An eolian dust origin for clastic fines of Devono-Mississippian mudrocks of the greater North American midcontinent

Autor: Austin J. McGlannan, Alicia Bonar, Lily Pfeifer, Sebastian Steinig, Paul Valdes, Steven Adams, David Duarte, Benmadi Milad, Andrew Cullen, Gerilyn S. Soreghan
Rok vydání: 2022
Předmět:
Zdroj: Journal of Sedimentary Research. 92:1186-1206
ISSN: 1938-3681
1527-1404
DOI: 10.2110/jsr.2022.013
Popis: Upper Devonian and Lower–Middle Mississippian strata of the North American midcontinent are ubiquitously fine-grained and silt-rich, comprising both so-called shale as well as argillaceous limestone (or calcareous siltstone) that accumulated in the Laurentian epeiric sea. Although long recognized as recording marine deposition, the origin and transport of the fine-grained siliciclastic material in these units remains enigmatic because they do not connect to any proximal deltaic feeder systems. Here, we present new data on grain size, whole-rock geochemistry, mineralogy, and U-Pb detrital-zircon geochronology from units across Oklahoma; we then integrate these data with models of surface wind circulation, refined paleogeographic reconstructions, and correlations from the greater midcontinent to test the hypothesis that wind transported the siliciclastic fraction to the marine system. The exclusively very fine silt to very fine sand grain size, clear detrital origin, widespread distribution over large regions of the epeiric sea, Appalachian sources, and paleogeographic setting in the subtropical arid belt far-removed from contemporaneous deltaic feeder systems are most consistent with eolian transport of dust lofted from subaerial delta plains of the greater Appalachian orogen and incorporated into subaqueous depositional systems. Delivery of dust that was minimally chemically weathered to Devono-Mississippian epeiric seas likely provided essential nutrients that stimulated organic productivity in these commonly organic-rich units.
Databáze: OpenAIRE
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