Field Trips
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Field Trips

Post-Meeting

NOTE: Some post-meeting trips have been canceled. [ view trips ]

429. Crustal Evolution of Archean Rocks from the Minnesota River Valley: Geologic, Geochronologic, and Isotopic Constraints.
Wed.–Fri., 12–14 Oct. US$272 (L, R, 2ON).
Leaders: Robert L. Bauer, Univ. of Missouri; Marion E. (Pat) Bickford; David L. Southwick; Aaron Satkoski; Scott Samson.

Trip Description
The granite-gneiss terrane exposed in the Minnesota River Valley of southwestern Minnesota displays a complex history of deformation, high-grade metamorphism, and igneous intrusion ranging from the Paleoarchean to the Paleoproterozic era. Classic geochronologic studies of the Morton and Montevideo gneiss, using Rb-Sr and bulk U-Pb zircon analyses, recognized the complexity and antiquity of the terrane. However, recent high-resolution SHRIMP U-Pb analyses have demonstrated well-defined events at ca. 3.5, 3.38, 3.34, and 2.6 Ga that link the development of the gneiss terrane across several structural blocks, culminating in its accretion to the southern margin of the Superior Province along the Great Lakes Tectonic Zone. Further, Hf and Nd isotopic studies have shown that the entire terrane remained essentially a closed system during repeated melting, remelting, and metamorphic events until the emplacement of the Sacred Heart granite at 2.6 Ga. This trip will examine each of the major rock units exposed within the corridor between Morton and Montevideo, Minnesota, to provide a lithologic, structural, and metamorphic context for the recent dating and isotopic studies. Features examined will include complex migmatitic and deformation features of the Morton and Montevideo gneisses, granulite facies metamorphic assemblages in deformed metapelitic units, Neoarchean granitic intrusions, and late-stage Paleoproterozoic mafic dikes. Units and features will also be discussed in their regional tectonic context.
Leader Info
Primary leader email:
Primary leader bio: Bob Bauer has worked on structural, metamorphic, and tectonic problems in Precambrian terranes for over 40 years. He taught at Macalester College in St. Paul, Minnesota, from 1977 to 1982 and has been on faculty at the Univ. of Missouri since 1982. From 1992 to 2010, Bauer ran the Univ. of Missouri’s geology field course, located near Lander, Wyoming.
Primary leader experience: Bauer has conducted field studies and run field trips in the Minnesota River Valley (MRV) for many years, beginning in the mid-1970s, and he was a co-author on one of the recently published radiometric dating papers in the MRV.

435. Hydrostratigraphy of a Fractured Urban Aquitard.
Thurs., 13 Oct. US$85 (L, R).
Leaders: Julia Anderson, Minnesota Geological Survey; Anthony Runkel; Robert G. Tipping; Kelton Barr; E. Calvin Alexander.

Trip Description
This one-day trip will provide an overview of the hydrostratigraphic attributes of the Platteville aquitard in the Twin Cities Metropolitan area. As a shallowly buried, extensively fractured and therefore vulnerable carbonate rock in an urban setting, the Platteville has been the subject of a wide variety of geomechanical and hydrogeologic studies over the past few decades. This work, combined with our own borehole geophysics and outcrop observations, has led to a comprehensive understanding of the Platteville. The field trip will provide examples of what we have learned from these many different data sources, which collectively lead to a characterization of the Platteville as a complex “hybrid” hydrogeologic unit. Under certain conditions, and from one perspective, it can serve as an important aquitard that limits vertical flow, while in other conditions, and from another perspective, it is best considered a karstic aquifer with conduits of very high conductivity that permit rapid flow of large volumes of water. One particular focus of the trip will be demonstration of what appears to be predictability in both vertical and bedding-plane fracture patterns that in turn provides some degree of predictability of flow paths in three dimensions. These relationships appear to be operative for the Platteville in other portions of the Upper Midwest where the Platteville is shallowly buried. We will demonstrate that effective management of such complex, karst, "hybrid" hydrogeologic units requires a sophisticated, nuanced understanding of their heterogeneous behavior.
Leader Info
Primary leader email:
Primary leader bio: Assistant scientist at the Minnesota Geological Survey, Newton Horace Winchell School of Earth Sciences, University of Minnesota, 2008 to present. B.A. geology, Gustavus Adolphus College, 2006; M.Sc. geology, Idaho State University, 2008.
Primary leader experience: My research interests include Paleozoic bedrock stratigraphy of Minnesota, carbonate depositional environments on the mid-continent shelf, and characterizing the hydrostratigraphic attributes of these strata to understand the manner in which ground water travels trough matrix and secondary pores. Current projects include mapping Paleozoic bedrock geology and bedrock topography of Southeastern Minnesota and defining the hydrostratigraphic properties of these units, including extensive research on the Platteville Formation. I have two publications on these topics, one in press, and several abstracts.

