Master's Theses

Date of Award

1979

Degree Name

Master of Science (MS)

Department

Geosciences

Advisor

Michael E. Nelson

Abstract

Detailed field mapping and sedimentary analysis has revealed the physical stratigraphy, depositional environment, and provenance of the sediment in a small, but geologically important area (Sections 16, 17, 20, and 21, T. 33 S., R. 28 W.) in Meade County, Kansas. Terrigenous sediment was deposited episodically between the Miocene and Pleistocene (Nebraskan?) in a fluvial depositional environment that contained both meandering and braided streams. Immature arkosic sandstones and conglomerates of the Taloga , Ogallala , Rexroad, and Ballard Formations; and immature subarkosic sand- and siltstones of the Crooked Creek Formation and the undifferentiated Sanborn Group crop out in the study area. Three heavy mineral assemblages characterize the sand fractions of these formations. Garnet, amphibole, and epldote-clinozoisite characterize the Taloga and Ogallala; epidote-clinozoisite, garnet, and amphibole characterize the Rexroad and Ballard; and epidote-clinozoisite, garnet, amphibole, and zircon characterize the Crooked Creek and Sanborn. Important clay minerals include montmorillonite, illite, and kaolinite. Textural cyclicity and compositional variability of the deposits may reflect climatic changes, upward pulsations in the Rocky Mountains, regional shifting of major channels, or some combination of these processes. The sediment originated from multiple sources including plutonic and metamorphic rocks of the Rocky Mountains, sedimentary rocks of southeastern Colorado and southwestern Kansas, and extrusive rocks of Colorado, New Mexico, and Wyoming. Paleontological evidence suggests that a warm, moist climate probably prevailed throughout the depositional period.

Rights

Copyright 1979 James T. Kovach

Comments

Notice: This material may be protected by copyright law (Title 17 U.S. Code).

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