Ben Wachholz '24

Ben Wachholz '24: Research with Jeff Rahl, Summer 2021

This summer, I was fortunate enough to spend 8 weeks as a research assistant for Dr. Rahl. During this time, I worked alongside Dr. Rahl and learned new techniques. I spent the first six weeks in the lab assisting Dr. Rahl on his exploration of transcontinental sediment transportation. Dr. Rahl is interested in a transcontinental drainage system that flowed westwardly from the Appalachian mountains and was diverted by the ancestorial rocky mountains, an intracratonic block uplift, which formed 325 ma. By studying the thermochronology and geochronology of zircon crystals, which were extracted from samples taken from sediment basins created by the ancestorial rocky mountains, we can infer the provenance of the crystals. In the lab, I spent much of my time conducting mineral separation to extract zircon crystals for analysis. Learning how to do mineral separation was a valuable experience that allowed me to learn how to operate many machines such as Frantz magnetic separator and a water table.

In addition to mineral separation, my time in the lab was also spent conducting energy dispersive X-ray spectroscopy (EDS) in conjunction with a scanning electron microscope (SEM). I performed analysis on thin sections of samples taken from the ancestorial rocky mountains. Using the SEM and EDS I was able to create maps of the thin sections highlighting potassium feldspar grains. These maps would then be used at another lab to identify and date the appropriate grains. Using the SEM and EDS was a great experience that gave me hands-on practice using advanced technology in a lab setting.

My last two weeks as a research assistant were spent in the field. We spent the first week in southern Oklahoma searching for carbonates from the Arbuckle mountains. The Arbuckle mountains were the southernmost uplift of the ancestorial rocky mountains. The goal of collecting carbonates is to perform calcite twin analysis. Calcite twin analysis allows us to infer the direction of stress which caused the grain to deform or ‘twin.' We can then use the inferred direction of stress to make inferences on the formation of the ancestorial rocky mountains, whose formation factors are debated. My time in the field allowed me to learn how to identify and extract proper samples. I became more proficient in analyzing the composition of a sample in a field setting and learned how to use a Brunton compass.

My second week in the field was spent in northern New Mexico exploring the Taos trough. Here we saw many interesting rock formations and lots of spectacular views. In the field, we worked to gather more samples for further zircon analysis to discover more about transcontinental sediment transportation. This fieldwork gave me more experience with using tools and taking notes in the field. Additionally, through Jeff's teachings, I was able to see and learn more about geologic formations.

Support provided by a NSF grant and the Geology Department