Date of Award

Summer 2017

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Geosciences

Committee Chair

Alysia Cox

First Advisor

Katie Hailer

Second Advisor

Christopher Gammons

Third Advisor

William Drury

Abstract

Mudpots are acidic, turbid thermal features formed by the argillic or sericitic alteration of rock with enough fluid to create a viscous feature. Prior to this research, the combination of interdisciplinary sampling for geochemistry, mineralogy, and microbiology of rhyolite hosted mudpots, particularly in chemically distinct subregions of an area, remained largely unavailable. This work discusses mudpots and nearby hot springs sampled in Yellowstone National Park (YNP) in July 2016 and the measured in situ pH, temperature, and conductivity values, and dissolved oxygen concentrations. Water, filtered via gravity pre-filtration and 1.2 μm and 0.8/0.2μm syringe filtration, yielded δD and δ18O values and major anions, cations, and trace element concentrations. Sediment collected for biological and mineralogical analysis revealed that mudpots, with approximate viscosities ranging from 5 to 100 centipose (mPa*s), had trace element geochemical “fingerprints” that can be linked with underlying rock units. Turbid hot springs of similar pH and temperature lacked consistent chemical similarity to mudpots, however mudpots shared chemical similarity with respect to major anions and cations to hot springs from similar thermal source waters. Chloride concentrations and δD determined similarities between source waters. Despite having similar concentrations of major anions and cations with nearby acid sulfate hot springs, mudpots differ from these hot springs in their trace element relative abundance “fingerprints” that make connections between surficial geochemistry and variations in chemical composition of underlying rock units. Such comparisons are not possible with hot springs. 16S and 18S rRNA gene microbial diversity analyses show that mudpots host organisms with a variety of known metabolisms, such as methanogenesis, nitrification, and ammonia oxidation. There are microbes common to thermal areas in mudpots, however no genus common to all mudpots. Mudpots, formed by alteration of volcanic rock by acidic steam, serve as both indicators of underlying geology and distinct microbial ecosystems offering insight into potentially ancient analogs.

Comments

A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Geoscience: Geochemistry Option

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