Paleomagnetism of the Maringouin and Shepody formations, New Brunswick: a Namurian magnetic stratigraphy

Abstract

Two hundred thirty-five oriented cores were taken in a stratigraphic sequence of 575 m of red sediments from the Namurian Maringouin and Shepody formations. These samples were taken from the south-dipping limb of the Maringouin Anticline on the Maringouin Peninsula in eastern New Brunswick. An additional 59 samples of the Maringouin and Shepody formations were taken from the north-dipping limb for separate fold tests. Progressive thermal demagnetization to temperatures as high as 700 °C permitted the resolution of an intermediate-temperature, syn-folding B component and a high-temperature, pre-folding C component. The C-component mean for the Maringouin Formation yields a north paleopole at 32.4°N, 121.3°E. The Shepody Formation mean yields a paleopole at 35.7°N, 124.3°E. The circles of confidence (α95) for the Maringouin and Shepody formations are 3.8 °and 4.6°, respectively. Plotting sample polarity versus stratigraphie position yields the first coherent magnetic stratigraphy from the late Paleozoic of North America, with five discrete reversed-polarity and five discrete normal-polarity zones. The magnetic field in Namurian times had approximately 50% normal and 50% reversed polarity.