Investigating the petrology and microstructures of achondrite meteorites

Davies, Faye (2023) Investigating the petrology and microstructures of achondrite meteorites. MRes thesis, University of Glasgow.

Abstract

Achondrite meteorites provide us with important information about differentiated planetary bodies of the early Solar System, as these meteorites have been melted and recrystallised to various degrees throughout their geological history with the source of these meteorites being the outer shell of differentiated parent bodies. The textural relationships within achondrite meteorites provide important evidence of the formation, size, evolution and destruction of the Solar System’s first planetesimals.

The focus of this research is using a variety of achondrite meteorites similar to rocks which are found on Earth. Using a range of SEM techniques such as EDS, EBSD and EMPA to observe the crystallography of each meteorite and study the deformation structures and relationship between the grains to provide an insight into the history of the planetary bodies from which each of these meteorites originated.

The key findings from this research were that ureilites have olivine grains that display Mgrich reduction rims with Fe-metal blebs surrounding Mg-poor cores as well as iron veining throughout the samples. These textures are interpreted as a redox reaction where carbon acts as a catalyst reacting with Fe within the olivine grains forming Mg-rich rims and Fe-metal veining throughout the samples. The degree to which the reaction has taken place varies between the samples based on the carbon and iron percentages observed as a decrease in carbon percentage resulting in an increase in the iron percentage of the sample for each ureilite studied within the research. Anomalous achondrite MIL 090356 displays similar chemical reactions to the ureilites and these are interpreted to be caused by an impact event on the parent body. While iron veining is still present on MIL 090356, the catalyst for the reaction is sulphur infiltration within the sample rather than carbon as was the case for the ureilites. Evidence for similar Sulphur catalysed chemical reactions have also been suggested for brachinites which MIL 090356 is closely affiliated. This provides evidence that similar chemical processes occurred on more than one planetary body beyond 1 AU from the Sun within the same outer region of the solar nebula. The aubrite Cumberland Falls which formed within the inner 1 AU of the early Solar System contains chondritic material including barred olivine-pyroxene chondrules, this chondritic material is classified as enstatite chondrite. These enstatite clasts have not been found before and add to the suite of ordinary chondrite clasts and forsterite chondrite clasts that have been described previously. 2 Together these chondritic clasts provide evidence of complete mixing of chondritic material within the inner Solar System.

This research has provided an insight into processes of other planetary bodies and their formation as well as the earliest periods in the solar system history allowing for a more in-depth complete picture of the behaviour of rocky worlds in the solar system.

• Item Type: Thesis (MRes)
• Qualification Level: Masters
• Subjects: Q Science > QE Geology
• Colleges/Schools: College of Science and Engineering > School of Geographical and Earth Sciences > Earth Sciences
• Supervisor's Name: Daly, Dr. Luke and Hallis, Dr. Lydia
• Date of Award: 2023
• Depositing User: Theses Team
• Unique ID: glathesis:2023-83804
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 06 Sep 2023 07:38
• Last Modified: 06 Sep 2023 07:59
• Thesis DOI: 10.5525/gla.thesis.83804
• URI: https://theses.gla.ac.uk/id/eprint/83804