Carbonates and Other Salts in the Atacama Desert and on Mars, and the Implications for the Role of Life in Carbonate Formation

Persistent Link:
http://hdl.handle.net/10150/556965
Title:
Carbonates and Other Salts in the Atacama Desert and on Mars, and the Implications for the Role of Life in Carbonate Formation
Author:
Harner, Patrick Lee
Issue Date:
2015
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The scarcity of carbonate on Mars has been difficult to reconcile with the morphologic evidence for a wet epoch in Martian history, and has weakened early interpretations of a water-rich Noachian. Limited soil carbonate from pre-Silurian Earth has created a similar conundrum, and in both instances this paradox has likely led to overreaching interpretations about past climates. To better understand the formation of carbonate on Mars, early Earth, and in present day hyperarid climates, we examined the distribution of carbonate in the Atacama Desert—a region that spans multiple climate regimes and allows us to isolate the effects of precipitation and plant cover on soil mineralogy. To better quantify the influences of vegetation on carbonate we utilized a simple one-dimensional precipitation model and simulated carbonate formation with or without plant cover under a range of relevant climatic conditions and soil morphologies. In the Atacama we found two distinct zones with only trace (<5%) carbonate: the "absolute desert" with precipitation too low to sustain plant life, and the high Andes where precipitation was significantly higher, but where the low mean annual temperature (MAT) inhibits plants. The fog-supported, low-elevation coastal "lomas" below approximately 800 meters above sea level (masl) and the higher elevations between approximately 2500-4500 masl are variably vegetated and contain abundant carbonate within the soils. Plants increase total evapotranspiration and its distribution with depth, weathering rates, and total pCO₂. Our model results show that all of these factors increase the formation of pedogenic soil carbonate. Without the influence of vegetation the diminished carbonate that is produced is flushed through the shallow soil, where it eventually precipitates in the deep vadose zone or is entrained by groundwater.
Type:
text; Electronic Thesis
Keywords:
Carbonate; hyperarid; Mars; Plant; Stable Isotope; Planetary Sciences; Atacama
Degree Name:
M.S.
Degree Level:
masters
Degree Program:
Graduate College; Planetary Sciences
Degree Grantor:
University of Arizona
Advisor:
Baker, Victor; Quade, Jay

Full metadata record

DC FieldValue Language
dc.language.isoen_USen
dc.titleCarbonates and Other Salts in the Atacama Desert and on Mars, and the Implications for the Role of Life in Carbonate Formationen_US
dc.creatorHarner, Patrick Leeen
dc.contributor.authorHarner, Patrick Leeen
dc.date.issued2015en
dc.publisherThe University of Arizona.en
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en
dc.description.abstractThe scarcity of carbonate on Mars has been difficult to reconcile with the morphologic evidence for a wet epoch in Martian history, and has weakened early interpretations of a water-rich Noachian. Limited soil carbonate from pre-Silurian Earth has created a similar conundrum, and in both instances this paradox has likely led to overreaching interpretations about past climates. To better understand the formation of carbonate on Mars, early Earth, and in present day hyperarid climates, we examined the distribution of carbonate in the Atacama Desert—a region that spans multiple climate regimes and allows us to isolate the effects of precipitation and plant cover on soil mineralogy. To better quantify the influences of vegetation on carbonate we utilized a simple one-dimensional precipitation model and simulated carbonate formation with or without plant cover under a range of relevant climatic conditions and soil morphologies. In the Atacama we found two distinct zones with only trace (<5%) carbonate: the "absolute desert" with precipitation too low to sustain plant life, and the high Andes where precipitation was significantly higher, but where the low mean annual temperature (MAT) inhibits plants. The fog-supported, low-elevation coastal "lomas" below approximately 800 meters above sea level (masl) and the higher elevations between approximately 2500-4500 masl are variably vegetated and contain abundant carbonate within the soils. Plants increase total evapotranspiration and its distribution with depth, weathering rates, and total pCO₂. Our model results show that all of these factors increase the formation of pedogenic soil carbonate. Without the influence of vegetation the diminished carbonate that is produced is flushed through the shallow soil, where it eventually precipitates in the deep vadose zone or is entrained by groundwater.en
dc.typetexten
dc.typeElectronic Thesisen
dc.subjectCarbonateen
dc.subjecthyperariden
dc.subjectMarsen
dc.subjectPlanten
dc.subjectStable Isotopeen
dc.subjectPlanetary Sciencesen
dc.subjectAtacamaen
thesis.degree.nameM.S.en
thesis.degree.levelmastersen
thesis.degree.disciplineGraduate Collegeen
thesis.degree.disciplinePlanetary Sciencesen
thesis.degree.grantorUniversity of Arizonaen
dc.contributor.advisorBaker, Victoren
dc.contributor.advisorQuade, Jayen
dc.contributor.committeememberBaker, Victoren
dc.contributor.committeememberQuade, Jayen
dc.contributor.committeememberSwindle, Timen
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