ANALYSIS OF BASALTS AND METABASALTS FROM SCATTERED LOCATIONS IN THE UNITED STATES

An unknown specimen was compared to a known specimen through elemental analysis in order to determine the unknown’s composition and igneous rock classification. The two specimens were analyzed using Energy Dispersive Spectroscopy (EDS) after being coated in platinum using a sputter coater (EMS150TS) in the labs at Kent State University at Stark. For the chemical analysis of both specimens, a Scanning Electron Microscope (SEM), model JEOL JSM-6010 Plus/LV, as well as an Energy Dispersive Spectrometer (EDS), model Oxford Instruments X-Max, were used. This research was done to determine the chemical differences in two different potential basalt protoliths. Specimen 1 contains high weight percentages of oxygen, carbon, silicon, iron, and aluminum. Common minerals that are formed due to these chemicals would be quartz (SiO₂), olivine ((Mg,Fe)₂SiO₄), garnets/almandine (Fe₃Al₂Si₃O₁₂), and potentially corundum (Al₂O₃). Specimen 2 was found to have similarly high amounts of oxygen, carbon, silicon, and aluminum, but contained much less iron in its weight percentage instead having calcium much higher. Due to the relative abundance of calcium, it is likely that Specimen 2 contains much higher levels of diopside (CaMg(Si₂O₆)) compared to Specimen 1. The initial hypothesis that both specimens were of basalt origin was supported. Minerals like chlorite form when a basaltic (mafic) rock is metamorphosed. The metamorphic specimen, Specimen 1, contains higher levels of the elements magnesium, aluminum, and iron that are needed when forming chlorite, thus providing insight into the relative product-versus-protolith relationship. The results from this research suggest that Specimen 1 had a mafic protolith, where Specimen 2 was most likely an andesite or a basaltic andesite.