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Geological sciences.

A Survey of the Geologic Histories of Allegan County Bogs. Suzanne DeVries-Zimmerman and Edward C. Hansen, Hope College

We investigated three Allegan County bogs to determine their stratigraphies and geologic histories and to look for regional patterns in these histories. We collected sediment cores in one-meter intervals from the surface down to the lowermost sand layer. We made smear slides every 15 cm along the core and estimated percentages of clastic, authigenic, and biogenic components, organic matter, and aquatic amorphous organic matter to determine the core's composition and to establish where changes in the core's composition occurred. Glacial lake plain sand underlies all three bogs indicating that each bog began as a small, shallow lake formed in shallow depressions left by the retreating glaciers. In two bogs, a rich fen, indicated by the presence of marl, developed. Algal gyttja deposition initially occurred in the third bog and then was followed by marl deposition. The marl deposition was succeeded by the development and accumulation of aquatic peat, probably dominated by sedges. Eventually, enough aquatic peat was deposited to raise part of the mound above water. A Sphagnum-rich bog then developed on this emergent surface, causing the deposition of peat. Currently, these bogs are each dominated by a Sphagnum- and heath-rich bog community.

Analysis of Phosphates in Sediments. Kristen H. Hasbrouck, Daniel S. Anderson, Kathy M. DeBlasio, Lucas B. Johnson, Daniel P. Pesch, and Graham F. Peaslee, Hope College

The main purpose of this project is to determine phosphate levels in suspended sediment samples collected from the Macatawa Watershed in Allegan and Ottawa counties in Western Michigan. Analysis of phosphate levels is relevant to this watershed because it has been determined previously that phosphorus is the limiting reagent in eutrophication; higher levels of phosphates lead to increases in eutrophication, which can cause algal blooms. By studying the phosphate levels in sediment, the locations of problem sites within the watershed that are contributing higher amounts of aqueous phosphates will be determined. Phosphate analysis was done using a SEAL AutoAnalyzer III -continuous flow injection colorimetric method. Phosphates are first extracted from collected sediment samples using dilute solutions of potassium chloride, sodium hydroxide and hydrochloric acid to remove water-soluble, iron-bound and calcium-bound phosphates respectively. Together these concentrations give the bioavailable phosphate that contributes to eutrophication. Preliminary results will be presented which show varying levels of phosphates in suspended sediments in different subwatersheds. They will also be compared with elemental composition analyses of the sediments that show a correspondence with iron and calcium binding in the suspended sediments.

Cathodoluminescent Signatures of Neutron Irradiation. Danielle K. Silletti, Sarah A. Brokus, Elly B. Earlywine, Joshua D. Borycz, Graham F. Peaslee, Hope College and JoAnn Buscaglia, FBI CFSRU

Nuclear proliferation and the potential threat to national security from unsecured special nuclear (SNMs) materials have renewed our national interest in detecting the presence of these materials. Currently, the only method to identify where SNMs have been stored involves measuring induced radiation in adjacent materials, which is usually short-lived. We have identified a permanent change to the luminescent properties of certain common minerals that is due to neutron irradiation that could potentially be developed into a nuclear forensics tool.

Feldspars and carbonates are ubiquitous minerals that are known to luminesce under electron bombardment. The UV-Visible spectra of hundreds of individual feldspar and calcite grains were measured with cathodoluminescence (CL) spectroscopy before and after neutron irradiation. CL excitation uses an electron beam to induce fluorescence in certain minerals due to their chemical composition and defects in their crystal lattice structure. The presence of ionizing radiation causes additional crystal lattice defects that leave a permanent CL signature. Dose-response results from a neutron source study and a reactor study will be presented. There is also an orientation dependence in the luminescence measurement technique that complicates the analysis, but when fully understood could allow the total dose to be estimated.

Cesium-137 Profiles in Post-settlement Alluvium, Eastern Ottawa County, Michigan: Is Alluvium a Significant Carbon Sink in Terrestrial Ecosystems? Patrick M. Colgan, Kent A. Walters, and El Elizabeth C. Koeman, Grand Valley State University

We estimate the rate of organic carbon storage in post-settlement alluvium since 1963-1964, in eastern Ottawa County, Michigan using laboratory methods and cesium-137 dating. Percentage of organic carbon is determined by using the loss on ignition method for approximately 200 alluvium samples from soil sections and vibracores. Organic carbon percent varied widely in these hetereogenous alluvial sediments. Mean organic carbon content was 4.1 [+ or -] 2.0% by mass for post-settlement alluvium. We estimate a mean mass organic carbon in the upper meter of ~54 kg/m3. Samples from two vibracores were then analyzed for cesium-137 produced by bomb testing in the 1950s and 1960s. Cesium-137 peaks were found at depths of approximately 188 [+ or -] 63 mm and 360 [+ or -] 120 mm. The cesium-137 data indicate alluvial deposition rates of 4.0 [+ or -] 1.3 mm a-1 and 7.7 [+ or -] 2.6 mm a-1 for the two cores since 1963-1964. Combining these rates with estimates of mass of organic carbon in alluvium we find that the organic carbon storage rates are 0.22 [+ or -] 0.07 kg a-1 and 0.44 [+ or -] 0.14 kg a-1 in two cores since 1963-1964. This suggests and supports previous hypotheses that recent alluvium is a significant terrestrial carbon sink.

