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SESSION NO. 27 locality, known as the Arlington Archosaur Site (AAS), occurs in exposures of the Woodbine Formation in Tarrant County. The AAS preserves components of a coastal delta-plain ecosystem, including dinosaurs, crocodyliforms, turtles, and lungfish. Feeding traces consist of pits, scores, and a puncture that occur on multiple turtle shell fragments and two dinosaur limb bones. These traces are attributed to a crocodyliform based on diagnostic bite marks and comparisons to the morphology of the AAS crocodyliform. Marks on shells suggest an inertial feeding strategy followed by crushing. Dinosaur bones come from juvenile individuals and the marks are consistent with traces produced during disarticulation of prey by living crocodylians. The feeding ecology implied by these traces is similar to that of modern generalist crocodylians inhabiting similar environments. Considering the number of diagnosable crocodyliform feeding traces, numerous shed crocodyliform teeth, and the comparative absence of feeding traces from other predators, the AAS crocodyliform is interpreted as the apex predator. In association with the vertebrate fossils, 150 coprolites were recovered, demonstrating cylindrical, spiral, and scroll morphologies. The cylindrical coprolites are interpreted as crocodyliform intestinal tract material while scroll morphologies are assigned to general reptilian and possible crocodyliform. The coprolites are not deformed, and retain their original shape. This is indicative of rapid burial in a low energy environment soon after defecation. In modern coastal plains, crocodylians live and feed together in regions referred to as feeding grounds. The coprolites, turtle shells, teeth, and archosaur remains were mapped within a single horizon, and were disarticulated. Their association is interpreted as evidence of a crocodyliform feeding ground. Crocodyliforms therefore are not only important predators in ecosystems but also played an important taphonomic role in the assembly of vertebrate remains from the surrounding community through the formation of feeding grounds. 27-10 11:20 AM Koy, Karen A. [218344] TAPHONOMY OF VERTEBRATES IN A TEMPERATE FOREST SETTING: A TIME- TRANSGRESSIVE SEQUENCE KOY, Karen A. and HELWIG, Zane, Biology, Missouri Western State University, 4525 Downs Drive, Saint Joseph, MO 64507, kkoy@missouriwestern.edu For the last four years, a juvenile pig carcass was placed near a prairie/forest boundary were placed within a forest-prairie border environment. In the summer of 2012 the four carcasses were recovered for examination. The skeletal remains were collected, cleaned and reconstructed in the lab. Missing and damaged bones were recorded and photographed. The major bone elements (skull, mandible, and long bones) were evaluated for taphonomic grade, using the Behrensmeyer evaluation criteria. The time-transgressive series showed the sequence of bone decay within a temperate forest setting. Bone decomposition for the two carcasses exposed the longest reached beyond Stage 5, with full destruction. The two least exposed carcasses did not advance beyond stage 3. The highest level of damage occurred in the head and scapula. These carcasses experienced faster bone weathering in a temperate setting compared to the setting in Amboseli National Forest, where the decay scale was originally developed. SESSION NO. 28, 8:00 AM Friday, 3 May 2013 T17. Special Poster Session on Undergraduate Research (Posters) Schneider Hall, Courtyard 28-1 BTH 1 Osman, Matthew [218434] δ18O AND δD FRACTIONATION TRENDS IN SURFACE SNOW ACROSS THE MATTHES- LLEWELLYN DIVIDE, JUNEAU ICEFIELD, ALASKA AND BRITISH COLUMBIA OSMAN, Matthew, Geology Department, Augustana College, 639 38th St, Rock Island, IL 61201, matthewosman10@augustana.edu and MARKLE, Bradley, Department of Earth and Space Sciences, University of Washington, 4000 15th Avenue NE, Seattle, WA 98195 A lack of understanding of parameters that govern stable isotope fractionation in precipitation in regions of particularly complex meteorological conditions and high relief