Dylan Childs, “Analyzing Water Infiltration in Fault Sourced Quartz Crystals”
Mentor: Dyanna Czeck, Geosciences
Poster #37

Variables like composition, pressure, and temperature all have influences on how rocks react to stress. Under stress, generally rocks at the surface break (brittle deformation) and rocks deeper in the crust bend without losing cohesion (ductile deformation). The goal of this research is to better understand how water infiltration influences whether rocks will break or bend. By grinding down rock samples into a 0.03-millimeter thickness and gluing them in between glass slides, these samples are thin enough for light to travel through and prepared for microscopic analysis. With a microscope, these thin sections reveal individual crystals composing the rock and observations can be made on them. However, before any data collection can begin for this research project, first equipment needs to be properly calibrated. Time on this project has largely been spent leveling the lapping plates to a precise enough flatness for the creation of thin sections. Although the plates may appear flat to the naked eye, sensitive gauges are used to measure the slightest curvature present on the surface. Without this process, any slight changes in slope left on the plates are enough to break the thin, fragile rock samples when ground down. After all the equipment is calibrated, future work will be grinding granitic rock samples into thin sections. Once the sections are ready, individual quartz crystals will be analyzed for quartz-filled microfractures through observations made with a microscope. Microfractures in crystals form by tectonic stresses. Further analysis at Advance Light Source at UC Berkeley will reveal the concentrations of water present in the quartz within the fractures. These observations will allow us to better understand how water enhances ductile deformation.