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Geology collegiate section.

* Crews, J. and J. Hogan. Department of Geology and Geophysics, University of Missouri-Rolla. Origin of Elevated Sub-horizontal Surfaces in the Wichita Mountains, Oklahoma. Digital Elevation Models (DEMs) were used to identify and characterize sub-horizontal topographic surfaces that are readily observed in the Wichita Mountains of Oklahoma. The origin of these surfaces is problematic: 1) Are they remnants of an ancient peneplain? 2) Are they the topographic expression of the roofs of sub-horizontal igneous sills? To address this question, the Tertiary erosional surface of the Southern High Plains was modeled from coordinates and elevations extracted from DEMs. Extracted data was used to generate both a linear and a logarithmic mathematical model. These models were used to predict the elevations of the paleo-erosional surface present throughout the Wichita Mountains during Tertiary time. Coordinates from Flat Mountain generated elevations of 1590' from the linear model and 2188' from the logarithmic model. The actual elevation of Flat Mountain is 2168'. Coordinates from Elk Mountain generated elevations of 1679' from the linear model and 2226' from the logarithmic model. The actual elevation of Elk Mountain is 2262'. The agreement between the actual elevations and those generated by the logarithmic model are consistent with the surfaces in the Wichita Mountains representing remnants of the ancient Tertiary erosional surface.

* Euler, G.E., G. Abdel Aal, and E.A. Atekwana. Department of Geology and Geophysics, University of Missouri--Rolla. Influence Of Microbial-Mineral Interactions On The Electrical Properties Of Unconsolidated Sands. Meso-scale column experiments were conducted to investigate the influence of microbial activity on electrical properties of rocks. The experimental setup consisted of sand-filled columns amended with bacteria and nutrients and/or diesel as well as sand-filled control columns. Results show that the highest relative percent changes in electrical conductivity and alkane-degrading microbial populations occur within the hydrocarbon impacted zones with maximum changes occurring in the free phase diesel layer just above the water saturated zone. The control column showed minimal changes in both the electrical conductivity and microbial populations. Measurements of the microbial population are found to be concomitant with the geophysical data. Induced polarization measurements on cores retrieved from the columns show that the real component of the complex conductivity, a measure of mainly the electrolytic conductivity, is greater in magnitude for both the saturated and unsaturated zones of the diesel-contaminated column in comparison to the uncontaminated column. We conclude that this increase is caused by mineralization of the diesel and subsequent weathering of minerals. Furthermore, measurements of the imaginary component of complex conductivity, a measure of the grain-fluid interface conductivity, shows variations in magnitude between saturated and unsaturated zones in the contaminated and uncontaminated columns. We conclude that microbial-mineral interactions cause a change in both the electrolytic and interfacial conduction properties of unconsolidated sediments.

* Hemmann, R.J. and D.J. Wronkiewicz. Department Geology and Geophysics, University of Missouri--Rolla. Alteration Phase Development During The Oxidative Weathering Of Remnant Sulfide Ores. Metal contamination in the Big River system of southeastern Missouri has been associated with the oxidative weathering and breakdown of remnant sulfide ores from tailings piles and tailings particles that were transported into the river by fluvial processes. The tailings materials contain remnant ore grains of galena, pyrite, sphalerite, and other minerals. Samples of pyrite, galena, and sphalerite were cut and polished to a 600-grit finish and then reacted in stainless steel bombs at 200[degrees]C for time periods of 7 and 35 days. These tests were conducted to gain an understanding of the corrosion processes affecting the sulfides and potential release mechanisms affecting [Pb.sup.2+], [Zn.sup.2+], [Cd.sup.2+], [As.sup.5+], and S[O.sub.4.sup.2-]. Reacted samples were examined with an optical microscope and scanning electron microscope equipped with energy dispersive spectroscopy. Dissolution pits on sulfides and secondary alteration phases were visible on all samples. Alteration phases included various Pb-, Fe-, Zn-oxide and/or sulfate minerals, with phases on sphalerite also containing small amounts of arsenic.