has long presented problems for paleoclimate and hydrologic studies. With a goal of obtaining high resolution data of local orographic effects on isotopic variation in precipitation, 123 surface snow samples were taken at 0.5 to 1 km increments along a 35 km transect spanning the Matthes and Llewellyn glaciers in southeast Alaska and British Columbia. These samples were obtained during late July to early August 2012 at elevations ranging from ~1260 m to 1870 m and were analyzed for δ18O and δD onsite using an LGR Liquid Water Isotope Analyzer. δ18O and δD were found to decrease with elevation, as expected. Isotopic plots show a strong correlation and are similar to the theoretical global meteoric water line, displaying a linear trend of y = 7.86x – 19.48 and r2 = 0.898. In hopes of determining the dominant types of localized weather systems causing these fractionation trends, results are compared alongside open-system Rayleigh fractionation models, NOAA back trajectory air-mass simulations, and nearby-recorded meteorological data. We attempt to place these weather systems into synoptic-scale meteorological contexts as a proxy for delineating orographic fractionation parameters on the Juneau Icefield. 28-2 BTH 2 Smith, Matthew D. [218611] TRACE ELEMENT CONCENTRATIONS IN SPELEOTHEMS FROM RIVER BLUFF CAVE, GREENE COUNTY, MISSOURI: PRELIMINARY RESULTS SMITH, Matthew D. 1 , JOHNSON, Aaron W. 1 , DORALE, Jeffrey2 , and MOTTALEB, M. Abdul3 , (1) Natural Sciences, Northwest Missouri State University, 800 University Drive, Maryville, MO 64468, s508653@mail.nwmissouri.edu, (2) Department of Geoscience, University of Iowa, 121 Trowbridge Hall, Iowa City, IA 52242-1379, (3) Natural Sciences, 800 University Drive, Maryville, MO 64468 River Bluff Cave in Greene County, Missouri contains numerous speleothems that have not been touched by humans. Speleothem ages range from 1.8 million years ago to the present, making it an ideal location in which to investigate recent climate variation. Speleothem samples were collected from two locations in the cave. Powdered carbonate samples were collected by dental drill from growth zoning visible in the cross section of the speleothems. Sample masses ranging from 11 to 27 mg were dissolved in aqua-regia and analyzed for Ba, Co, Cu, Fe, Mg, Mn, Pb, Sr, and Zn, using ICP-OES. Total metal concentrations were adjusted for dilution during dissolution and are reported here as micrograms metal per gram of sample (ppm). Trace metal concentrations varied widely. Barium, copper, and zinc were not found to occur at concentrations above the detection limit. Lead occurred only intermittently, ranging from 0 to 60 2013 GSA Abstracts with Programs 44.1 ppm. Other metals present include (in ppm): cobalt (0.3-113); iron (6.56-80.7); magnesium (93.5-151.5); manganese (0.17-1.99); and strontium (9.3-24.0). Studies indicate that variations in magnesium, iron, and strontium concentrations may be used to infer relative changes in the volume of water moving through the cave system. Since most cave water is meteoric in origin, these variations may indicate wetting or drying climates. The relationship to concentration is inverse for magnesium and strontium and direct for iron. Samples from River Bluff cave show an increase in Sr and corresponding decrease in Fe, indicating drying over the time period during which speleothem growth occurred. Mg concentrations do not exhibit a similar trend, likely due to thermal variation which changes the mg-calcite partitioning coefficient. In addition, samples exhibited spikes in Pb and Co concentrations. These spikes may be the result of high flows which tend to enrich metals that commonly are associated with colloids. Both Pb and Co may be adsorbed to the surfaces of clays or as amorphous metal oxides that can be mobilized during high water flow events. These data hint at an overall climate drying event punctuated by periods of increased moisture. The next step will be to link these data to geologic ages and to stable isotope compositions in an effort to account for the impact of temperature change on speloethem chemistry over time. 28-3 BTH 