Stratigraphic analysis of key beds in cyclothems in the Staunton Formation (Middle Pennsylvanian) in the Clinton Area, west-central Indiana

摘要: ABSTRACT During a coal resources study in the Clinton area, covering 260 square miles, author found that six unnamed and little understood beds lie within an average vertical interval of 62 ft Staunton Formation (middle Pennsylvanian) were difficult to identify correlate. A these was made, using data from numerous outcrops test holes. These coals resemble one another physical appearance spore content, but each occurs separate cyclothem. The cyclothems are designated informally through F ascending order. key beds, nearly identical lithologically cyclothem, vary thickness discontinuous geographic distribution. table histograms summarize results stratigraphic analysis continuity (underclay-limestone, underclay, coal, carbonaceous black shale, marine limestone) intervals between Seelyville Coal Member (III), which marks top Staunton, coals. Limestone is absent F; two types limestones gradually increase distribution cyclothem E B; five coexist with most frequency D contains widespread shale; common key-bed lithology. unit yet only 70 percent stragitraphic sections. More than half occur 50 or fewer facts indicate high degree discontinuity lithologic units caused difficulty identification correlation. Tentative correlation area made generalized geologic columns other areas, published, large part. All correlated Dubois County, Fountain, Warren, northern Vermillion Counties; Brazil Quadrangles, Clay County: four Spencer County; three near Oakland City, Gibson County.