U–Pb calcite dating of brittle deformation in Permian carbonates within the Chicomuselo fold and thrust belt, SE Mexico

Abstract

U–Pb calcite dating is a powerful tool for the analysis of geological processes as calcite cements are ubiquitous and sensitive markers of diagenesis, fluid-rock interaction, fluid-flow, and fracturing. This technique provides the possibility of constraining the timing and history of deformation in diverse tectonic scenarios. We analyze calcite cement from fossil-shells, rock-matrix, and tectonic veins emplaced in shortened Permian limestone layers of the Chicomuselo fold-thrust belt (CFTB) in southeastern Mexico. We report 99 insitu U–Pb calcite ages with high temporal and structural resolution from fold/fault-related veins and from complexly fractured rocks. Samples selected with structural criteria provide better constraints on specific deformational events, while complexly veined zones provide an inventory of accumulated deformation within small rock volumes. Calcite cement ages cluster in 6 intervals: 290-260 Ma, 255-225 Ma, 210-180 Ma, 170-120 Ma, 60-40 Ma, and 20-5 Ma, associated with (i) Permian carbonate deposition and diagenesis, (ii) CFTB shortening, (iii) Faulting related to the early breakup of Pangea, (iv) Gulf of Mexico rifting, drifting and the Pacific tectonic influence, (v) Paleogene Mexican orogeny, and (vi) Chiapanecan orogeny and Polochic Fault System activity, respectively. All of these are important events in the evolution of the southern margin of the North American plate. This study demonstrates that calcite is resilient and reliable for preserving the history of diverse brittle deformational events imprinted in limestone.