3 Kuhn, Ryan M. [218515] TRACE ELEMENT DISTRIBUTION IN PRECIPITATES FORMED AT VARIOUS PH VALUES: GREEN VALLEY COAL MINE, INDIANA KUHN, Ryan M., SEANEY, Derek L., BRAKE, Sandra S., BURCH, Kyle R., and LATIMER, Jennifer C., Department of Earth and Environmental Systems, Indiana State University, Terre Haute, IN 47809, rkuhn1@sycamores.indstate.edu This study evaluates the distribution of trace elements in precipitates formed from acid mine drainage (AMD) adjusted to various pH levels. AMD was collected from the Green Valley abandoned coal mine site in western Indiana from three locations (upper, mid-, and lower sections) in a constructed channel lined with carbonate rip-rap. Effluent pH at the sampling sites was 3.8, 3.5, and 3.4, respectively. The AMD was transported on ice to the laboratory and initially treated with hydrogen peroxide to oxidize ferrous Fe to ferric Fe. Sodium hydroxide was then titrated into the AMD solutions from each site to incrementally increase pH to induce precipitation. Samples were centrifuged to separate precipitates and aggregated into 1 pH increments. Dried, powered precipitate samples were analyzed using a hand-held X-ray florescence (XRF) analyzer. Elements detected above the analytical detection limit in order of abundance were S>Fe>Al>C a>Mg>Mn>Si>Cl>Zn>K>Cr>Ba>Cu>W>Ti>V>Te>Cs>Co>Sc>Nb>Sn>Bi>Sr>Ni>Cd>Mo>Sb> Zr>Rb>Pb>U. Data indicate that S, Al, Ca, Si, Cl, K, Cr, Cu, Ti, V, Sr, and Rb were detected in precipitates that formed over the entire tested pH range from 3 to 12. Iron, Ba, Te, Cs, Sn, Bi, and Sb showed peak co-precipitation/adsorption in precipitates forming at pH
the leading edges of an artificial lava flow poured out from a furnace to create a solid barrier to contain and ultimately stop the flow. For our numerical modeling, we are using a modified Navier-Stokes equation to account for the non-uniform temperature profile throughout the lava flow, in combination with a simplified heat flow equation to determine how the physical properties of the flowing lava might be affected by varying the cooling rates. Those equations, however, use simplified assumptions such as radial flow of lava, uniform cooling rate, uniform flow rate, etc., which may not always hold true for reallife lava flows. We are testing those assumptions by changing the boundary conditions of our physical experiments, such as changing slope of the lava flow, using water or ice to induce nonuniform cooling rates, etc. We are also exploring how liquid rocks can be used as a medium for art. Despite the obvious beauty of natural lava flows, there are very few artists, notably the artists associated with the Syracuse University Lava Project, who are working with lava as a medium for sculpture. We are exploring the potential use of the molten rocks as an artistic material by letting molten rocks flow over other shaped materials. Our presentation will focus on the preliminary results of our numerical and physical models, and discuss potential ways to address lava flow hazards. We will also present lava in a new light as a sculptural medium to broaden the aesthetic vision of this powerful force. 28-6 BTH 6 Birren, Thomas H. [218109] GEOCHEMISTRY OF THE NICKEL LAKE MACRODIKE AND IMPLICATIONS FOR CU-NI SULFIDE EXPLORATION BIRREN, Thomas H., Carleton College, 300 N. College St, Northfield, MN 55057, birrent@ carleton.edu, HAILEAB, Bereket, Geology, Carleton College, One North College Street, Northfield, MN 55057, and GIBBONS, Jack, University of Arizona, Tucson, AZ 85721 1.1 billion years ago, the Nickel Lake Macrodike(NLM) intruded various Archean and Paleoproterozoic country rock units in association with failed Midcontinent Rift magmatism. The NLM is a member of the Layered Series of the Duluth Complex and was the conduit to the sulfidebearing South Kawishiwi Intrusion (SKI). The SKI and other related intrusions are currently the focus of fevered exploration and as the feeder dike to the SKI, the NLM is an area of important study. The NLM intruded in three main phases: a heterogeneous and locally sulfide-bearing troctolite phase, an oxide-gabbro phase, and a layered troctolite