Title page for ETD etd-04112011-141942


Type of Document Master's Thesis
Author Blue, Christina Renee
Author's Email Address cblue@vt.edu
URN etd-04112011-141942
Title Stratigraphic Architecture and Paleogeography of the Juniata Formation, Central Appalachians
Degree Master of Science
Department Geosciences
Advisory Committee
Advisor Name Title
Eriksson, Kenneth A. Committee Chair
Diecchio, Richard J. Committee Member
Read, James Fredrick Committee Member
Keywords
  • Tuscarora Unconformity
  • Taconic Orogeny
  • shoreface deposits
  • paleogeography
  • Late Ordovician
  • Juniata Formation
  • Central Appalachian Basin
Date of Defense 2011-03-28
Availability unrestricted
Abstract
Late Ordovician (Cincinnatian) strata of the central Appalachians provide an opportunity to study the effects of both tectonics and eustasy within a foreland-basin setting. The Juniata Formation consists of red sandstones, siltstones, and shales that were deposited as part of an extensive siliciclastic basin-fill that resulted from the Taconic Orogeny. This study attempts to resolve some of the questions regarding tectonic and eustatic influences on sedimentation by (1) reconstructing the paleogeographic environment of the Juniata Formation and (2) examining the stratigraphic architecture of the Juniata Formation. A combination of both outcrop and subsurface data was analyzed.

Seven facies were identified in this study, including: (1) “proto-vertisols”, (2) red shale/mudstone, (3) siltstone/silty mudstone with interbedded sandstones, (4) quartz arenite and sublithic arenite, (5) argillaceous sandstone, (6) hummocky-bedded sandstones and siltstones, and (7) lithic sandstones and conglomerates. These facies are grouped into four facies associations (A–D), which are interpreted to be deposited from the inner shelf to the upper shoreface. Isopach and paleocurrent data suggest the shoreline was oriented NE–SW and detrital sediment was dispersed west and southwest across the basin.

Tectonics controlled the 2nd-Order basin-fill pattern, and these patterns vary along the strike of the basin. Eustatic changes are expressed in two 3rd-Order sequences that were identified in the formation, and possibly in the 4th-Order (?) cycles of Facies Association A. The Ordovician–Silurian boundary is expressed as an unconformity throughout the study area, and along-strike variations in the structural setting of the basin were important in its development.

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