The Origin and Relationships Between Olivine and Phlogopite Phenocrysts of the Avon Diatreme
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
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.
Comments
Joint project with Elliott France