phase. The dike is roughly 1 km wide and extends northeast to southwest for 6 km through swamp and dense forest straddling the border of the Boundary Waters Canoe Area in northern Minnesota. Crustal contamination is the major source of sulfur in the sulfide deposits of the various intrusive suites in the Duluth Complex. The Paleoproterozoic Biwabik Iron Formation and the Virginia Formation (1.8 Ga) are incorporated as the main sources of sulfur. The goal of this study is to conceive a plausible model of country rock incorporation. Do trace element (specifically REE) values differ significantly between the three main phases of the Nickel Lake Macrodike? Assuming the parental magmas had the same initial values (North Shore Volcanic Group) can country rock incorporation be qualified? What are the consequences of these findings in aiding exploration for magmatic Ni-Cu ore deposits? Rock chemistry, particularly trace elements, indicates that the NLM became increasingly more evolved with each phase of intrusion. The heterogeneous troctolite exhibits greater crustal contamination than the earlier phases. Because this is the sulfide-bearing phase of the NLM, this indicates that REE analysis may be an effective tool in aiding exploration. 28-7 BTH 7 Targos, Courtney [218723] GEOCHEMISTRY AND MINERALOGY OF THE UBEHEBE VOLCANIC FIELD, DEATH VALLEY TARGOS, Courtney1 , HUYSKEN, Kristin T. 2 , and KNIPE, Dawn2 , (1) Department of Geosciences, Indiana University Northwest, 3400 Broadway, Marram Hall, Room 243, Gary, IN 46408, cattargos@att.net, (2) Department of Geosciences, Indiana University Northwest, 3400 Broadway, Gary, IN 46408-1197 The Ubehebe Volcanic Field is located in northern Death Valley occupying an area of about 3 km2 . The area contains at least twelve recognizable volcanic craters that formed through phreatomagmatic eruptions, some of which dissect previously formed cinder and spatter cones. Eruption of the youngest, largest crater (Ubehebe; 700-800 m wide, 235 m deep) blanketed the crater rim and surrounding area (15 km2 ) with at least 50 layers of basaltic scoria and ash. Recent research has put the timing of the eruptions between 0.8 and 5.1ka and relates them to the local groundwater table. However, while they have been classified as basalts, there has been very little work focused on the geochemical variation of the rocks that make up the volcanic field. Samples were collected from three craters in the southern cluster. Among our findings are mineralogical and textural differences from crater to crater, including disequilibrium features in orthopyroxene phenocrysts and quartz xenocrysts. Major and trace element analysis of 22 basalt samples is currently underway to determine the complete compositional range, and whether compositional differences exist among these three craters with the goal of understanding the nature of the magma and the geologic processes that operated when this volcanic field was produced. 28-8 BTH 8 Henderlong, Peter J. [218554] COMPARING THE CHEMISTRY OF THE ELZEVIR BATHOLITH TO THE WESLEMKOON AND NORTHBROOK BATHOLITHS, ONTARIO, CANADA HENDERLONG, Peter J., Dept. of Geosciences, Indiana University Northwest, 3400 W. Broadway, Gary, IN 46408, phenderl@umail.iu.edu and HUYSKEN, Kristin T., Department of Geosciences, Indiana University Northwest, 3400 Broadway, Gary, IN 46408-1197 The Elzevir Batholith is located about 200 km northeast of Toronto, ON, Canada. It is part of a suite of tonalitic batholiths that intruded approximately 1270 Ma as part of a magmatic arc. Similar ages and major element compositions have led studies to suggest that these batholiths may be petrogenetically related. The purpose of this study is to compare new data from the Elzevir to already published data from earlier works and to compare the composition of the Elzevir to the nearby tonalitic batholiths in the suite. Eleven samples were analyzed to find major oxide and 11 trace element concentrations using X-Ray Fluorescence (XRF). Our major oxides lie on the same chemical trend as the published data, but have a narrower range (67.50 - 71.45 wt.% SiO compared with 64.76 - 75.70 wt.