MAGNETIC AND MINERALOGICAL INVESTIGATIONS OF PHYLLITE LAYERS FROM THE BARABOO AREA, WI

We investigated the magnetic mineralogy and remanent magnetic directions of phyllite layers in the Baraboo area of Wisconsin to aid in resolving the deformation age of the syncline. The phyllites, which were originally clay-rich layers of sediment, are assumed to have formed during the deformational formation of the Baraboo Syncline. Saturation isothermal remanent magnetism (SIRM) analysis, magnetic hyteresis properties, and thermal demagnetization studies indicate magnetite and/or maghemite, and hematite are present. The paleomagnetic directions obtained from samples on either side of the syncline, are dissimilar especially in the inclinations. These results are similar to the earlier work of Kean and Mercer (1986). Complete unfolding of the syncline does not improve the results, which suggests the magnetism is probably synfolding in age.

Kean, W.F., and Mercer, D., 1986, Preliminary Paleomagnetic Study of the Baraboo Quartzite, Wisconsin. Geoscience Wisconsin, vol. 10, pp. 46-53.