, Auditorium
The Cheve karst system, in Oaxaca, Mexico, is one of the deepest karst systems in the world, with a proven depth potential of nearly 2,600 m. Despite the global significance of the Cheve karst system, it has seen relatively little geological study. Recent geological mapping has provided important context for the structural and stratigraphic setting. Here we combine this new information with geological and geomorphological observations we collected across the system since 2009.
The Cheve karst is located in the SE continuation of the Mexican Fold Thrust Belt and has undergone a complex set of tectonic deformations. Initial compressive deformation began during the Late Cretaceous to Paleogene, leading to thin-skinned fold and thrust deformation. This was followed by a period of strike-slip faulting in Eocene-Oligocene time, and a final stage of normal faulting. The cave passages are developed within folded and thrusted carbonate sequences of Upper Cretaceous rocks, located between the metamorphic rocks of the Sierra de Juárez and Mazateco Complexes.
Many faults exhibit reactivation subparallel to the regional NW-SE Oaxaca Normal Fault. In general, we find that cave passages preferentially developed along fracture and fault orientations associated with transtensional stresses. The current terminus of Cheve is along a NE-SW dextral strike-slip fault, which produced a hydraulic barrier to cave development and drove paleoflow in phreatic lift tubes to the NE, perpendicular to the primary orientation of cave development. These passages carried water up several hundred meters above the current low point of Sistema Cheve.
Rogelio Hernández-Vergara, Matthew D. Covington,
Alberto Vásquez-Serrano