Stratigraphic and Structural Interpretations of the Prairie du Chien Group, Western Wisconsin and Eastern Minnesota Samantha S. Taylor J. Brian Mahoney University of Wisconsin - Eau Claire Eau Claire, WI 54702 Abstract Analysis The Prairie du Chien group in western Wisconsin and eastern Minnesota is a Detailed stratigraphic analysis of the Oneota Formation of the Prairie du Chien Group in the Biesanz Stone Quarry in Winona, Minnesota was used to characterize the economically important components of the stratigraphy. large supplier of dimension stone. The durability of these blocks allows them to Lithologic and diagenetic characteristics were documented by detailed (1:100) analysis of quarry strata. Petrologic characteristics will be documented by thin section petrogrpahy. Major and trace element geochemistry be used in a wide variety of applications from small garden steps to large building was conducted via Sequential X-ray Fluorescence (XRF) Spectrometry at the University of Wisconsin - Eau Claire. stones. There are several different stratigraphic intervals in the Oneota Formation that are ideal for dimension stone, and identifying these intervals would increase Stratigraphy the production of stone in the Prairie du Chien region. Detailed stratigraphic analyses of the Oneota Formation in Winona, Minnesota are used to determine 22DP12 800 zones of stratigraphic intervals of economic importance. The Oneota Formation is a cliff forming sandy dolomite that forms the bluffs along the Mississippi River. 25 21DP12 Petrologic and geochemical analysis have been conducted to determine the vug 700 19DP12 Levee (110cm) density and sand content. These data are essential in dividing the group into E separate members and determining the lateral and vertical variations within members. 600 20DP12 18DP12 Yellow (285cm) ^ 5 ^ 6 Contact between Pink and 10’ layers. Top of 20’ unit, below White Layer. Introduction Levee (110 cm) Note dense base gradationally overlain by vuggy interval Note bedding parallel vugs and alteration zone along upper contact 19DP12 500 Dolomite from the Oneota Formation is ideal for a variety of applications in 20 construction and landscaping, and has been mined at the Biesanz Stone Quarry in 17DP12 Winona, MN for over 100 years. Expansion of the quarry requires identification 18DP12 Yellow (285 cm) 400 of high quality materials in the subsurface in adjacent leases. Detailed analysis of 17DP12 16DP12 lithologic, petrologic, diagenetic and geochemical characteristics of quarry strata 15DP12 White Layer (41cm) will be used to assess the quality of materials in drill core from adjacent properties. 16DP12 15DP12 White Layer (41 cm) D ^ 6 Eventual correlation between the on-site stratigraphic sections and off-site drill 14DP12 20’ (57 cm) 300 14DP12 20’ (57cm) cores will serve as an essential reference for future mine expansion. 13DP12 10’ (25 cm) 12DP12 Pink (55 cm) 13DP12 10” (25cm) ^ 5 11DP12 12’ (10 cm) ^ 4 15 9DP12 12DP12 Pink (55cm) Terazzo (180 cm) 200 9DP12 11DP12 12’ (10cm) Local Uses ^ 3 ^ 3 ^ 4 Contact between unit C and D (Terazzo unit). Medium bedded birdseye dolomite with sandy Dimension stone from the Biesanz Stone Quarry is distributed nationwide for use 8DP12 Contact defined at the loss of thin sand beds and glauconite vug-fillingof Unit D (Terazzo unit) 7DP12 in construction as natural stone panels and finishing material. It can be seen gF/U 100 locally across Western Wisconsin and Eastern Minnesota in a wide variety of 9DP12 Terazzo (180cm) public and private buildings. Dimension stone from the Biesanz Stone Quarry F/U 50 was used extensively in the construction of the new W.R. Davies Student Center g ^ 2 0 on the UW - Eau Claire campus, and may be found as facing stone on the external 10 F/U walls of the building, on all eight large fireplaces, and forms the benches that g C cm create the outdoor amphitheater. F/U g

F/U 6DP12 g 5DP12 ^ 1 4DP12 5 Symbol Legend B g glauconite ^ 2 parallel laminae Sandstone/dolomite cycles of Unit C. 3DP12 cross bedding Note soft sediment deformation and glauconite horizons www.arnoldandosheridan.com F/U fining-upward cycle At the Acuity Insurance Headquarters in Sheboygan, WI, Biesanz Natural Stone 1 2DP12 siliceous nodules ^ 1 Panels were used to line the exterior of the building and Biesanz Minnesota Dolomite 1DP12 Cross-stratified quartz arenite of the upper Limestone (MDL) was used on the interior tile flooring, wall columns and stairs. A Jordan Formation, below transition zone. m 0

Geochemistry Regional Geology Hypothesis: Our intial hypothesis was that the quality of the dimension stone was fundamentally controlled by the quartz sand content and the percentage of vugs present in the units. Geochemically, an influx of quartz sand would be indicated Galena Fm. Trent. by an increase in SiO2, Zr, Sc, Ce and other trace elements. Conversely, a decreased sand content would lead to elevated Decorah Fm. MgO, CaO, Ba, Sr and other elements with an affinity for carbonate. Platteville Fm.

