Sponsor
Portland State University. Department of Geology
First Advisor
Alexander Ruzicka
Term of Graduation
Winter 2025
Date of Publication
2-19-2025
Document Type
Thesis
Degree Name
Master of Science (M.S.) in Geology
Department
Geology
Language
English
Subjects
Diaplectic glass, Diffusion, EDS EBSD SEM, High pressure phases, Maskelynite, Shergottites
Physical Description
1 online resource (xviii, 146 pages)
Abstract
Martian meteorites result from large impact events on the surface of Mars that cause intense shock metamorphism. This study examines the shock metamorphic features of three shergottite meteorites, Dho 019, NWA 12241, and NWA 15628, to better understand shock impact events. The research uses petrographic analysis, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and electron backscatter diffraction (EBSD) to analyze the meteorites. A key focus of this research is the formation of maskelynite, a glass with plagioclase composition, whose formation mechanism has been the substance of debate among researchers. This study proposes that maskelynite forms through a transient intermediary glass state, exhibiting solid-state transformation and melting characteristics. Shock timescales were estimated by analyzing diffusion profiles in maskelynite grains. The calculated timescales using diffusion timescales are on the order of milliseconds to seconds. In addition, high-pressure phases in melt pockets were studied to trace pressure temperature paths during shock metamorphism.
This research provides a more nuanced understanding of shock metamorphism in Martian meteorites, offering new insights into maskelynite formation, shock duration, and the pressure-temperature conditions of impact events on Mars.
Rights
In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
Persistent Identifier
https://archives.pdx.edu/ds/psu/43186
Recommended Citation
Anim, George Ayeh, "Shock Effects Including Maskelynite Formation in Three Shergottite Meteorites From Mars" (2025). Dissertations and Theses. Paper 6792.
