The Precambrian bedrock of northern Wisconsin hosts the 1.8-1.9Ga billion-year-old Penokean Orogeny. The Penokean Orogeny involves the collision of volcanic arcs and smaller continental crustal blocks. These blocks are known as the Pembine-Wausau Terrane and the Marshfield Terrane. The Eau Pleine Shear Zone marks the boundary between these two terranes. Recent studies within the Marshfield Terrane indicate a more complex geological structure than previously understood, the highly variable ages in this area highlight the need to re-evaluate the significance of this structural boundary between the Pembine-Wausau and Marshfield terranes. Clusters of magmatic rocks found near the Eau Pleine Shear Zone could help determine the nature of this crustal boundary. Magmas that are generated before, during, or after the collision inherit the geochemical and isotopic characteristics of the crustal blocks they interact with. For this research project, samples were collected from both intrusive and volcanic rocks that are found on both sides of the Eau Pleine Shear Zone, these samples were then prepared for geochemical and petrographic analysis. The results of this work will allow us to evaluate historical tectonic models of the Lake Superior region and determine whether the Eau Pleine Shear Zone is indeed an appropriate terrane boundary.
The volcanic rocks of the Penokean orogen of northern Wisconsin are well known for hosting 1875 Ma Cu-Zn-Pb-Au-Ag volcanogenic massive sulfide (VMS) deposits that formed in deep marine extensional settings. New U/Pb ages obtained from VMS-hosting volcanic strata suggest the extensional tectonic setting was active at 1835 Ma when previous tectonic models state the Penokean Orogen is thought to have closed the ocean. These inconsistencies in dates of samples from the Penokean Orogen may suggest a different geologic timeline than previously recognized. However, younger tectonic or hydrothermal may have altered the zircon U/Pb systematics. This study compares U/Pb ages taken from zircon cores or rims to test if there is a difference in the data. If there is a correlation between core/rim analyses and ages, then it is possible that the 1835 Ma age is an artifact of tectonic or hydrothermal events and not related to timing of VMS mineralization. Preliminary core vs. rim comparisons indicates there is no distinct difference in the ages. This suggests that the younger submarine extensional VMS-forming environment existed and that the timing of major events in the Penokean orogen need to be revisited.
Flushing of non-degrading waste can lead to costly blockages in wastewater treatment systems. This study investigated Eau Claire County residents’ perspectives on and habits of flushing non-degrading waste. To test our hypothesis that residents with on-site septic systems are more aware of proper flushing habits than residents whose sewage flows to the municipal wastewater treatment plant, we distributed 444 surveys in neighborhoods that were on the municipal system and others with an on-site septic system. We received 43 responses from septic and municipal residences, with response rates of 28% and 15%, respectively. Municipal residents were more likely to identify that non-flushable wipes and feminine hygiene products should not be flushed (by 19% and 9%, respectively) and they reported experiencing clogs at a significantly lower rate (-33%). We contacted three local septic service companies who all stated most septic system blockages are caused by non-woven wet wipes with some blockages caused by feminine hygiene products. These insights, combined with survey results, suggest that septic system residents are more invested in what gets flushed than municipal residents, but are less aware of proper flushing habits. This study will be used to develop an outreach program on the importance of proper flushing habits.
In geochronology, mineral separation is a critical prerequisite for obtaining datable samples like zircon. This study compares two distinct gravity separation methods, the Gemini Table and manual panning, to evaluate effectiveness in recovering dense mineral fractions. The Gemini Table utilizes a mechanical, tilted platform where water flows and induced shaking sort grains by density along grooves. In contrast, manual panning relies on the suspension of less dense materials in a shallow basin through hand-induced agitation until only the heavy minerals remain. Both methods were applied to a sandstone sample from the Freda Formation, a siliciclastic unit within the Midcontinent Rift. While the Gemini Table yielded a larger total volume of dense material, subsequent analysis revealed a lower concentration of zircon compared to manual panning. Higher panned recovery suggests that, despite its manual nature, panning may be more effective for mineral concentration. Beyond yield, the Gemini Table requires extensive cleaning of its complex surface to prevent cross-contamination, a time-intensive process. In contrast, manual panning was completed in half the time using only a basin and sink. These preliminary results suggest that for specific sandstone samples, manual panning provides a streamlined, time-efficient alternative for procuring high-quality zircon separates.
Per- and poly-fluoroalkyl substances (PFAS) are a collection of widely used contaminants, and have been coined as “forever chemicals” due to their long-lasting nature in the environment. Impacts on human health are thought to be associated with the development of cancers, thyroid issues, and reproductive issues. In 2024, PFAS were detected in exceedance of regulatory recommendations in several private wells in rural southwest Eau Claire County, leading to county-wide systematic testing.Between July 2024 and April 2025, student researchers at UWEC sampled 141 private wells for PFAS. Samples were analyzed at the Wisconsin State Laboratory of Hygiene. Samples collected by UWEC and the Eau Claire City-County Health Department detected PFAS in approximately 35% of the samples, with 19% exceeding the EPA limit of 4 ppt (parts per trillion) for PFOA. Visual inspection appears to show a correspondence between elevated PFOA and paper mill sludge spreading. There is not a clear indication of elevated PFAS corresponding with wastewater or septic land spreading. There is no clear relationship between elevated PFAS and exceedances in other water quality parameters, including nitrate.
