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Date of Award

Summer 2024

Document Type

Masters Thesis

Department or Program Affiliation

Geology

Degree Name

Master of Science (MS)

Department

Geology

First Advisor

Rice, Melissa S.

Second Advisor

Boujibar, Asmaa

Third Advisor

Pfeiffer, Allison

Abstract

Examining loose pieces of rock separated from outcrops, or “float” rocks, at Jezero crater, Mars, and comparing them to in-place outcrops can provide key insights into the crater’s erosional history, the units in the Jezero watershed that the Perseverance rover cannot visit in-situ, and the geologic context for any future returned samples. Here, we used multispectral observations from the Mastcam-Z instrument on the Mars 2020 Perseverance rover to investigate the lithology and origin of float rocks found on the western Jezero fan front (sols 415-707). We identified four textural classes of float rocks (conglomerates, layered, massive, and light-toned). We then investigated the spectral properties and distribution of each class along the fan front to interpret their source and mode of transport. We found that the conglomerate and layered float rocks are highly spectrally variable, altered, and oxidized with differing ferric and ferrous signatures, and they likely derived from local coarse-grained and planar laminated outcrops of the sedimentary Shenandoah formation in the western fan front. Massive float rocks are the least altered, exhibit ferrous signatures, and were divided into olivine and low-Ca pyroxene subclasses. Massive float rocks at the fan front could have derived from proximal, local outcrop sources such as the Knobs fan front member, coarse deposits in the fan top, crater rim, or more distal sources in the Jezero watershed. The massive olivine subclass likely derived from the regional olivine-carbonate-bearing unit, while the massive pyroxene subclass likely derived from the Noachian basement unit in the watershed. The light-toned float rocks have spectral signatures consistent with hydrated and Fe-poor phases, and they have no local outcrop equivalent of these rocks in the western Jezero fan or crater floor. This study provides a basis of comparison and testable hypotheses for Perseverance’s ongoing investigations of boulders present at the fan top and future investigations of the Jezero crater rim.

Type

Text

Keywords

Mars, Perseverance rover, Jezero crater, float rocks, spectroscopy, multispectral imaging, Mastcam-Z

Publisher

Western Washington University

OCLC Number

1449999702

Subject – LCSH

Igneous rocks; Martian craters; Roving vehicles (Astronautics)

Geographic Coverage

Mars (Planet)

Format

application/pdf

Genre/Form

masters theses

Language

English

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.

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