Browsing by Author "McClung, Wilson S."

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    Drainage area estimates for synorogenic clastic wedges in the Central Appalachian Basin (sink) with implications for terrane accretion in the hinterland (source)
    Eriksson, Kenneth A.; McClung, Wilson S.; Simpson, Edward L. (Wiley, 2023-03)
    Source-to-sink studies typically utilize the sedimentary record preserved in basins to infer source area parameters such as estimates of drainage area and discharges of fluvial systems in the hinterland, the characterization of which remains elusive as few geomorphic elements of the hinterland are preserved. Clastic wedges within foreland basin settings often contain fluvial deposits, and the scale of fluvial architectural elements can be used to estimate drainage area and discharge within the accreted hinterland. This study uses thicknesses of fluvial architectural elements within the Late Ordovician Taconic, the Late Devonian-Early Mississippian Acadian, and the Late Mississippian to Early and Middle Pennsylvanian Alleghanian clastic wedges, together with climatic conditions interpreted from palaeosol data, to estimate the drainage areas and discharges of the river systems which drained the hinterlands of the accreted Taconic and Acadian terrains and the Alleghanian suture of Laurentia and Gondwana. Published detrital zircon age spectra provide insight into ages of source areas of sediments as well as the timing of terrane accretion. The increase in hinterland drainage areas calculated for Late Devonian Acadian Orogeny river systems compared to Late Ordovician Taconic Orogeny river systems can be attributed to the increase in size of accreted terranes to the east of the foreland basins during that period of time. The decrease in hinterland drainage area from the Late Devonian Acadian Orogeny to the Middle to Late Pennsylvanian Alleghanian Orogeny is attributed to the westward migration of the drainage divide as the Alleghanian orogeny proceeded. It is inferred that the drainage divide migrated towards the drier leeward side of the mountain range and caused drainage basins to shrink and split into smaller drainage basins.
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    Marine offshore to alluvial plain transitions within the "Chemung"-Hamsphire interval (Upper Devonian) of the southern central Appalachians
    McClung, Wilson S. (Virginia Polytechnic Institute and State University, 1983)
    The Upper Devonian "Chemung" and Hampshire Formations of the southern Central Appalachian basin constitute the upper strata of an eastward thickening wedge of elastic sediment. The sediments comprising the "Chemung" and Hampshire, deposited on a low-gradient marine shelf and alluvial plain, respectively, are syn- to post-orogenic (Acadian), and were derived from the erosion of the Acadian Mountains to the east. Facies of the "Chemung" indicate deposition within three major, laterally adjacent environments. The predominating facies assemblage constitutes upward-coarsening sequences interpreted as offshore to upper shoreface progradational successions. The sequences are storm- and wave-dominated and pass upward into storm- and wave-dominated shoal water delta facies or into low-energy subtidal to supratidal mudflat facies. The absence of beaches and tidal channels is indicative not only of low tidal ranges, but also of seaward dissipation of wave-energy within a very shallow intracratonic foreland basin. The easternmost sections of the Hampshire Formation are comprised of fluvial cycles interpreted as high-energy sheetflood deposits.This style of sedimentation developed in closest proximity to the source. The Hampshire of more western sections is constructed predominantly of cycles interpreted as low-sinuosity braided stream deposits with a lesser abundance of cycles deposited by high-sinuosity meandering streams and high-energy sheetfloods. Low depositional slopes were associated with the alluvial plain. Braiding, however, was probably due to high runoff associated with high rainfall in a tropical climate and inadequate floodplain stabilization by vegetation, resulting in periodic high discharge.