Off-campus UNL users: To download campus access dissertations, please use the following link to log into our proxy server with your NU ID and password. When you are done browsing please remember to return to this page and log out.
Non-UNL users: Please talk to your librarian about requesting this dissertation through interlibrary loan.
A SEDIMENTOLOGIC AND PETROGRAPHIC STUDY OF THE MIOCENE ARIKAREE GROUP OF SOUTH-EASTERN WYOMING AND WEST-CENTRAL NEBRASKA.
Abstract
Miocene Arikaree deposits of the High Plains of west- ern Nebraska and eastern Wyoming consist of volcaniclastic air fall material and minor epiclastic detritus. These sediments represent formation by two primary depositional processes: aeolian and fluvial.Aeolian materials are widely dispersed throughout the area and include thick bedded leessic deposits, reworked aeolian-fluvial deposits and large scale cross-beds produced in migrating barchan and transverse dunes. The abundance of air-fall rhyolitic shards reflect Miocene volcanism in the Rocky Mountains.Fluvial deposits represent four main lithofacies within a braided stream system. They include 13 parallel-laminated, floodplain deposits, 2) large-scale, cross-stratifications of migrating bars, 3) ripples and cross-strata of the active channel facies and 4) abandoned-channel, ash deposits. Multi- variate analysis of detrital modes of sandstones indicate complete, statistically-defined dispersal patterns for these deposits.Study of the Arikaree and underlying Brule sediments (of the White River Group) indicate that these deposits are complexly interbedded. Lithologic similarity of the Goring and Monroe Creek Formations of the Arikazee Group makes separa tion of these formations impossible in the study area. Differ entiation of these deposits based on the presence or type of concretions was found to be unreliable.A three level fluvial model is presented for the Arikaree and consists of numerous stream systems each consisting of a series of anastomosing channels separated by islands and/or migrating bars. These streams had high fluctuations in dis- charge, high sediment load and erodible banks and migrated laterally over broad floodplains.
Subject Area
Geology
Recommended Citation
BART, HENRY ANTHONY, "A SEDIMENTOLOGIC AND PETROGRAPHIC STUDY OF THE MIOCENE ARIKAREE GROUP OF SOUTH-EASTERN WYOMING AND WEST-CENTRAL NEBRASKA." (1974). ETD collection for University of Nebraska-Lincoln. AAI7503409.
https://digitalcommons.unl.edu/dissertations/AAI7503409