438. Groundwater–Surface-Water Exchange and Geologic Setting of Northern Minnesota’s Lakes, Wetlands, and Streams: Modern-Day Relevance of Tom Winter’s Legacy.
Thurs.–Fri., 13–14 Oct. US$188 (L, R, 1ON).
Cosponsors: GSA Divisions: Hydrogeology; Limnogeology; Quaternary Geology and Geomorphology.
Leaders: Donald Rosenberry, U.S. Geological Survey; David R. Lee; Perry M. Jones; Kelton D. Barr; Robert Melchior.

Trip Description
Tom Winter began his 50-year career with USGS studying groundwater–surface-water interaction in Minnesota. Quantifying exchange and understanding processes at this ecotone was societally relevant then just as it is today. This two-day field trip will retrace some of Tom’s steps by recounting research conducted during the 1960s and 1970s and highlighting ongoing research in response to current water-resource concerns. Exceptionally high or low water levels in response to drought and deluge continue to plague property owners and water-resource managers, prompting studies related to causes, ramifications, and solutions. Several stops will demonstrate the effect of multi-year drought on lake and wetland resources and highlight past and current research into the causes of these extreme conditions. Mining is once again on the increase in Minnesota, just as it was when Tom began his career. A stop in the mining district of Minnesota will highlight the potential influence of mine dewatering on surface-water resources and water-quality concerns associated with proposed nickel/copper/platinum-group mining in the Duluth complex. The influence of climate change on Minnesota’s water resources is best documented with long-term investigations. Research at the Shingobee headwaters field site established by Tom in 1978 is now in its fourth decade, prompting a tour of the infrastructure and an overview of scientific advances stemming from interdisciplinary collaboration at the site. Tom Winter always related hydrology to geologic setting; we will do the same, stopping to discuss some of the most prominent and scenic geological features that north-central Minnesota has to offer.
Leader Info
Primary leader email:
Primary leader bio: Donald Rosenberry is a research hydrologist with the USGS National Research Program in Denver, Colorado, specializing in processes that affect exchange between groundwater and surface water and developing new tools for quantifying fluxes at the sediment-water interface. Don received his training in geology, geography, hydrogeology, and fluvial geomorphology at Bemidji State Univ., Univ. of Minnesota, and Univ. of Colorado. Don has been a member of MGWA since 1984, is a GSA Fellow, and travels frequently to Minnesota to collaborate with colleagues and conduct research at the USGS Shingobee Headwaters field site between Walker and Park Rapids.
Primary leader experience: Knowledge of field trip areas and familiarity with Tom Winter’s life-long research.

439. Geology and Sedimentology of the Paleoproterozoic Animikie Group: The Pokegama Formation, the Biwabik Iron Formation, and Virginia Formation of the Eastern Mesabi Iron Range, and the Thomson Formation near Duluth, Northeastern Minnesota.
Thurs.–Fri., 13–14 Oct. US$242 (B, L, D, R, 1ON).
Leaders: Richard W. Ojakangas, Univ. of Minnesota–Duluth; Mark J. Severson; Peter K. Jongewaard.

