trilobite Isotelus gigas
Trenton Black River Project
Petrography
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PETROGRAPHY OF THE TRENTON AND BLACK RIVER GROUP CARBONATE ROCKS IN THE APPALACHIAN BASIN

Introduction | Methods | Constituents | Microfacies and Depositional Environments | Diagenesis | Dolomite Textures, Diagenesis, and Porosity |
References | Text Figures | Appendix I [Skeletal (PDF) - Nonskeletal (PDF)] | Appendix II (PDF) |
Appendix III-Figure Captions | Appendix IV-Figure Captions | Appendix V-Figure Captions |
Table 1 - TBR Core and Outcrop Samples (PDF)

METHODS

We collected samples from 17 different cores of Trenton and/or Black River carbonate rocks recovered from wells throughout the Appalachian basin. The cores we examined and sampled are listed in Table 1. We described the cores before sampling, and these descriptions will be integrated into the pending reports on stratigraphy. We also collected cuttings samples from one well in Pennsylvania for thin sections, and prepared numerous thin sections from outcrop samples in Pennsylvania and Kentucky. In all, we analyzed 740 thin sections of Trenton and Black River carbonates. Selected samples were further studied by scanning electron microscopy and energy-dispersive X-ray spectroscopy.

We used a Leica DML polarizing microscope equipped with a Leica DFC camera for all transmitted light microscopy. We examined selected unembedded and unpolished samples on a Hitachi S-2600N variable pressure scanning electron microscope (SEM) operating with a pressure of 10 Pascals using the backscattered electron detection imaging system at 20 kV and a working distance of 15 mm. The elemental composition of these samples was determined using Quartz Imaging System's Quartz XOne energy-dispersive X-ray spectroscopy (EDS) package with a Gresham Sirius 10/UTW/SEM detector having a 10 mm2 crystal and an ultra thin polymer window. We used the same SEM operating at 20 kV and a working distance of 15 mm when conducting EDS analyses.

We classified all carbonate rock samples using the classification systems of both Dunham (1962) and Folk (1962). We found Dunham's (1962) classification useful for microfacies analysis when we could use it - it is descriptive, objective, and easy to use in the field or laboratory, and it conveys some genetic information. But the Dunham classification fell short in naming many of the Trenton and Black River limestones and dolostones significantly altered by diagenesis. In these instances the Folk (1962) classification system provided us with a useful, objective and descriptive terminology that provided for grain size, allochem composition, and diagenetic alterations. For these reasons, we use carbonate names from both systems interchangeably throughout this report. We classified all dolostones using the classification system of Wright (2001). We classified carbonate porosity using the systems of both Choquette and Pray (1970) and Luo and Machel (1995). to top