Glenwood Fm. CaO % MgO % SiO2 % Black 22 22 22 St Peter Fm. 21 21 21 www.christnerinc.com Hager City Mbr 20 20 20

Ordovician Shakopee Fm. 19 19 19 Oneota Formation 18 18 18 Goldfarb School of Nursing at Barnes-Jewish College in St. Louis, 17 17 17 MO utilized natural stone panels to create a prominent image for Oneota Dol. 16 16 16 15 15 15 their new nursing program. Coon Valley Mbr 14 14 14 Top of Economic Zone Trem. Jordan Fm. 13 13 13 12 12 12 St Lawrence Fm. 11 11 11 Franc. Lone Rock Fm. 10 10 10 Jordan Sandstone 9 9 9 Wonewoc Fm. 8 8 8 Base of Economic Zone 7 7 7 Cambrian Dresb. Eau Claire Fm. 6 6 6 Mt. Simon Fm. 5 5 5 4 4 4 Top of Jordan Sandstone Contact between the Cambrian Jordan Sandstone and the 3 3 3 Precambrian 2 2 2 Ordovician Oneota Formation. The Oneota Formation is 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 0.0 5.0 10.0 15.0 20.0 25.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 subdivided into two members: CoonValley and Hager City. Generalized stratigraphic column for Cambro-Ordovician strata in west-central Wisconsin Ba (PPM) Co (PPM) Pb (PPM) Rb (PPM) 22 22 22 22 21 21 21 21 20 20 20 20 19 19 19 19 18 18 18 18 17 17 17 17 16 16 16 16 15 15 15 15 14 14 14 14 Base of Yellow 13 13 13 13 Dolomite dimension stone being applied to the exterior of W.R. Davies 12 12 12 12 11 11 11 11 Student Center during construction in the Spring of 2012. 10 10 10 10 9 9 9 9 8 8 8 8 7 7 7 7 Base of Terazzo Generalized stratigraphic subdivisions 6 6 6 6 5 5 5 5 utilized in the Biesanz quarry to 4 4 4 4 Best (hardest) 3 3 3 3 classify different qualities of 2 2 2 2 Fractured Rock Crushed Varies building stone. Note the ‘productive 0 20 40 60 80 100 120 140 160 0 10 20 30 40 50 0 5 10 15 20 25 30 0 5 10 15 20 25 30 Aggregate zone’ consists of several different discrete intervals based on hardness Sr (PPM) Y (PPM) Zn (PPM) Zr (PPM) 24” - 36” Levee Ledge Softer Stone 22 22 22 22 and durability that determine 21 21 21 21 20 20 20 20 the primary use. 19 19 19 19 18 18 18 18 17 17 17 17 Waste Material 16 16 16 16 10’ ± Fractured Rock 15 15 15 15 14 14 14 14 Base of Yellow Landscape material 13 13 13 13 12 12 12 12 or veneer 11 11 11 11 10 10 10 10 9 9 9 9 12” White Ledge Thicker Uses - 8 8 8 8 7 7 7 7 Base of Terazzo 20” - 30” 20” Ledge Dimensional Stone 6 6 6 6 5 5 5 5 10” - 14” 10” Ledge 4 4 4 4 Wall Rock 3 3 3 3 Sand Indicator 18” - 36” Pink Ledge Biesanz Panel - sawed thin 2 2 2 2 0 20 40 60 80 100 120 140 0 2 4 6 8 10 12 14 16 0 20 40 60 80 100 0 10 20 30 40 50 60 70 80 Dolomite Indicator 12” - 18” 12” Ledge BEST STONE Sometimes landscaping Conclusions: The geochemical data gathered from stratigraphic samples confirmed the assumption that the quality of the 24” - 48” Terazzo Ledge dimension stone is at least in part controlled by the amount of quartz sand in the strata. Note that both major and trace Generally not quarried Upper Ordovician - Limestone, shaley limestone, and dolostone. element geochemical plots display a critical elemental shift at the base of the productive zone (Terazzo Ledge). Note the Middle and Upper Ordovician - Shale, dolomitic limestone, and sandstone. distinct increase in MgO, CaO, Ba, and Sr. and decrease in SiO , Zr, Sc, Ce, reflecting a decrease in the clastic component. Fractured Rock 2 Lower Ordovician - Dolostone, sandy to silty dolostone, and sandstone; includes the Shakopee Formation and A transition zone of integrated sandstone and dolomite can also be observed stratigraphically below the indicated 45’ - 50’ ± Too soft to make Oneota Dolomite of the Prairie du Chien Group. Sand Rock switch in systems. good aggregate Upper Ordovician - Sandstone, siltstone, and dolostone; includes the Jordan Sandstone Contact between the Coon Valley Mbr and the Hagar City Mbr in the Biesanz Quarry. Note the Middle and Upper Cambrian - Sandstone, siltstone, and shale; includes Eau Claire Formation and Mt. Simon Sandstone Acknowledgments: This project is a collaborative effort between the Department of Geology at the University of Wisconsin-Eau Claire and the Biesanz Stone Company. Pete Schwab of Biesanz Stone Company is saw cuts used to extract stone from the quarry. thanked for project oversight and quarry access. Darrell Reed of SEH, Inc., is thanked for project management and access to drill core.