% SiO 2 2 for published values). The Elzevir samples show the greatest similarity to the Weslemkoon batholith located directly north. When comparing the Elzevir and Weslemkoon Batholiths, the major oxides show chemical similarities. However, elements Zr, Zn and Ti present differences between the two batholiths. Our Elzevir samples occupy a compositional gap that exists in the Weslemkoon. Most of the published data matches a lower Zr compositional trend also found in the Weslemkoon samples. The Elzevir and Northbrook Batholiths have chemical similarities with respect to major oxides. However, Elzevir data have lower Sr concentrations relative to the Northbrook. Rb/Sr ratios also show a distinct division between the batholiths. SESSION NO. 28 Elzevir samples are currently being analyzed for 29 trace elements using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). These analyses will help further distinguish between the Elzevir and surrounding batholiths. The Weslemkoon and Northbrook batholiths can be distinguished from one another based on trace elements Sm, Y, Nb and Th. We anticipate our results will allow us to determine how the Elzevir compares. 28-9 BTH 9 Conner, Jeremy [218778] AMS AND IMAGE ANALYSIS DATA AT MULTIPLE SCALES SUPPORT A MULTIPLE SHEET EMPLACEMENT MODEL FOR THE MAIDEN CREEK SILL, HENRY MOUNTAINS, UTAH CONNER, Jeremy, Earth & Atmospheric Sciences, Central Michigan University, 314 Brooks Hall, Mount Pleasant, MI 48858, conne2jm@cmich.edu, MORGAN, Sven, Department of Earth and Atmospheric Sciences, Central Michigan University, 314 Brooks Hall, Mount Pleasant, MI 48859, STUDENT, James J., Earth and Atmospheric Sciences, Central Michigan Univ, 314 Brooks Hall, Mt. Pleasant, MI 48859, and HORSMAN, Eric, Dept. of Geological Sciences, East Carolina University, Greenville, NC 27858 Anisotropy of Magnetic Susceptibility (AMS) and image analysis data have been used to investigate possible contacts across magma sheets in the Maiden Creek Sill (MCS) from the Henry Mountains, Utah, USA. Thirty-one cores were drilled along an 8 m vertical traverse on the margin of the sill. The MCS is composed of at least two sheets which are locally divided by a thin sliver of sandstone. The AMS data illustrate there is an abrupt 10x change in magnetic susceptibility (K) across the sheet-on-sheet contact where the sandstone sliver is absent. This contact is also defined by a 1-2 cm thick solid-state shear zone. There are also several “drop offs” (~10x) in K possibly indicating several different sheets, or contacts at lower levels. The magnetic foliation changes from subvertical to subhorizontal at the sheet-on-sheet contact. To further investigate the Shape Preferred Orientation (SPO) of the minerals, and to determine the controls on the magnetic foliation, image analysis was done using the Auto-Correlation Function (ACF) and Intercepts method. We used the 3rd contour of the ACF image, which correlated with the finer grains, to calculate the SPO and we used cm-scale images to determine the SPO using intercepts. These SPO’s conflict with the AMS foliation data although we are continuing to collect more SPO data at different scales to determine which grain size carries the AMS foliation. The AMS foliation data are consistent with multiple sheets being emplaced and possibly reflects a bull-dozer track-like emplacement model. Further research on the AMS and image analysis is being conducted to test emplacement models. 28-10 BTH 10 Elson, Joshua D. [218746] EDMAP-SUPPORTED GEOLOGIC MAPPING OF THE JANE QUADRANGLE, MCDONALD COUNTY, MISSOURI ELSON, Joshua D., CAUTHON, Matthew J., and EVANS, Kevin R., Geography, Geology, Planning, Missouri State University, 901 S. National, Springfield, MO 65897, jde419@ live.missouristate.edu The Jane quadrangle is located in south-central McDonald Co., Missouri, in the southwest corner of the Springfield Plateau. This project updates an earlier, incomplete geologic map published in 1959. Our map is based on more than 800 data points collected using a handheld GPS aided with the use of a stratigraphic column measured along US Hwy 71. The resulting