SGE Student Research
Poster Session at the 2016 GSA Meeting
Denver, Colorado
2016 Austin A. Sartin Best Poster Award
The recipients of the 2016 Austin A. Sartin Best Poster Award are Alexa Harrison and Nicholas
Schrecongost. Both are students at Radford University in Radford, VA where Epsilon Eta
Chapter is located. Their winning research poster was ERUPTIVE SEQUENCE AND
PROCESSES IN A NEOPROTEROZOIC INTRACONTINENTAL RIFT: THE MOUNT
ROGERS FORMATION, SW VA. (Pictured are Alexa Harrison and SGE President Aaron
Johnson.)
2016 National Council Best Poster Award
Sigma Gamma Epsilon President Aaron Johnson presents Jessica Robinson with the 2016
National Council Best Poster Award. Not pictured is Allison Jones. Both are students at
University of Pacific, CA where Eta Upsilon Chapter is located. Their winning poster was titled
PRELIMINARY OUTCROP-SCALE RF/PHI PETROFABRIC ANALYSIS OF
CONGLOMERATE FROM THE JURASSIC TUTTLE LAKE FORMATION; MOUNT
TALLAC ROOF PENDANT, EL DORADO COUNTY, CA.
2016 Sigma Gamma Epsilon Undergraduate Research (Posters)
List of 2016 Abstracts
Abstract id# 285025, Requested: Poster
EVIDENCE OF THE FIRST MARINE INCURSION IN THE SANTA ROSALIA BASIN,
THROUGH THE DISTRIBUTION OF THE BASAL LIMESTONE IN THE UPPER
MIOCENE BOLEO FORMATION
GUERRA, Daniel, Department of Geological Sciences, San Diego State University, 5500
Campanile Dr., San Diego, CA 92182, PEREZ, Ana, Departamento De Ingenieria en Minas,
Metalurgia y Geologia, Universidad de Guanajuato, Hacienda San Matias, Guanajuato, 37320,
Mexico, BROWN, Eric R., Department of Geosciences, University of Missouri Kansas City,
5100 Rockhill Rd., Kansas City, MO 64110, NIEMI, Tina M., Department of Geosciences,
University of Missouri - Kansas City, 5100 Rockhill Road, Flarsheim Hall 420, Kansas City,
MO 64110, MIRANDA, Raul, Departamento de Ingenieria en Minas, Metalurgia y Geologia,
Universidad de Guanajuato, Hacienda San Matias, Guanajuato, 37320, Mexico and
MUROWCHICK, James B., Geosciences, University of Missouri - Kansas City, 5100 Rockhill
Road, Room 420 Flarsheim Hall, Kansas City, MO 64110, [email protected]
The Boleo Fm of Late Miocene age is a sedimentary deposit related to the opening of the Gulf of
California consisting of basal units of conglomerate, limestone, gypsum, and fossiliferous
sandstone overlain by clastic sequences hosting copper ore in the eastern-central part of the Baja
California Peninsula. We collected samples for petrographic and mineralogical analyses of the
Boleo Basal limestone from six stratigraphic sections in the area of Santa Agueda and El Morro
to determine the environment of deposition. Seven units were defined, including: 1)
conglomerate and breccia, 2) massive beds, 3) spongy-like texture with Mn vesicles, 4)
thrombolitic (cottony texture) and stromatolite units, 5) tufa, 6) marine fossiliferous limestone,
and 7) limestone with structures resembling gas-escape pipes. We mapped the distribution of this
Basal Limestone facies to reconstruct the paleoenvironmental setting. On the topographic highs
of the deposit, hydrothermal activity produced deposition of a massive to spongy like textures
unit with Mn. The breccia unit may represent the location of hydrothermal vents. The limestone
with vertical gas-escape structures and chalcedony are associated with these rocks. Laterally, in
the topographic lows of the deposit, we find the thrombolites and stromatolites associated with
shallow marine environment. Fossil gastropods, bivalves, and microfossils with lenticular
distribution suggest a tidal channel system deposition in brackish to marine conditions. The
marine fossiliferous limestone provides evidence of marine transgression into the basin.
