Upper Ordovician and Silurian Stratigraphy of the Virginia and West Virginia Valley and Ridge: Sedimentary and Structural Effects of the Taconic Orogeny
Richard J. Diecchio, 1986. "Upper Ordovician and Silurian Stratigraphy of the Virginia and West Virginia Valley and Ridge: Sedimentary and Structural Effects of the Taconic Orogeny", Southeastern United States: Third Annual Midyear Meeting, 1986, Raleigh, North Carolina, Daniel A. Textoris
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Two pronounced effects of the Taconic Orogeny were the creation of an eastern source area which influenced sedimentation through much of the Appalachian basin, and the early deformation of the eastern margin of the Appalachian basin. This field trip will investigate the stratigraphy of the Taconian (Upper Ordovician) and post-Taconian (Silurian) clastic strata in an attempt to illustrate the sedimentologic and structural effects of the Taconic Orogeny in the eastern portion of the Appalachian basin.
The Taconian clastic sequence is an orogenic progradational sequence. The distal (western) facies of the clastic sequence were deposited between the carbonate shelf and the source area, in a deep basin which was created by tectonic downwarping of the eastern edge of the carbonate bank. During deposition of the Taconian clastics, there occurred a pronounced, probably glacio-eustatic lowering of sea level, which lasted until the beginning of the Silurian.
The Silurian clastics are a series of post-orogenic quartz sandstones and mudrocks, the upper portion of which changes facies basinward to limestone. The sandstones comprise a number of tongues which are thickest near the basin margin, and thin to the west. The Silurian strata were deposited in relatively shallow water, implying that tectonic downwarping had ceased. The large-scale inter-tonguing of strata may have been caused by sea-level fluctuations.
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Southeastern United States–Guidebook is comprised of twelve field trips that were organized for the Third Annual Midyear Meeting held in Raleigh, North Carolina in 1986. The spectrum of geologic time represented in the Upper Precambrian, Lower Paleozoic, Mesozoic, Cenozoic and the very Recent. The geologic provinces are the Valley and Ridge, Blue Ridge Mountains, Piedmont, and the Coastal Plain. Besides North Carolina, trips include Virginia, South Carolina and West Virginia.