Mid-Atlantic Iron Belt Project - Phase 2 - Rittenhouse Gap Geophysical Reconnaissance Survey

Kurt Friehauf - Kutztown University

Four undergraduates student involved:
Project:  Using GPS integrated with a laser surveyor to determine precise locations of measurements, students used a proton precession magnetometer and gamma ray spectrometer to measure the intensity of the magnetic field and the gamma emissions of basement rocks beneath thick soil cover.  The intensity of the earth’s magnetic field is locally affected by the presence of magnetic minerals in rock.  Gamma rays are emitted from rocks as minute amounts of radioactive isotopes that are present in all rocks decay.  The intensity of different types of gamma ray emissions translates directly into the concentrations of potassium, uranium, and thorium in the rock.  Measurements were made along two 80-meter long linear traverses spaced every two meters.  Because the magnetometer, GPS, and gamma ray spectrometer can potentially interfere with each other’s measurements, we required a 3-4-person team for data collection to keep the devices separated by a safe distance.

Results: Although gamma ray data did not have a recognizable pattern, possibly due to varying thickness of soil cover “shielding” gamma emissions, the magnetic data clearly demonstrated that we could successfully identify the locations of magnetite veins buried beneath the forest litter.  Laser surveying was successful for determining sample location because tree cover blocked GPS signals, although the close spacing of trees prevented long distance shots.  We concluded that standard GPS techniques would be quicker if we made measurements late in the fall or in winter when tree canopy was clear. 

on to Phase 3 - Rittenhouse Geophysical Survey

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