Salem Limestone (Valmeyeran, Mississippian)—A high-energy carbonate shoal model
Brian D. Keith*, Todd A. Thompson*, 2018. "Salem Limestone (Valmeyeran, Mississippian)—A high-energy carbonate shoal model", Ancient Oceans, Orogenic Uplifts, and Glacial Ice: Geologic Crossroads in America’s Heartland, Lee J. Florea
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The Salem Limestone (Valmeyeran, Mississippian) is a preeminent dimensional limestone quarried in a two-county area of south-central Indiana for nearly 200 years. Advances in quarry technology in the past 30 years produce nearly smooth-sawn quarry walls that show the exquisite depositional details of the Salem carbonate shoal.
The Salem shoal is part of a large-scale shoaling sequence that produced a carbonate platform during the middle Mississippian that began at the end of Borden Group (Mississippian) delta deposition and culminated with the deposition of the Ste. Genevieve Limestone (Mississippian). The Salem was deposited as a high-energy, but subtidal shoal above fair-weather wave base. Four environments are recognizable within the shoal: active shoal, open lagoon, intrashoal channel, and intershoal channel. A shoal crest environment may also be present as a fifth environment. A hierarchy of bounding surfaces can be defined using the sawed quarry exposures. First-order surfaces are foreset laminae and appear as inclined or horizontal stratification. Second-order surfaces are the contacts between similar bedforms, and third-order surfaces truncate first- and second-order surfaces, representing breaks in sedimentation. Combined they define mesoforms within the shoal complex. Fourth-order surfaces, similar to third-order surfaces, represent a change from a shoal to lagoonal setting. Evidence of hard-ground development occurs along third-order surfaces, associated with encrusting bryozoan holdfasts, corals, and columnar subtidal stromatolites. Tracing surfaces on the quarry walls is vital to reconstructing the internal architecture of the shoal and the processes that operated within it. We will examine this shoal architecture by visiting quarries and an outcrop, and we will visit a mill where quarried stone blocks are fabricated into panels and shapes for buildings.
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This volume, prepared for the 130th Annual Meeting of the Geological Society of America in Indianapolis, includes compelling science and field trips in Indiana, Illinois, Kentucky, Michigan, and Ohio. A wealth of geologic and human history collides in the Midwest, a confluence that led to the growth of America's industry over the past two centuries. Guides in this volume depict this development from the establishment of New Harmony, the birthplace of American geology, through the construction of Indianapolis's modern skyline. Underpinning this growth were the widespread natural resources-limestone, coal, and water-that built, powered, and connected a growing nation. Take a journey through the Heartland to sand dunes, outcrops, quarries, rivers, caves, and springs that connect Paleozoic stratigraphy with the assembly of Gondwana, continental glaciation with Quaternary geomorphology and hydrology, and landscape with the human environment.