According to field relationships, the marine sequence was deposited horizontally into an area
where hydrothermal springs produced limestones with some original dip and were subsequently
deformed along local faults. This research shows the difference in the deposition of the studied
outcrops within the limestone, where the tufa and massive to spongy like texture corresponds to a
brackish-fresh water hydrothermal environment in a subtidal channel system. Furthermore, the
unit with thrombolites, stromatolites and marine fossiliferous limestone suggest a seawater
incursion into the basin related to the early rifting of the Gulf of California. This study is part of
the NSF-funded Baja Basins REU project.
Abstract id# 285426, Requested: Poster
MIOCENE VOLCANISM IN THE SANTA ROSALIA REGION, GULF OF CALIFORNIA,
BAJA CALIFORNIA: NATURE OF THE ARC-TO-RIFT TRANSITION AND POSSIBLE
ROLE OF RIFT-TRIGGERED ADAKITE MAGMATISM IN GENERATING BOLEO
STRATIFORM CU-CO-ZN SULFIDES
GUTIERREZ, Evelyn P.1, BOWMAN, Emilie2, MEDYSNKI, Sarah3, BUSBY, Cathy J.3,
LÓPEZ MARTÍNEZ, Margarita4, NIEMI, Tina M.5 and SALGADO MUÑOZ, Valente O.5,
(1)Department of Geological Sciences, California State University, Fullerton, 800 N State
College Blvd., Fullerton, CA 92831, (2)Jackson School of Geosciences, University of Texas at
Austin, 23rd, Austin, TX 78759, (3)Department of Earth and Planetary Sciences, University of
California, Davis, One Shields Ave., Davis, CA 95616, (4)Depto. Geología, Centro de
Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California Norte,
Mexico, (5)Department of Geosciences, University of Missouri - Kansas City, 5100 Rockhill
Road, Flarsheim Hall 420, Kansas City, MO 64110, [email protected]
Miocene volcanic rocks in the Santa Rosalía region record the transition from arc magmatism,
due to subduction of the Farallon plate, to rift magmatism, related to the opening of the Gulf of
California (Conly et al., 2005)1; these are estimated to be ~24-12 Ma and ~12 Ma to present
(respectively), using published plate tectonic models. As part of the Baja Basins NSF-REU
(Research Experience for Undergraduates) project, we describe detailed geologic maps of
volcanic rock outcrops that surround and underlie the Santa Rosalía rift basin sedimentary rocks,
the type locality of Boleo stratiform Cu-Co-Zn sulfides, currently being mined by Minera Boleo.
We present new petrographic, geochemical and 40Ar/39Ar geochronological data on the volcanic
rocks (REU 2016), integrated with data gathered by the 2015 REU cohort.
We have now mapped 27 distinct volcanic map units, described the petrography of 58 samples in
thin section, obtained and interpreted major and trace element geochemical data on 42 samples,
and determined 40Ar/39Ar ages on 9 samples (3 more in progress). Lithofacies and compositions
include: basalt to andesite lava; trachyandesite lava and lava dome; andesite peperite intrusion;
silicic ignimbrite; andesite and dacite block-and-ash-flow tuff; and adakite lava and hypabyssal
intrusion. We recognize a gradual transition from arc to rift signatures, spanning 13 Ma to 9.4
Ma, based on geochemistry integrated with 8 of our new 40Ar/39Ar dates. However, we have also
discovered a younger magmatic event, consisting of adakite lava and hypabyssal intrusion, with
an age of 6.11 ± 0.27 Ma (40Ar/39Ar plateau ages, hbl and groundmass). We follow Conly (et al.,
2005)1 in interpreting the adakites as the product of rift-related melting of a mantle previously
metasomatized by subduction.
Our new age on the adakites is the same as the age of the Boleo stratiform Cu-Co-Zn sulfides,
which Holt et al. (2000)2 reported at 6.93–7.09 Ma (for the base of the Boleo Formation) to
6.14–6.27 Ma (for the top). We thus show that local adakite magmatism provided a heat engine,
and possibly the hydrous fluids, for mineralization in the sedimentary basin.
