Magnetic polarity stratigraphy in the uppermost Mississippian Mauch Chunk Formation, Pottsville, Pennsylvania

We took 105 oriented cores from 340 m of the upper Mauch Chunk Formation at Pottsville, Pennsylvania, for a magnetostratigraphic study. The samples were subjected to progressive thermal demagnetization from 600 to 700 degrees C and analyzed by using principal-components analysis. A high-temperature component was isolated with a mean direction of declination = 351.7 degrees , inclination = -28.4 degrees , and alpha (sub 95) = 6.7 degrees , and a corresponding paleopole at long 113.5 degrees E, lat 33.7 degrees N. Three normal and three reversed polarity magnetozones were defined, and it was found that the magnetic field was approximately 59% normal and 41% reversed in the upper Chesterian. Herein we attempt to correlate the section to a previous study in New Brunswick on the basis of the paleolatitude (pole position) and the reversal pattern, and we postulate a correlation of the bottom part of the Maringouin section with the top off the Mauch Chunk. Such a correlation would place the Mississippian/Pennsylvanian boundary within the Maringouin Formation. Earth's magnetic field was of normal polarity at the time of the Mississippian/Pennsylvanian boundary.