Abstract

Late Mississippian rocks in southwestern New Mexico are represented by the Paradise Formation. The Paradise is a 130 m thick mixed carbonate-clastic sequence that is composed of 30 parasequences. These parasequences are made up of seven distinctive lithofacies: grainstones, packstone, wackestone, lime mudstone, sandstone, siltstone, and shale. Petrographic and cathodoluminescent petrography of the first six of these lithofacies led to the identification of a variety of diagenetic features. These diagenetic features fall into seven primary categories: calcite cementation (marine and freshwater), micritization, neomorphism, silicification, dissolution, compaction and fracturing, quartz cementation, and dolomitization. Most diagenetic features occur throughout the formation, although early marine cements are rare. Some diagenetic minerals are facies specific. Low-Mg calcite cement occurs predominantly in the lower two-thirds of the section. By evaluating cross-cutting relationships in thin section the following paragenetic sequence was constructed: Marine cementation, micritization, aggrading neomorphism, high-Mg calcite to low-Mg calcite, aragonite dissolution synchronous with silicification or dolomitization (facies specific), low-Mg calcite cementation, fracturing, ferroan calcite (burial) cementation, quartz cementation or dolomitization. With the exception of aragonite dissolution, fracturing, and dolomitization, diagenetic processes resulted in the occlusion of all porosity and permeability. Pervasive diagenesis effectively makes the Paradise Formation unsuitable as a hydrocarbon reservoir in the Big Hatchet Mountains region.