Date of Graduation

5-2016

Document Type

Thesis

Degree Name

Master of Science in Geology (MS)

Degree Level

Graduate

Department

Geosciences

Advisor

Walter L. Manger

Committee Member

Adriana Potra

Second Committee Member

Erik Pollock

Third Committee Member

Doy Zachry

Keywords

Earth sciences; Arkansas novaculite; Boone formation; Chert; Novaculite; Silica source; Volcanic; silica

Abstract

Geochemical analyses of the Arkansas Novaculite, located within core structures of the Ouachita Mountains in west-central Arkansas, and penecontemporaneous chert of the lower Boone Formation, located atop the Springfield Plateau of southwest Missouri, northwest Arkansas, and northeast Oklahoma, have identified a significant concentration of both aluminum and potassium. This would seem to eliminate a biogenic origin and favor a volcanic source of the silica that comprises these units. Trace and rare earth element (REE) analysis also suggests that the Arkansas Novaculite and the chert in the lower Boone Formation may have both been formed from the same volcanic source.

The volcanic signatures of these two formations were compared to average elemental concentrations of continental, Aleutian, and boninite magmatic bodies. Both the Arkansas Novaculite and Boone Formation resemble a boninitic magmatic body in composition. Second order mantle melt needed to create this titanium depleted primitive andesitic body would have been generated as the Gondwana landmass approached the North American craton throughout the Devonian and Lower Mississippian periods, eventually closing the Ouachita Trough during the Ouachita Orogeny (Pennsylvanian).

Field samples of the Arkansas Novaculite were collected at Caddo Gap, Arkansas, while the Boone Formation was sampled across southwest Missouri and northwest Arkansas. Both the energy-dispersive X-ray and mass spectrometry analysis was performed at the University of Arkansas’ Nano-Bio Materials Characterization Facility and Department of Chemistry, respectively.

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