Title

The Origin and Relationships Between Olivine and Phlogopite Phenocrysts of the Avon Diatreme

Presenter Information

Tiffany Wysong

Department

Geosciences and Geological and Petroleum Engineering

Major

Geology and Geophysics

Research Advisor

Hogan, John Patrick

Advisor's Department

Geosciences and Geological and Petroleum Engineering

Funding Source

OURE

Abstract

We investigated an analysis of the petrographic and compositional relationships between olivine, biotite, and phlogopite present within an alnöite of the Avon Alkaline Igneous Province located in Genevieve County, Missouri. The olivine may have been used in a reaction with feldspar to create phlogopite, given by the reaction: 3 (Mg,Fe)2SiO4 + 2 KAlSi3O8 + 2 H2O = 2 K(Mg,Fe)3AlSi3O10(OH)2 + 3 SiO2

This possible reaction implies assimilation of granitic crust into an intrusive mafic melt. Other possibilities for the observed textures include fractionation of a mafic melt to destabilize the olivine and/or the mixing of two seperate magmas.

Anhedral olivine grains are more heavily fractured than euhedral crystals, as they are surrounded and embayed by phlogopite crystals. Isotope geochemistry of the olivine crystals support that there is only one population of olivines. Alternatively, the avon diatreme magma source could have been metasomatized after crystallization.

Biography

Tiffany is originally from St. Louis, Missouri and is a senior in Geology & Geophysics. She was awarded the Bob Laudon Advanced Field Camp Award for exemplary field notes and maps in Utah under the teachings of Dr. John Hogan. Tiffany plans on attending graduate school to further her knowledge in igneous processes, magma chamber dynamics, and related geochemistry.

Research Category

Sciences

Presentation Type

Poster Presentation

Document Type

Poster

Location

Upper Atrium

Presentation Date

17 Apr 2018, 9:00 am - 12:00 pm

Comments

Joint project with Elliott France

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Apr 17th, 9:00 AM Apr 17th, 12:00 PM

The Origin and Relationships Between Olivine and Phlogopite Phenocrysts of the Avon Diatreme

Upper Atrium

We investigated an analysis of the petrographic and compositional relationships between olivine, biotite, and phlogopite present within an alnöite of the Avon Alkaline Igneous Province located in Genevieve County, Missouri. The olivine may have been used in a reaction with feldspar to create phlogopite, given by the reaction: 3 (Mg,Fe)2SiO4 + 2 KAlSi3O8 + 2 H2O = 2 K(Mg,Fe)3AlSi3O10(OH)2 + 3 SiO2

This possible reaction implies assimilation of granitic crust into an intrusive mafic melt. Other possibilities for the observed textures include fractionation of a mafic melt to destabilize the olivine and/or the mixing of two seperate magmas.

Anhedral olivine grains are more heavily fractured than euhedral crystals, as they are surrounded and embayed by phlogopite crystals. Isotope geochemistry of the olivine crystals support that there is only one population of olivines. Alternatively, the avon diatreme magma source could have been metasomatized after crystallization.