TECTONIC EVOLUTION OF ROCKS OF THE SOUTHERN APPALACHIANS IN THE PROTEROZOIC EON

In the Southern Appalachian orogenic belt there are Proterozoic gneisses that show higher grade metamorphism than younger Proterozoic rocks of the region. Previous studies have reported pre-Grenville U-Pb zircon ages in these high-grade gneisses, up to ~1.8 Ga. This study aims to gain insight to these units’ tectonic history by looking at the pre-Grenvillian record preserved in the samples. Since these rocks record older ages and intense metamorphism, we theorize that these rocks are exotic to Laurentia. Our investigation centers around mineralogical, structural, and geochemical analysis. Whole-rock samples have been chemically analyzed in XRF, and we have done analysis on specific minerals in thin section with SEM. Out of the 6 thin sections analyzed, muscovite and amphiboles are absent in all samples. Quartz crystals commonly display undulose extinction. This indicates high-grade metamorphism compared to Grenville-aged Proterozoic rocks of the southern Appalachians. Structural data has been plotted on a map to show orientation relative to other units in the region. With further investigation into the structure and orientation of these samples, we will be able to better constrain the tectonic events that first formed these rocks, and the mechanisms that emplaced them.