MAPPING THE GATES-ADAH KIMBERLITE INTRUSION USING A GEM-MAGNETOMETER

The Gates-Adah Kimberlite intrusion is currently mapped as an NW-SE striking vertical intrusion in Adah, Pennsylvania. This single fissure intruded around 185-190 million years ago during the Jurassic period and is one of the only two known locations in Western Pennsylvania where Igneous rocks can be found near the surface. This intrusion cuts through the upper Pennsylvanian and lower Permian rocks of the Uniontown and Waynesburg Formations and is one of seven intrusions found in the Appalachian Plateau associated with tensional fractures formed during the rifting of Pangea and opening of the Atlantic Ocean. Though the deposit is critical to age interpretations for tectonic processes in the region, outcroppings are sparse leading to difficulties in accurate mapping and sample collection for geochronological study. To better map this intrusion and the several smaller dikes in the immediate region, magnetic data was collected with a GEM magnetometer in Gradiometer mode with continuous collection using approximately one-meter parallel spacing and reading every second. Two separate surveys were conducted in areas of interest near the known in-place outcropping of the kimberlite. Data was processed in ArcGIS and compared to published geologic maps to determine accuracy. Points were color-coded based on the strength of the reading and show a clear trend demonstrating a new interpretation of the local dike location. If new locations for less weathered sample collection can be determined, more samples may be collected to potentially determine the age of crystallization and its relationship to local tectonic events.