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This study attempts to advance the understanding of the geometry of the Survant Coal Member of the Linton Formation (Pennsylvanian) in Indiana. We documented variability in the thickness and lateral extent of the coal beds present between the Mecca Quarry Shale Member of the Linton Formation and the Excello Shale Member of the Petersburg Formation—two transgressive traceable marine horizons. Our study was based on the detailed examination of 1,240 petroleum geophysical logs and coal test borehole logs throughout Indiana, and on previously collected data. The presence of multiple coal beds in the Survant Coal Member and variable thickness of the clastic partings create mapping challenges and difficulties in reliably evaluating coal resources, as well as stratigraphic uncertainties and confusion related to the nomenclature used for this coal. Because one to four coal beds occur between the Mecca Quarry Shale Member and the Excello Shale Member (namely, between the Colchester and Houchin Creek Coal Members of the Linton and Petersburg Formations), it is unclear which seams should be included in the Survant Coal Member. To better depict the complexity of the Survant Coal Member, we suggest that two additional locations be considered as reference sections. The first auxiliary reference section is Indiana Geological and Water Survey (formerly, Indiana Geological Survey) drill core SDH-366 (Petroleum Database Management System [PDMS] #150359) from Vanderburgh County (PDMS, 2018). This reference section represents the more southern part of Indiana where two coal benches are separated by a thick clastic interval. The second auxiliary reference section is drill core SDH-235 (PDMS #157302) in Greene County, representative of the central part Indiana where two distinct coal benches are separated by a relatively thin clastic parting. These two additional sections together with the current reference section (SDH-306 [PDMS #115871] located in Pike County in southern Indiana) capture the complexity of the Survant Coal Member more comprehensively than the current reference section alone.
This study provides new data on the geometry of the coal beds within the Survant Coal Member that will allow more reliable future resource and reserve evaluation of this coal. In addition, we have also compiled information about mining, resources, and properties of this coal to provide a comprehensive reference for the Survant Coal Member in Indiana.