Description
- Abstract:
- The climatic history of Mars has been indirectly studied through the remote detection of minerals produced by chemical alteration across its surface. While the martian surface has experienced cold, dry, and oxidizing conditions over prolonged geologic timescales, few studies have investigated the role of chemical alteration in this type of environment, largely due to the slow kinetics of alteration and the difficulties in preserving these metastable weathering products in natural settings. In this work, we identify, characterize, and interpret oxidative weathering processes and products in the Ferrar Dolerite of Beacon Valley, Antarctica, where these phases are uniquely preserved due to the hyper-arid and hypo-thermal environmental conditions. The oxidation process results in the predictable migration of cations in response to an oxidizing environment, resulting in diagnostic chemical and spectral signatures in the absence of significant mineralogical variations. The distribution of these alteration phases was then assessed throughout the McMurdo Dry Valleys of Antarctica using remote spectroscopic datasets. This study confirms that oxidative weathering products are confined to Beacon Valley as well as our ability to identify these alteration signatures amidst a diversity of complex lithological and spectral signatures. <br/><br/> The ability to characterize these metastable alteration products using remote spectroscopic techniques and to relate these signatures to detailed laboratory investigations substantiates our capabilities of performing similar analyses across the martian surface. Visible/near-infrared reflectance and thermal infrared emission datasets exhibit spectral signatures that are uniquely consistent with the widespread presence of oxidative weathering products on Mars. These signatures were previously interpreted as representing hydrated mineral phases, and their widespread distribution across the martian surface would imply pervasive and geologically recent aqueous activity. However, further investigations of regional dust-free terrains do not reveal spectral evidence for hydrated signatures in the near-infrared. As a result, the dominance of oxidative weathering products throughout these basaltic terrains suggests that liquid water has been an inconsequential component of regional chemical alteration across the martian surface since these landscapes were formed approximately three billion years ago.
- Notes:
- Thesis (Ph.D. -- Brown University (2013)
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Citation
Salvatore, Mark,
"Geochemical Signatures of Stable Planetary Surfaces: Oxidative Weathering Processes on Earth and Mars"
(2013).
Earth, Environmental and Planetary Sciences Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z0V69GWR
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Earth, Environmental and Planetary Sciences Theses and Dissertations
Theses and Dissertations for the Earth, Environmental and Planetary Sciences department....