Olliver Plank, “Major Element Geochemistry of Pulo do Lobo Metasedimentary Rocks in SISZ”
Mentor: Dyanna Czeck, Geosciences, Letters & Science (College of)
Poster #150
Southwestern Spain is home to the Southern Iberian Shear Zone (SISZ). Shear zones are like fault zones; however, they form at depth under the extreme conditions within the Earth. These conditions deformed the Pulo do Lobo (PdL) metasedimentary rocks during the Variscan Orogeny, an event with a series of tectonic collisions about 300 million years ago. We are hoping to understand the deformation processes that operated at depth when the SISZ was active. We are using major element geochemical analysis to obtain evidence of fluid flow during shear zone deformation, which has a dramatic impact on deformation style and magnitude. To conduct geochemical analysis, first the collected samples need to be cut down small enough to be powdered. Then, they need to be baked to remove any atmospheric water remaining in the samples, which may affect the final results. After baking, samples are placed in a crucible and go through Loss on Ignition (LOI). Mass is taken of the sample in this process before and after LOI. The difference in mass is calculated to get the percentage mass lost. The sample is then turned into a disk using a flux machine and is placed into the X-ray Fluorescence machine (XRF), where the geochemical analysis of the sample is truly obtained. The data can be turned into bivariate geochemical plots to help us understand the chemical variations that are partially controlled by fluid alteration. We are expecting the new geochemical results to be similar to data collected previously by our group. We hope that these samples taken further away from the shear zone boundary were unaffected by shear zone hosted fluids to compare to the previously analyzed samples containing alteration. By studying the PdL, we hope to learn and understand more about the fluid flow and deformation history of this region.