Paleomagnetism of the distal member of the New Glasgow formation, Nova Scotia, Canada: New constraints on magnetic polarity stratigraphy near the base of the Kiaman Superchron

The ca. 315-260-Ma Kiaman Reversed (Permo-Carboniferous) Magnetic Superchron is an important time marker that can be used for correlation of stratigraphic sequences from a local to a global scale. Earlier workers, from a paleomagnetic study of the Joggins stratigraphic section of the western Cumberland Basin of Nova Scotia, demonstrated that the base of the superchron lies above redbeds of the lowermost portion of the late Namurian-Westphalian A Boss Point Formation. Although a detailed sequence of reversals was observed below this point, no normal magnetic polarity zones were recognized above it. In our study, samples were collected from redbeds of the distal member of the Westphalian A New Glasgow formation of the eastern Cumberland Basin, which directly overlie the gray sandstones of the Boss Point Formation. Most sampling sites carry a normal polarity magnetization, probably acquired at about the time of deposition. Therefore, the base of the Kiaman Reversed Superchron lies within or above the New Glasgow formation. Either the top of the Boss Point Formation is diachronous between the two areas, or, more likely, the base of the superchron is significantly higher in the stratigraphic section than previously recognized, a conclusion that is important for both intrabasin and intercontinental stratigraphic correlations. It implies that the pattern of pre-Kiaman magnetic reversals reported from below the Boss Point Formation in the Joggins section is significantly older than previously thought and, therefore, cannot be used for comparison with magnetic reversal patterns that closely underlie the base of the superchron at other localities in the Cumberland Basin or on other continents.