* Johnson, R., and Wronkiewicz, D.J. Department of Geology and Geophysics, University of Missouri--Rolla. Concentration And Transportation Analysis Of Heavy Metals In Sediment Core: Ber Juan, Park, Rolla, Mo. The concentration of lead and other metals in urban lake sediments were determined to elucidate fate and transport mechanisms affecting metal distribution patterns. X-Ray diffraction analysis of clay samples showed a mixed assemblage of kaolinite, smectite, and illite clays, as well as a large quantity of quartz. Inductively Coupled Plasma--Mass Spectroscopy (ICP-MS) performed on sediment samples ranging in depths from 0 to 20 centimeters show lead concentrations that correlate with anthropogenic lead usage. Lead concentrations ranged from a minimum of 39.26 ppm to a maximum of 57.48 ppm. Distributions correlate with automotive usage of lead, transport to the lakes may however include lead particles released by air, and/or those deposited in the soil, and subsequently washed into the basin by meteoric water. When compared to other studies of nearby lakes, lower concentrations of lead in these Ber Juan's sediments are evident. These differences may exist due to travel distance of lead particles; more to traffic congestion in other areas, as well as local point sources (i.e. spills at gasoline stations).

* Lasco, D. and J. Hogan, Department of Geology and Geophysics, University of Missouri-Rolla. Crystallization History of the Mount Sheridan Gabbro, Oklahoma. The Mt. Sheridan Gabbro displays evidence for multiple impulses of magma into the chamber resulting in mineralogical layering within the gabbro. Twenty-eight samples were collected up "little" Mt. Sheridan, encompassing 714 vertical feet. The chamber can be subdivided into a large, layered, lower zone, and a homogenous upper zone. The lower zone coarsens upward, displays repetitions in the modal abundance of plagioclase, and the disappearance and reappearance of olivine. Plagioclase in the lower chamber grades from unaltered to heavily altered and displays zonation that changes from poorly developed, patchy zones to sharp, oscillatory zones. Reversely zoned plagioclase phenocrysts and modal variations in key minerals (i.e. olivine) are indicative of influx of fresh magma into the chamber during crystallization. These changes are repeated at least three times in the lower chamber. The upper chamber is a homogenous gabbro that increases in the modal abundance of plagioclase towards the top of the chamber. Field, petrographic, and chemical evidence suggest rock types present in the Mount Sheridan Gabbro formed from fractional crystallization of multiple batches of magma rather than crystallization of a single batch of magma.

Powers, Elizabeth A., Holbrook, John M. Department of Geosciences and Physics, Southeast Missouri State University. Investigation Into Lewis And Clark The Braided/Anastomozing Missouri River From Miami Station To Carrllton. The first mapping of the Missouri River was in 1804 by Lewis and Clark. Since then the river has changed to a single-channel meandering system, assumedly because of human modification. The first alluvial map is underway--by students and faculty at Southeast Missouri State University. They have found that island braided pattern is no older than 3,000 years, making it late Holocene in age. Furthermore, the island braded system was preceded by generations of single-channel meandering rivers within the late Holocene. The question addressed here is why the river had changed its pattern to an island braided system in the late Pleistocene. Braided patterns are usually seen in high slope areas, due to the necessity to have as much surface area of the flow on the bed as possible. However, the slope has not substantially changed over the period in question. One possible alternative is that the river altered to island braided during the Little Ice Age, which lasted from 1400's to 1850. Glacial outbursts may produce similar island-braided patterns. Through literature searches of all modern braided, anastomozing rivers we have come to a potential explanation as to why the river could have shown this island braided morphology. We propose that ice damming the flow of the river during Little Ice Age spring thaw periodically blocked the channel simulating outburst conditions. This created many single channels in and an overall anastomozing river system, with bars.

David J. Wronkiewicz

University of Missouri--Rolla
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Title Annotation:Collegiate & Senior Divisions
Author:Wronkiewicz, David J.
Publication:Transactions of the Missouri Academy of Science
Geographic Code:1U4MO
Date:Jan 1, 2004
Words:1336
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