Presenter(s): Molly Pickerel
Faculty Mentor(s): Mark Reed & James Watkins
Poster 21
Session: Sciences
Recrystallized quartz grains from pre-main stage veins in the porphyry copper deposit in Butte, Montana show microscopic evidence of different temperature and pressure conditions seen through the presence of all three recrystallization regime patterns that imply a range of conditions. In this study new methods are applied to analyze recrystallized quartz veins to generate strain rate conditions not previously constrained for these veins. Thin sections of these recrystallized quartz grains are densely populated with a range of different sized fluid and mineral inclusions. The presence of these inclusions prevents the standard application of the analysis function in ImageJ to accurately measure the area of the grains and create a grain boundary map. In order to overcome this obstacle in the study Fourier transforms were created of the images and a bandpass filter applied to eliminate the frequencies of those inclusions so that the inverse Fourier Transform images did not include them. More image processing was needed to skeletonize and fill left over holes in the images before ImageJ analysis. The grain diameters collected are inputted into paleopiezometry equations from Fazio and Ortlano et al. (2018) with temperature estimates from Fouriner et al. (1999). These determined strain rates can provide insights into the conditions of the porphyry system in early stages.