Revisiting the Paleoproterozoic Baraboo interval in southern Wisconsin: Evidence for syn-depositional tectonism along the south-central margin of Laurentia

New Precambrian geologic mapping within the core of the Baraboo syncline, Baraboo Ranges, WI, confirms early interpretations of local stratigraphy. The Baraboo interval section includes two upward-fining sequences separated by an angular unconformity. The lower sequence comprises the Baraboo Quartzite, Seeley Slate, and Freedom Formation. The upper sequence comprises the Dake Quartzite and Rowley Creek Slate. The depositional age of the upper sequence is poorly constrained, but could be nearly 200 million years younger than the underlying units. U-Pb detrital zircon ages for the lower conglomeratic Baraboo Quartzite and the Dake Quartzite are dominated by nearby basement ages between 1800 and 1750 Ma and 1900-1835 Ma, suggesting a restricted drainage system tapping proximal basement sources. Subsidence modeling of the lower sequence demonstrates at least 1.28 km of subsidence is required to generate the accommodation necessary to deposit the Baraboo Quartzite, Seeley Slate and Freedom Formation. These results support a model where deposition of the lower sequence between ca. 1710-1650 Ma occurred along a tectonically active plate margin. The lack of coeval magmatism in the Baraboo interval suggests deposition did not occur in a convergent, arc setting. However, coeval orthoquartzite deposition in Colorado, Arizona, and New Mexico along the southwestern margin of Laurentia (1700-1650 Ma) occurred synchronous with arc volcanism, requiring a component of plate margin convergence to the southwest. To reconcile these differences, a model where the entire southern margin of Laurentia between 1710 and 1650 Ma was dominated by strike-slip motion is favored, varying from highly oblique convergence in the southwest to dominantly strike-slip motion in the southern Lake Superior region.