New Mexico Geological Society Annual Spring Meeting — Abstracts

This study will determine the depositional environment of siderite and calcite precipitation hosted in the coal-bearing Crevasse Canyon Formation in west-central New Mexico. Siderite (FeCO₃), which forms under reduced anoxic conditions during carbonation, is a useful indicator of redox conditions during diagenesis and its presence with calcite in the sandstones and shales of the Crevasse Canyon Formation provides evidence of a complex diagenetic environment during the Late Cretaceous. I will utilize a combination of petrography, whole rock major and trace element geochemistry, and mineral chemistry to relate compositional variability to each macro- and micro-texture of carbonate precipitation. The composition of the rocks hosting, and in contact with, siderite-bearing rocks will be characterized using Scanning Electron Microscopy (SEM), Electron Probe Micro-Analysis (EPMA), X-ray Fluorescence (XRF) spectrometry, and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The mineral assemblage of the rocks will provide insight into the range of carbonate compositions, which when combined with detailed textural analyses, will be used to determine whether siderite and calcite formed from single- or multi-stage precipitation. Using these methods, the depositional settings that enabled the formation of siderite will be determined. The precipitation of siderite requires distinct environmental factors and by understanding how the different categories of siderite precipitate, this study can be a reference point for analysis of siderite found in other locations around the world.