Mappin'
Without Diggin': An Application of Magnetometry Techniques in
the Rittenhouse Gap Mining District in Berks County,
Pennsylvania
Hoefert
Catherine M., Burris, Lea, Yenchik, John, Black, Laurel E.,
and Friehauf, Kurt
C., 2003, Mappin'
Without
Diggin': An Application of Magnetometry Techniques in the
Rittenhouse Gap Mining District in Berks County, Pennsylvania
[abs.]: Geological Society of America Northeastern Section - 38th
Annual Meeting (March 27–29, 2003) Halifax, Nova Scotia, Program
with Abstracts, vol. 35, no. 3, p. 94.
Magnetite veins in the Rittenhouse Gap
iron-mining district located in Berks County, Pennsylvania are
parallel, but offset in a stepped fashion, cutting Proterozoic
granitic gneisses. Forest litter obscures all of the outcrop, making
geologic mapping difficult. We used a hand-held proton procession
magnetometer coupled with a GPS receiver, sampling with a two-meter
area, and compiled our data with GIS to map the magnetic field in
the iron-mining district. We interpreted the variations in the
magnetic data in terms of wall rock hydrothermal alteration,
calibrated by comparing magnetic data with petrographic studies of
rocks exposed in the iron-mine region. In order to determine whether
the district’s en echelon vein pattern reflects a large-scale Reidel
shear fracture, or offsets of a simple vein by cross faults, a
larger study area involving smaller grids of magnetometer readings
would generate a clearer and decisive underground petrology picture.