ANALYSIS OF 11 MA COUGAR POINT TUFF UNIT XIII, KNOLL BASIN, NE NEVADA USING XRD, SEM, MICRO-XRF, FTIR, AND RAMAN

Igneous petrologists investigate Earth’s past events and processes to better understand natural processes such as volcanic eruptions. Advances in geochemical analyses may facilitate the investigation of these processes. In the case of the Knoll basin, the reconstruction of a volcano’s activity during its life can help predict the outcomes of volcanic activity. In order to better characterize a specific ancient eruption, ten Cougar Point Tuff Unit XIII samples were collected from Knoll basin at four locations. Samples were analyzed alongside glass material research specialists with a goal of learning new geochemical techniques from their unique viewpoint.

Two sample types were prepared for testing. Heavy liquid separated glass matrix was used in x-ray diffraction spectroscopy (XRD) and Fourier transform infrared spectroscope (FTIR). Whole sample epoxy mounts were used in scanning electron microscopy (SEM), micro x-ray fluorescence (micro-XRF), and Raman spectroscopy. X-ray diffraction spectroscopy confirmed the amorphous structure of the samples’ matrix and paucity of crystals, confirming the glass-crystal separation procedure. Backscatter electron imaging identified eight unique compositional phases: a silica dioxide phase (glass), quartz, ilmenite, magnetite, sanidine, calcite, augite, and zircon. The micro-XRF elemental maps identified the matrix is composed of two intergrown glass phases. Multivariate analysis of Raman and Fourier Transform Infrared spectral data will be used to determine subtle structural differences among the samples