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Distal orogenic effects on peripheral bulge sedimentation: Middle and Upper Ordovician of the Nashville Dome

Journal Article · · Journal of Sedimentary Research, Section A: Sedimentary Petrology and Processes
OSTI ID:460583
 [1];  [2]
  1. Univ. of Georgia, Athens, GA (United States). Dept. of Geology
  2. Pennsylvania State Univ., University Park, PA (United States). Dept. of Geosciences
A major switch in depositional style in the Ordovician carbonates of the Nashville Dome corresponds closely with the onset of the late Middle Ordovician Taconic orogeny. This time marks a shift from tropical-type to temperate-type carbonates, the initiation of widespread major phosphate deposition, the introduction of large amounts of terrigenous silt and clay, the occurrence of widespread seismically induced soft-sediment deformation, and a change from a low-energy flat-topped carbonate shelf to a high-energy doubly dipping carbonate ramp. Soft-sediment deformation and the introduction of siliciclastics are direct effects of the Taconic orogeny; the switch from tropical-type to temperate-type carbonates, the initiation of phosphate deposition, and the switch in carbonate ramp are largely oceanographic effects triggered by the orogeny. In particular, phosphate deposition and the switch to temperate-type limestones appears to have been driven by upwelling along the eastern side of the Nashville Dome within the newly deepened Taconic foreland basin. A fourfold decrease in the rate of relative sea-level rise occurred on the Nashville Dome nearly 3 m.y. following the onset of thrusting and foreland basin initiation. Subsidence rates were constant before and after this decrease, and no evidence of a change in subsidence rates is seen to coincide with the onset of thrusting. The slowing of subsidence may reflect viscoelastic uplift of the Nashville Dome, but the abrupt change from one constant subsidence rate to another is not predicted by existing foreland basin models.
Sponsoring Organization:
Petroleum Research Fund (United States)
OSTI ID:
460583
Journal Information:
Journal of Sedimentary Research, Section A: Sedimentary Petrology and Processes, Journal Name: Journal of Sedimentary Research, Section A: Sedimentary Petrology and Processes Journal Issue: 2 Vol. 67; ISSN JSRAEA; ISSN 1073-130X
Country of Publication:
United States
Language:
English

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