Chamber Filling of Ammonites. Gerald K. Van Kooten, Calvin College

Late Cretaceous ammonites from southern Alaska were used to evaluate mechanisms for sediment filling of ammonite chambers. Ammonite fossils from many areas have shell chambers filled or nearly filled with sediment. Passive diffusion of sediment into closed ammonite chambers is unlikely due to sediment plugging of the ammonite siphuncle and lack of fluid through flow. Passive diffusion should produce fine and delicate laminations, features not observed.

It is proposed that pressure pumping related to diurnal tides is a dominant chamber-filling mechanism. Active pumping would produce heterogeneous and disrupted fill material, a texture observed in polished ammonite slabs, and explains the presence of fine sand grains in filled chambers. Boyles Law predicts a 3 meter tide would induce a 2.5% volume change at 100 meters water depth by compression and decompression of gas in ammonite chambers.

Lab experiments which mimic a 3 meter tidal change show suspended sediment fills chambers very slowly, and sediment filling proceeds from the Last chamber back towards the first. It is likely that most chamber filling occurs during burial of ammonite shells in soft and water saturated sediment. Tidally induced pressure changes then force a sediment slurry into empty chambers.

Charcoal Abundance in a Peat Bog from Allegan County, Southwest Michigan: Paleoenvironmental Implications. Dean Hazle, Edward Hansen, and Suzanne DeVries-Zimmerman, Hope College

Charcoal abundances in sediment cores may indicate frequency and intensity of fire. Charcoal abundances were examined in a section of core from a peat bog in Allegan County Michigan. Other paleoenvironmental proxies determined from the same core include organic-bulk density, sand concentrations, plant macrofossils, and siliceous microfossils. There is a rough correlation between charcoal abundances and sand concentrations in the upper part of the section. An absence of aquatic siliceous microfossils suggest that during this period the bog was emergent. Thus, wind would have been the main mechanism by which sand and charcoal were transported into the bog. Increases in both fire and windblown sand may have been controlled by the same climatic factors: possibly aridity. In the lower part of the section peaks in charcoal are closer together, corresponding to a general rise in the background concentration of sand. The presence of aquatic siliceous microfossils suggests that the center of the bog was not yet fully emergent. Before emergence material may have been washed into the bog as well as being blown in by wind. This difference in pathways into the bog may partially account for the difference in sand and charcoal patterns.

Evidence for Holoecene-age, Periodic Loess Deposition in an Interlobate Landscape, Southern Michigan. Michael Luehmann, Trevor Hobbs, and Randall Schaetzl, Michigan State University

This research examines the paleoenvironmental significance, and possible origins, of anomalous silty deposits in the Evart Upland--a dry and otherwise sandy, interlobate landscape in southern Michigan. Here, silty deposits occur in the bottom-centers of dry, sandy kettles. The lens-shaped deposits are dominated by fine and medium (10-25 gm) silt; the surrounding interlobate landscape is formed in medium and fine sand-textured outwash. The abrupt lateral edges of the silty deposits, and their unique textural properties relative to the surrounding landscape, suggest that the silts were not winnowed from kettle backslopes by water. Instead, we propose that the silty sediment originated as loess that was episodically deposited across the Evart Upland and later redeposited into the centers of kettle bottoms by wind and water. Evidence in support of this conclusion includes: (1) the siltiness of the sediment, set within an overall sandy landscape, (2) increased silt contents within the upper meter of the sandy soils on nearby geomorphically stable (flat) uplands, and (3) charcoal-rich paleosols in the silt deposits, pointing to discrete episodes of loess deposition interspersed with periods of soil formation. Radiocarbon ages on charcoal samples from nine of these paleosols range from 960 to 10,930 cal yrs ago.

Evidence for Loess on the Dowagiac Delta, Berrien Springs, Michigan. Randall J Schaetzl and Alex Shackleton, Michigan State University

We report on silty and fine-sandy sediment covering a section of a large, Pleistocene delta in Berrien County, Michigan. This delta, informally named the Dowagiac Delta, formed in a glacial lake impounded by the Laurentide ice sheet while it sat at the Charlotte moraine. Detailed information about the extent and timing of this lake is, as yet, unknown. Approximately 6 X 5 km in area, the delta is comprised of stratified, sandy sediment. In many areas, the flat delta surface is overlain by 50-75 cm of silty-sandy sediment, which we interpret as loess. Samples taken from 16 sites on the delta surface were analyzed for particle size distribution, and the resultant data mapped in a GIS. Our maps show that the loess gets increasingly silty toward the northern and northwestern parts of the delta surface, and that it is quite sandy at the distal edges of the delta. The distribution, thickness characteristics, and textural patterns of the Doawgiac Delta loess may reflect strong but variable winds at a time when the top-center of the delta was exposed, to capture loess, while its edges were still under water or exposed only for shorter periods of time, as lake levels fell.

