrasts using extensive strike-parallel outcrops. This study integrates detailed field observations, measured sections totaling over 3 km, high-resolution photomosaics, and UAV-based 3D models.

Five deep-water facies are recognized within the Tamabra Formation, representing a range of resedimented carbonate deposits derived from both platform and basin environments. The windward slope records a clear multi-stage evolution tied to changes on the adjacent platform during the Albian. Early deposition was dominated by fine-grained turbidites and background mudstone sedimentation, followed by increased slope instability and debrite emplacement. A subsequent interval reflects reduced sediment supply, after which prolonged coarse-grained shedding produced a grain-rich slope apron. The final stage is marked by widespread mass wasting and a return to mud-dominated conditions.

In contrast, the leeward slope shows no consistent long-term evolution. It is thicker than the windward margin and characterized by continuous, line-fed sedimentation consisting of grainstone sheets, turbidites, and relatively small, confined debrites, with minimal channel development.

These architectural differences suggest fundamentally different sediment routing systems on either side of the platform. Windward slopes appear more sensitive to base-level changes, whereas leeward slopes reflect steady sediment export driven by persistent trade winds. Similar asymmetry observed in isolated carbonate platforms worldwide highlights the importance of internal platform dynamics in controlling carbonate slope development.