Year of Award

2021

Document Type

Thesis

Degree Type

Master of Science (MS)

Degree Name

Geosciences

Department or School/College

Geosciences

Committee Chair

Nancy Hinman

Committee Co-chair

Hilary Martens, Jesse Johnson

Commitee Members

Nancy Hinman, Hilary Martens, Jesse Johnson

Keywords

stromatolites, biosignatures, fractals, astrobiology, diffusion-limited aggregation, modeling

Subject Categories

Biogeochemistry | Other Microbiology | Paleontology

Abstract

Stromatolites, microbialites, and other microbially induced sedimentary structures exist in the rock record as far back as 3.6 billion years ago and continue to form in the present day. Better characterizing these structures and better understanding how they form is crucial in distinguishing these biosignatures from similar, abiotic structures, which can help us to understand the conditions of early Earth and early Mars. To that end, I have modified DLA 3D EXT, an open-source stromatolite modeling program, to more closely reflect the process of microbial trapping-and-binding by filamentous microbes in a calcite-precipitating hot spring system. This modified program includes a field of upright spikes that can trap incoming particles and sediment. I simulated stromatolites forming with different spike heights, spike spacings, and stickiness. To quantify these stromatolites’ morphologies, I obtained the fractal dimension and lacunarity of a section of each resulting structure. I found that stickiness affects morphology as measured by both fractal dimension and lacunarity. This may help us better distinguish true stromatolites from abiotic imposters.

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© Copyright 2021 Laura E. Stevens