Luminescence Studies of Feldspar Minerals and Implications for Forensic Geology. Sarah A. Brokus, Danielle K. Silletti, J. Mark Lunderberg, Joshua Borycz, Paul A. DeYoung, and Graham F. Peaslee, Hope College; Dyanne E. Cooper and JoAnn Buscaglia, FBI CFSRU

Feldspar minerals are the most common constituents of rock on this planet and, as such, are regularly encountered in sediment samples. Because these feldspar minerals are so ubiquitous, they often provide mineral identification rather than yielding a provenance determination or source-level association by traditional examination. One possible method to rapidly analyze large numbers of diverse soil samples involves measuring the luminescence of feldspar minerals among them, which could rapidly yield highly discriminating characteristics of the feldspars.

In this study, a variety of 42 feldspar samples of known provenance were examined by cathodoluminescence (CL) in conjunction with ion beam induced luminescence (IBIL). Previously reported luminescent centers (Mn2+ and Fe3+) were observed and their UV-Visible peak positions vary with stoichiometric changes in the Na-K-Ca composition of the feldspars as expected. Similarly, Si-0 and A1-0 lattice defect luminescence in the UV-Visible spectra were observed in addition to a previously unassigned IR luminescence. Additional analysis of the feldspar samples by x-ray diffraction (XRD), electron microprobe (EMP), micro x-ray fluorescence ([mu]XRF), and particle induced x-ray emission (PIXE) was performed in an attempt to determine the mechanism for the unassigned IR peak, as well as shifting within luminescent peak signatures.

Monitoring Sand Transport and Windflow Patterns During Major Wind Events in a Blowout Sand Dune on the Southeastern Shore of Lake Michigan. Brian Yurk, Edward C. Hansen, and Timothy J. Pennings, Hope College

In August, 2010, we began a long-term study of sand deposition/erosion and windflow in a blowout sand dune on the Lake Michigan coast near Saugatuck, Michigan. One objective of this study is to test the hypothesis that the majority of changes in dune morphology along the southeastern Lake Michigan shore are due to storm winds. The data will also be used to understand and predict changes in blowout morphology over time. The study includes regularly monitoring a permanent array of 211 deposition pins and an array of six anemometers and wind vanes that are deployed during major wind events to monitor changes in the blowout, which has a large northwest facing trough and smaller west and north west facing troughs. The initial test of the system came with a windstorm (gusts up to 30 m/s) on October 26-28, 2010. The rotation of storm winds from southwest to northwest changed the patterns of wind steering and deposition and erosion in the blowout. In this talk, we will present our initial findings from this site, including data from fall and winter 2010/2011.

Properties of Niveo-Aeolian Deposits as Factors of Wind, Snow Events, and Dune Topography in Hoffmaster State Park, Muskegon County, Michigan. Adam Koster, Christopher Maike, Ann Parkin, and Deanna van Dijk, Calvin College

The coastal dunes of Lake Michigan provide a distinctive location to study niveo-aeolian activity: the interactions between wind-blown snow and sand. Our study investigates niveo-aeolian deposition at three dune environments within P.J. Hoffmaster State Park: a foredune, a 10-meter high blowout dune, and a 60-meter high parabolic dune. Our goals were to investigate the chronology, spatial patterns and sediment characteristics of the niveo-aeolian deposits found at these three environments. From December 2010 through February 2011, we took weekly measurements of the spatial patterns of the niveo-aeolian deposits and their sediment supply areas. We utilized "snow"-pits to investigate the layering in the deposits and to collect samples for sediment analysis. Measurements of local conditions that influenced niveo-aeolian activity included on-site records of wind speed and direction. The results of this study show how the interactions between snow events, wind, and dune topography produce different patterns and scales of niveo-aeolian deposition. We hoped to compare the deposits in each of these environments in order to further understand how the type of environments effects the deposition of niveo-aeolian deposits.

Properties of Niveo-Aeolian Deposits as Factors of Wind, Snow Events, and Dune Topography in Hoffmaster State Park, Muskegon County, Michigan. Adam Koster, Christopher Maike, Ann Parkin, and Deanna van Dijk, Calvin College

The coastal dunes of Lake Michigan provide a distinctive location to study niveo-aeolian activity: the interactions between wind-blown snow and sand. Our study investigates niveo-aeolian deposition at three dune environments within Hoffmaster State Park: a foredune, a 10-meter high blowout dune, and a 60-meter high parabolic dune. Our goals were to investigate the chronology, spatial patterns and sediment characteristics of the niveo-aeolian deposits found at these three environments. From December 2010 through February 2011, we took weekly measurements of the spatial patterns of the niveo-aeolian deposits and their sediment supply areas. We utilized "snow"-pits to investigate the layering in the deposits and to collect samples for sediment analysis. Measurements of local conditions that influenced niveo-aeolian activity included on-site records of wind speed and direction. The results of this study show how the interactions between snow events, wind, and dune topography produce different patterns and scales of niveo-aeolian deposition. We hoped to compare the deposits in each of these environments in order to further understand how the type of environments effects the deposition of niveo-aeolian deposits.
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Publication:Michigan Academician
Geographic Code:1USA
Date:Mar 22, 2013
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