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Early Earth oxygen dynamics

Summer 2024

Project Background

Molecular oxygen (O2) is abundant at Earth’s surface today, comprising 21% of the atmosphere by dry volume. But this was not always the case. For the first two billion years of Earth’s existence, O2 was a trace atmospheric gas of no more than 0.00002%. What changed? When did it change?

The goal of this project is to better understand the initial rise of O2 on Earth. To do this we will use a combination of geology and chemistry, or geochemistry. Some of the chemical characteristics of early Earth’s surface are preserved in the sedimentary record. We will attempt to pry them out.

Student Role

As a summer undergraduate researcher in the Ostrander Lab, you will study ancient sedimentary rocks formed on the seafloor during the initial rise of O2. Well-preserved shale and carbonate drill-core samples are already collected from this time interval. What you will be tasked with is preparing the samples for geochemical analyses. Our goal will be to generate a suite of trace element abundance and stable isotope data. While completing these tasks, you will be introduced to the logic that guides the application of these geochemical tools. These lessons will be supplemented by your own personal reviews of relevant literature.

Student Learning Outcomes and Benefits

By the end of the summer, you will gain experience in novel geochemical techniques. This includes (but is not limited to) acid digestion, partial extraction, inductively coupled plasma mass spectrometry (ICPMS), and multi-collector ICPMS. You will gain the fundamental knowledge base required to think critically about ancient Earth. And you will have the pleasure of interacting with and learning from a diverse set of faculty, staff, and students in the Department of Geology and Geophysics.

Chad Ostrander

Assistant Professor
Mines & Earth Sciences
Geology & Geophysics

I try to keep my mentoring philosophy simple. Most of the students I mentor are interested, or at least potentially interested, in becoming scientists. My philosophy therefore leans heavily on the application of the scientific method. Question: what are the questions worth asking? In most cases with young mentees, this burden is best navigated by the mentor. Research: what is the current state of knowledge? This is oftentimes the initial task for the mentee: to get acquainted with the current state of knowledge via existing literature and discussions with the mentor. Hypothesize: what do you think the answer to the question is? I think it is important to let the mentee formulate their own initial hypotheses; the mentor should abstain from providing input, at least at first. Test: what can we do to assess whether the hypothesis is correct or incorrect? For young mentees, formulation of the initial test(s) is probably best navigated by the mentor. Analyze: what do the collected data mean, and are they consistent or inconsistent with the favored hypothesis? This is another step I believe should be left to the mentee, at least at first, with minimal input from the mentor. With each successive application of the scientific method, a larger burden should be transferred to the mentee, with the penultimate goal being independence. Throughout the process I believe it is important to always leave room for initiative, and to allow mentees to make mistakes.