Discovering Bio-Signatures in Microbial Dolomite using Trace Metal Analysis and Magnesium and Strontium Stable Isotope Analysis

Abstract:

UCSC GEOPATHS is an NSF-supported initiative to improve student success in geosciences, driven by a desire to broaden participation. One component of the program is undergraduate student internship that provide authentic, career-relevant experiences – across all employment sector – to increase student engagement in the geoscience pipeline.

The GEOPATHS internship at Dr. Adina Paytan’s Biogeochemistry Lab, as well as the W.M. Keck Isotope laboratory at UCSC was focused on separation and analysis of biogenic dolomite found in hypersaline microbial mats. The extraction of dolomite from raw fractions was performed using various physical and chemical treatments; after which stable isotope analysis was performed to determine if Magnesium and Strontium isotopes could be used to explain the mechanisms of dolomite formation. Although the mineral dolomite is quite abundant in geological records, its formation in modern environment is rare. One possible explanation for this apparent contradiction is that the predominant mode of dolomite formation is through replacement of Ca-Carbonate minerals during burial diagenesis. However, another, explanation for the high dolomite abundances in the geological past is the existence of sedimentary environments favorable for microbially-mediated dolomite formation. The possibility of distinguishing the two modes of dolomite formation were explored using Magnesium and Strontium stable isotopes in modern sediments.

Not only did the internship help me master analytical instruments and techniques that I had previously been aware of (SEM, XRD and mineral separation) but it also introduced me to new analytical tools and techniques such as Clean Lab work and use of tools such as ICP-OES and stable isotope mass spectrometer. The internship overall provided me with real life working experience with constant aid and guidance from my peers as well as my mentors and I intend to share the results of my project and experiences in the program.