Sequence Stratigraphy and Depositional Environments of the Shamokin (Union Springs) Mbr., Marcellus Fm. and Associated Strata in the Middle Appalachian Basin
Open Access
- Author:
- Kohl, Daniel Raymond
- Graduate Program:
- Geosciences
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- March 22, 2012
- Committee Members:
- Rudy Slingerland, Thesis Advisor/Co-Advisor
- Keywords:
- Marcellus
Mudrock
Shale
Sequence Stratigraphy
Appalachian Basin
Middle Devonian Stratigraphy
Mudstone deposition - Abstract:
- This study uses approximately 1000 wireline well logs, 8 cores, and 23 outcrops in the northern Appalachian basin (PA, NY, OH, WV, MA) to construct a sequence stratigraphic framework and depositional model of the lower portion (Union Springs mbr.) of the Middle Devonian Marcellus Formation and associated strata. Chronostratigraphic surfaces defined using sequence stratigraphic principles demonstrate that prior to the deposition of the Union Springs mbr., carbonate deposition in the western and northwestern portions of the basin produced a thick carbonate bank (Onondaga Fm.) with greater than 220 ft (61 m) of relief relative to the central, deeper portions of the basin. Continued base-level rise during deposition of late Onondaga Fm. to early Union Springs mbr. drowned out the carbonate bank and produced a relatively deep, stratified basin into which the lower portion of the Marcellus Fm was deposited. Correlations within the Marcellus Fm. indicate the Marcellus was deposited as a series of prograding muddy clinothems associated with the Mahantango Fm. delta complex. Base-level fall within the mid to upper Union Springs mbr. resulted in a forced regression and progradation of clastic sediments from the east. After the deposition of the upper Union Springs mbr., the onset of base-level rise sequestered clastic material to the east enabling widespread limestone (Purcell Mbr.) deposition on the bathymetric highs of the basin. The thickest, high TOC mudstone accumulations in the Union Springs mbr. occur in a NE to SW belt across west-central Pennsylvania. Analysis in this study indicate High TOC mudstones occur there because this region had the deepest water and was farthest from western carbonate and eastern clastic dilution.