geologic map provides new insights to the structure and stratigraphy of the area. The Lower Ordovician Cotter Dolomite is the lowest unit exposed in the area; only the uppermost 20m is exposed in the Jane quadrangle. A disconformity separates the Cotter from the overlying Upper Devonian Chattanooga shale which is approximately 15m thick. A disconformity separates the Chattanooga from the overlying Mississippian complex which forms the caprock for much of the Springfield Plateau. The first succession within the Mississippian is the Kinderhookian shelf sequence consisting of 12 cm of the Bachelor Formation, 2.5-7.5m of the Compton Formation, and 1-3m of the Northview Formation. The upper succession is the Osagean shelf sequence which is gradational and consists of 4-14m of the Pierson Formation, 22m of the Reeds Spring Formation, 50m of the Elsey Formation, and 3-10m of the Burlington-Keokuk limestone. Several faults were mapped in the area including two major faults: the Brush Creek Fault trends east-west across the quadrangle with the up-thrown side to the south displacing approximately 10-15m of strata, and the Pineville Fault trends southwest-northeast in the northwest corner of the quadrangle with the up-thrown side to the southeast displacing approximately 15-20m of strata. Soft sediment deformations, including slump mounds, are present in the Compton with major bed truncations in the Compton and Pierson. These structures reflect tectonism occurring on the passive margin of Southern Laurentia during the early to mid-Mississippian. 28-11 BTH 11 Larson, Mark O. [218649] HIGH RESOLUTION GRAVITY SURVEY TO DETERMINE LOCATION AND EXTENT OF FAULTS IN THE JANE 7.5-MINUTE QUADRANGLE, MISSOURI LARSON, Mark O., Geography, Geology, Planning, Missouri State University, 901 S. National, Springfield, MO 65897, mol@live.missouristate.edu, MICKUS, Kevin, Geology, Missouri State University, Springfield, MO 65897, and EVANS, Kevin, Geography, Geology, and Planning Department, Missouri State University, 901 S. National Ave, Springfield, MO 65804-0089 Detailed geological and geophysical mapping of the Jane 7.5-minute quadrangle in SW MO was undertaken by a group at Missouri State University in 2012. The area is composed of Lower Ordovician and Early Mississippian limestone, dolostone, and shale. Numerous low amplitude structural features and faults were found by surficial geological mapping. In order to further investigate these structural features, a high resolution gravity survey, including a number of profiles at 0.1 mile spacing, was conducted to determine the extent and subsurface nature of the faults in the region. An initial Bouguer gravity anomaly map shows a a general low anomaly in the northern portion of the map, and higher gravity in the southern portion which is probably caused thinning of the Paleozoic sediments toward the south. A horizontal derivative map gravity anomaly map amplifies an anomaly that lines up with an extensive surficially mapped fault. Residual gravity anomaly maps constructed using wavelength filtering and horizontal derivatives and 2-D forward models constrained by surface mapping and density measurements will be constructed in order to better understand the geometry and location of identified and unidentified faults. 28-12 BTH 12 Cook, Tamara J. [218449] JAVASCRIPT TRAVEL TIME SIMULATOR COOK, Tamara J., Plant and Earth Science Department, University of Wisconsin - River Falls, 805 Juniper Dr, Somerset, WI 54025, tamara.cook@my.uwrf.edu A seismogram may appear to be a chaotic record of noise, but amidst the noise there are unidentified earthquake onsets (UEOs). These UEOs are the wave phases before they are identified. Currently, to identify these, one would have to use the Jeffreys-Bullen tables to 2013 GSA North-Central Section Meeting 61
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structures, isolated sink-fills, an
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3-10 11:20 AM Phillips, Andrew C. [
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NaCl+KCl+HCl+H 2 O. Sulfide mineral
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