RETHINKING THE VOCABULARY FOR CARBONATE FAULT ROCKS
Carbonate rocks pose additional challenges to observation, classification and interpretation. Carbonates form different structures than silicates when exposed to the same deformational conditions so generic schemes may not be applicable to carbonates. Carbonate rocks can display a convergence of deformational fabrics with primary or early diagenetic features (for example, ultramylonitic marble can be strikingly similar in outcrop to micritic limestone). The relationships between conditions of deformation and microstructure are often complex and non-unique. In particular, dissolution and precipitation are more influential in carbonate rocks than in silicates. We are building a classification system and associated workflow for carbonate fault rocks based on a global gallery that is descriptive, and can be applied in the field, and extended for microscopy work. We emphasize those attributes which are important for the interpretation of the formation and evolution of fault rocks. We hope to make the new classification scheme accessible for general use by the many disciplines who map, collect, or study carbonate rocks. We are eager for community feedback and advice to test and broaden the utility of our preliminary scheme.