Trip Description
This field trip will take place on the world-famous Mesabi Iron Range. Stops will be in the three formations of the Paleoproterozoic Animikie Group—the Pokegama Formation, the Biwabik Iron Formation, and the Virginia Formation, as well as the Archean basement. The rocks are reasonably well-exposed despite a cover of glacial deposits. The Mesabi was very instrumental in the development of Lake Superior–type iron formation, one of the two main types of Precambrian iron formation. Also, the Mesabi was instrumental in making the U.S. an industrial giant and in the winning of WWI and WWII. The final stop will be in the Thomson Formation (correlative with the Virginia Formation) ~60 miles south of the Mesabi.
Leader Info
Primary leader email:
Primary leader bio: Professor emeritus, Dept. of Geological Sciences, Univ. of Minnesota–Duluth, Minnesota. Ojakangas conducted teaching and research for 38 years, specializing in sedimentary rocks, with an emphasis on the ore deposits that they contain, e.g., iron, uranium, gold. He spent 22 summers with the USGS and/or Minnesota Geological Survey.
Primary leader experience: The primary leader has been a co-leader on many field trips in this region and has spent considerable time working on these rocks in the field.

441. Sudbury Meteorite Impact Layer in the Western Lake Superior Region.
Thurs.–Sat., 13–15 Oct. US$363 (B, L, D, R, 2ON).
Cosponsor: GSA Planetary Geology Division.
Leaders: Mark A. Jirsa, Univ. of Minnesota; Philip Fralick; Paul W. Weiblen; Jennifer L.B. Anderson.
This trip will cross into Canada; passports required.

Trip Description
This trip examines a sequence of ejecta and deformed substrate resulting from the 1850 Ma Sudbury meteorite impact. Of the 178 verified terrestrial impacts, the Sudbury event was the second largest (based on estimated crater size) and forth oldest. An impact origin for the Sudbury structure in Ontario has long been accepted; however, the resulting ejecta blanket was discovered only recently (in 2005) and was informally named the "Sudbury impact layer." In the western Lake Superior region, the layer lies at the stratigraphic top of Paleoproterozoic Gunflint Iron Formation, 700 km west of the impact site. The trip will visit exposures at Gunflint Lake in NE Minnesota, at the edge of the Boundary Waters Canoe Area Wilderness, and near Thunder Bay, Ontario. The deposits include autochthonous material interpreted to be seismically folded and shattered iron-formation, and overlying strata composed largely of allochthonous material derived in part from target rocks. Definitive evidence of an impact origin includes the occurrence of accretionary lapilli, pellets, spherules, relict glass, and quartz fragments marked by planar deformation features. The Sudbury impact layer exhibits extreme lithologic variability from place to place within each exposure area and between exposure areas, which is not surprising given the chaotic nature of impact. The stratigraphy presented by these exposures can be used to devise a sequence of deformational and depositional events that is consistent with experimental and empirical evidence of impact processes.
Leader Info
Primary leader email:
Primary leader bio: B.S., Univ. of Wisconsin (1976); M.S., Univ. of Minnesota–Duluth (1980); senior scientist for the Minnesota Geological Survey (1979–present). Jirsa’s work utilizes the combination of geophysical, geochemical, and structural data acquired from drill core and outcrop to improve and convey the understanding of Minnesota’s Precambrian terranes. He has authored and co-authored more than 125 maps, publications, and abstracts. He is secretary-treasurer of the Institute on Lake Superior Geology (1994–present) and has been a field camp instructor for Precambrian Research Center, Univ. of Minnesota–Duluth from 2007 to present.
Primary leader experience: Jirsa has more than 30 years mapping and research experience, focused primarily on Precambrian terranes of the Canadian Shield and has been a leader and co-leader of many, many field trips.

442. Late Quaternary Landscape Dynamics beyond the Ice Margin in the Upper Mississippi Valley.
Thurs.–Sat., 13–15 Oct. US$342 (L, R, 2ON).
Leaders: Joseph A. Mason, Univ. of Wisconsin–Madison; Peter M. Jacobs; J. Elmo Rawling; Paul R. Hanson; Douglas J. Faulkner.

