Flank margin caves as proxies for the evolution of Cozumel Island, Mexico

Abstract

There has been a recent increase in research on coastal karst, revealing numerous morphologies connected to the relative sea-level position. In particular, the flank margin caves are recognized as excellent markers of ancient sea-level changes and paleo-coast lines. Here, we characterized the Cozumel flank margin caves using cave morphology and morphometry, surface terrace maps, and host rock microfacies. The Cozumel flank margin caves exhibit three main morphologies: classic, multiphase, and banana hole. Microfacies analysis reveals that classical and multiphase flank margin caves morphologies evolved in rocks formed in a protected lagoon environment. In contrast, banana hole morphologies developed in rocks belonging to a margin platform and sand shoal environment. Morphometric values reveal high erosion or diagenetic overprint, particularly in banana hole morphologies. The distribution of flank margin caves in Cozumel, located on terraces II and III, is closely linked to the last highstand sea level MIS 5e, indicating the past sea-level position and revealing changes in the island landscape, starting as a cluster of small sandy islands merging into a single island subsequently. The development of Cozumel flank margin caves and sedimentary units is comparable to other carbonate islands. However, differences in the size of Cozumel flank margin caves compared to The Bahamas analogs open a new window to additional studies about the time needed for cave development.