Earth and Planetary Sciences ETDs

Publication Date

5-13-1970

Abstract

Southwestern turquoise (CuAl6(PO4)4 OH8 · 4H2O) is associated with Laramide intrusions along the eastern and southern margins of the Colorado Plateau in Colorado, New Mexico, and Arizona, and with a zone of Late Devonian­Mississippian tectonic activity in Nevada. A review, of the previous work on the origin of turquoise is presented. Of these, the supergene hypothesis proposed by Sidney Paige in 1912 generally remains undisputed in the literature. Much of the data presented in this study, however, suggest a hydrothermal mode of formation. The concentrations of Co in particular are most similar to those of hydrothermal pyrite. Since the data do not exclude a supergene origin, it is proposed that turquoise as formed by a mixture of both hydrothermal and supergene solutions. The geochemical analyses indicate a wide range of trace-­element concentrations in turquoise, which suggests that the geologic environment was of primary importance in determining the quantities present. A comparison of the crustal abundance of the elements with their mean abundance in turquoise shows that the mineral is enriched in Pb, Zn, Ba, and Co. It is depleated relative to the crust in Cr, Fe, Mg, Ni, Sr, Mn, and V. The wide range of trace-element concentrations in turquoise may also prove useful for determining the geologic source of archaeological artifacts.

Degree Name

Earth and Planetary Sciences

Level of Degree

Masters

Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

Albert Masakiyo Kudo

Second Committee Member

Abraham Rosenzweig

Third Committee Member

J. Paul Fitzsimmons

Language

English

Document Type

Thesis

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