Trip Description
This field trip will focus on late Quaternary geomorphology and paleoecology in parts of the upper Mississippi River basin that were outside the limits of Late Pleistocene glaciations. The trip will highlight new insight from recent work, including abundant new geochronological data, but will also serve as a tribute to the career of Jim Knox (UW-Madison). A technical session with a similar theme will be proposed for the meeting. At sites in southeastern Minnesota and western Wisconsin, we will present evidence on the response of fluvial, eolian, and lacustrine systems to the dynamics of the nearby ice sheet and broader Late Pleistocene to Holocene climatic change. Topics covered at field trip stops will include (1) late Quaternary aggradation, incision, and paleohydrology of the Upper Mississippi itself and major tributaries such as the Chippewa, Root, and Kickapoo River systems; (2) plant macrofossils, gastropods, stable carbon isotopes, and other paleoecological evidence preserved in stream sediments and soils of southeastern Minnesota and western Wisconsin; (3) regional patterns of loess dispersal and dune activity and their environmental controls; (4) the stratigraphic record of Quaternary hillslope processes and the relative importance of glacial and nonglacial sediment supply to fluvial systems; (5) Glacial Lake Wisconsin and the preservation potential of coastal landforms in a periglacial environment.
Leader Info
Primary leader email:
Primary leader bio: Research interests: Geomorphology and soils, focusing on eolian and hillslope sediments and processes. M.S., Univ. of Minnesota (1992, Loess distribution and soil landscape evolution, southeastern Minnesota); Ph.D., Univ. of Wisconsin–Madison (1995, Hillslope response to glacial-interglacial climatic change, southeastern Minnesota); assistant professor, geography, Northern Illinois Univ. (1995–1997); assistant professor and research geologist, Conservation and Survey Div. and Geosciences, Univ. of Nebraska–Lincoln (1997–2003); assistant–full professor, geography, Univ. of Wisconsin–Madison (2003–present).
Primary leader experience: (1) I've done research on loess, eolian sand, colluvium, and fluvial deposits in southeastern Minnesota for over the last 21 years. I have a current NSF-funded project studying loess dispersal and the soil geomorphology of hillslopes and eolian sediments in southeastern Minnesota and southern Wisconsin. As a student and colleague of Jim Knox, I am familiar with his long-term research effort in the Wisconsin Driftless Area. I collaborated with research on paleoecology (plant macrofossils and gastropods) along the field trip route, and I'm also familiar with most recent work in Lake Wisconsin area. (2) Besides the research experience described above, I am very familiar with the entire field-trip route, having explored it to identify research sites and also conducting many class field trips in the area.

topCanceled post-meeting trips

430. The Baraboo District—An American Classic.
Wed.–Fri., 12–14 Oct. — Canceled.

431. Distal Signatures of Late Ordovician Oceanic Anoxia—New Data and Interpretations of a Classic Eperic Ramp Transect.
Wed.–Sat., 12–15 Oct. — Canceled.

432. Stratigraphy, Physical Volcanology, Hydrothermal Alteration, and Mineralization Associated with the Neoarchean Vermilion Greenstone Belt, NE Minnesota.
Wed.–Sat., 12–15 Oct. — Canceled.

433. The North Shore Volcanic Group: A 9-km-Thick Plateau Lava Sequence in the Mesoproterozoic Midcontinent Rift System.
Wed.–Sat., 12–15 Oct. — Canceled.

434. Late Glacial History of the Western Lake Superior Region.
Wed.–Sat., 12–15 Oct. — Canceled.

436. Enhancing Access to Fieldwork: A Participatory Exploration of Cave Geology for Mobility-Impaired Students.
Thurs., 13 Oct. — Canceled.

437. Retreat of the Laurentide Ice Sheet: Landforms, Sediments, Timing.
Thurs.–Fri., 13–14 Oct. — Canceled.

440. Anatomy of a Mineralized (Cu-Ni-PGE) Mafic System: the South Kawishiwi Intrusion of the Duluth Complex.
Thurs.–Sat., 13–15 Oct. — Canceled.

443. Copper Deposits of the Western Upper Peninsula, Michigan.
Thurs.–Sat., 13–15 Oct. — Canceled.

444. Layered Intrusions of the Duluth Complex.
Thurs.–Sat., 13–15 Oct. — Canceled.

445. Event History and Sequence Architecture of the Middle–Upper Devonian Epeiric Carbonate Platform of the Iowa Basin.
Wed.–Sat., 12–15 Oct. — Canceled.

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