Date of Graduation

5-2017

Document Type

Thesis

Degree Name

Master of Science in Geology (MS)

Degree Level

Graduate

Department

Geosciences

Advisor/Mentor

Shaw, John B.

Committee Member

Zachry, Doy L.

Second Committee Member

Covington, Matthew D.

Third Committee Member

McGilvery, T.A. "Mac"

Keywords

Cross-sets; Middle Bloyd; Paleohydraulics; Paleozoic Rivers; Parthenon; Stratigraphy

Abstract

In this thesis, set thicknesses are used to estimate the paleohydraulics (paleodischarge and give magnitudes for paleocurrent directions) of the ancient river system which deposited the Parthenon Sandstone in northwest Arkansas. Set thickness is the vertical thickness of a group of strata conformable series (Mckee and Weir, 1953); set thickness represents truncated dunes. The goal of this thesis is to: 1) obtain paleodischarge estimates of the Parthenon sandstone via cross-sets and compare the results with previously calculated discharge estimates which use basin area to discharge collation techniques and 2) use paleodischarge estimates calculated within this thesis to give magnitude to the paleocurrent direction data and compare the results with, more traditional, non-vector paleocurrent direction data. The quantitative work that has been done on the Parthenon suggests a paleodischarge which differs from qualitative estimates by multiple orders of magnitude; resulting in the need for more research. By obtaining quantitative measurements of set thickness, grain size, and paleocurrent direction on twenty-one Parthenon outcrops (over a 4.5x103 km2 study area), multiple paleohydraulic parameters can be estimated with existing models including: mean bedform height, channel depth, channel belt width, channel width, paleoslope, boundary shear stress, Darcy-Weisbach friction factor, paleoflow velocity, paleodischarge, and overall paleocurrent direction. Paleodischarge estimates in this study average 13,000 m3/s; the minimum estimates average 2,200 m3/s; and the maximum estimates average 53,000 m3/s. Maximum average estimates in this study are lower than the minimum estimates (64,000 m3/s) from past research based on total basin area; estimates in this thesis remain many orders of magnitude larger than any modern flashy system (the type of system the Parthenon has been interpreted as in the past). The overall paleocurrent direction found in this thesis is to the southwest; similar to past analyses. The total mean paleocurrent direction is 211 degrees; the mean of the outcrop means is 191 degree; and the mean of the paleodischarge weighted outcrop means is 198 degrees. There is little change between the overall paleocurrent directions when using vector or just directional data.

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