Abstract:
Quantification of limestone petrology and structure in a 25 km² section of the northern Vaca Plateau, Belize, facilitated development of a model of speleogenesis and evolution of area caves and the karst landscape. The limestones in the study area are mostly depositional breccias developed between the mid-Cretaceous and mid-Tertiary adjacent to the emergent Maya Mountain Fault Block. Micritic and some fossiliferous-pelletic lithoclasts of the Cretaceous Campur Formation are cemented by sparite which formed in a shallow-sea high energy environment adjacent to the emergent area. Planes of structural weakness developed in the Campur Limestone have similar orientations to contemporary karst landform features including solution valleys, the long-axis of depressions, and cave passages. This correspondence suggests an important structural control on the formation and evolution of area caves and the karst landscape. Base level modification by way of valley incision and the development of secondary permeability enhanced interfluve development, causing caves to be truncated along valley sides and abandoned as active flow routes. The dry valleys and stair-step cave profiles indicate that the lowering of base level through time was interspersed with stable periods when horizontal cave passages were excavated.