HYDROTHERMAL ALTERATION IN CARBONATE RICH IGNEOUS COMPLEX OF MAGNET COVE, ARKANSAS AS ANALOG TO NILI FOSSAE AND GUSEV, MARS

While Mars is no longer volcanically active, it once was home to many active volcanoes, implying the presence of magma chambers below its surface. Magma chambers are a common source of heat necessary for hydrothermal activity, such as hot springs. One such location is Magnet Cove, an igneous complex in central Arkansas. Petrographic and X-ray powder diffraction analysis were performed on core samples taken from Magnet Cove and the carbonate-rich rocks are likely carbonatite, a calcium-rich igneous rock, indicative of volcanic activity. Near the center of the core the composition changes drastically; natrolite and epidote, along with other trace minerals, were found. These minerals are commonly found in environments where hydrothermal alteration occurs. Hydrothermal alteration is the process in which hot fluids flow through preexisting rock and chemically alter the rock. Compositions of both the fluid and rock, temperature, and pressure all contribute to the alteration process. Because the pluton was highly calcitic, the formation of epidote would require the fluid to contain both Al3+ and Fe3+ and natrolite needs both sodium and aluminum silicate. This area of probable hydrothermal alteration in a preexisting pluton suggests volcanic activity may be a driving force for the geothermal heating of water in central Arkansas. Utilizing the data collected along with CRISM spectrometer data of Nili Fossae and Gusev, central Arkansas could be analogous to carbonate-rich areas of Mars, providing evidence for once-active geothermal springs driven by volcanic activity.