Abstract id# 286103, Requested: Poster
ANALYSIS OF A FOSSILIFEROUS SANDSTONE SEQUENCE OF THE PLIOCENE
TIRABUZON FORMATION AT SANTA AGUEDA, SANTA ROSALIA BASIN, BAJA
CALIFORNIA SUR, MEXICO
GAULD, Sarah, Geoscience, University of Missouri - Kansas City, 5100 Rockhill Road,
Kansas City, MO 64110, GATES, Jesse Kikuchi, Geoscience, Humboldt State University, 1
Harpst St, Arcata, CA 95521 and NIEMI, Tina M., Department of Geosciences, University of
Missouri - Kansas City, 5100 Rockhill Road, Flarsheim Hall 420, Kansas City, MO 64110,
[email protected]
The Santa Rosalia Basin located along the western shore of the Gulf of California in central Baja
California Sur, México is filled by a sequence of Miocene to Quaternary sediment deposited
during the initial rifting of the gulf and subsequent incursion of marine waters. Wilson (1955)
divided the basin sequence into the Boleo, Gloria, Infierno, and Santa Rosalia formations, each
separated by a local angular unconformity, and capped by marine and fluvial terraces. We
measured a 34-m-thick section of the Tirabuzon Formation (formerly known as Gloria Fm),
along Estero Santa Agueda where the formation dips gently eastward and has an erosional
contact with volcanic and lower Boleo Fm rocks that dip 55° east. We divided the section into 16
beds and collected samples for petrographic, mineralogical, and fossil analyses. The basal 0.3-mthick sandy conglomerate with sub-rounded volcanic and Boleo Fm cobbles, a localized fossil
organic debris, and shell fragments represents a transgressive lag. The lower five beds are mostly
bioturbated, fine-grained sandstone with abundant disarticulated fossil pectins, oysters, forams
and ostracods indicating marine subtidal conditions. A cross-bedded, bioturbated sand (Bed 6)
with possible root casts suggest a backshore environment. Beds 7- 13 are an interbedded
sequence of grey to brown, fine sandy silt with few fossils. A green, glauconite-rich sandstone
(Bed 14) with abundant shells and whole sand dollars, a tan sandstone (Bed 15) with few shells,
and uppermost 3-m-thick conglomerate (Bed 16) with abundant shells (coquina) are interpreted
as the transition from the marine to beach facies. Petrographic analyses shows that the
sandstones are predominantly calcite-cemented, felspathic litharenites or lithic feldspathic
arenite, with angular grains and accessory minerals of isolated crystals of amphibole, biotite,
plagioclase, and pyroxene. A pulse of tectonic tilting and erosion of most of the Boleo formation
occurred prior to deposition of this section of the Tirabuzon Fm. The sea transgressed and
rapidly brought marine shelf-depth waters into the basin and then regressed twice in the section.
The section is capped by Quaternary marine terrace indicating the basin continued to subside and
was uplifted during a second phase of tectonics. This research is part of the Baja Basins REU.
Abstract id# 286575, Requested: Poster
STRATIGRAPHY AND MINERALOGY OF THE MIOCENE BOLEO FORMATION
GYPSUM IN THE SANTA ROSALIA BASIN OF BAJA CALIFORNIA SUR, MEXICO
MAHER, Anna-Turi1, JAIME-GERALDO, Aldo Javier1, NIEMI, Tina M.2 and
MUROWCHICK, James B.3, (1)Geology, University of Nebraska Omaha, Omaha, NE 68114,
(2)Department of Geosciences, University of Missouri - Kansas City, 5100 Rockhill Road,
Flarsheim Hall 420, Kansas City, MO 64110, (3)Geosciences, University of Missouri - Kansas
City, 5100 Rockhill Road, Room 420 Flarsheim Hall, Kansas City, MO 64110,
[email protected]
Gypsum outcrops within the Santa Rosalia rift basin of east central Baja California Sur were
defined by Wilson (1955) as the basal deposits of the Boleo Formation, predating the Cu-Zn-MnCo mineralization. We studied the late Miocene Boleo Fm gypsum and interbedded clastic units
exposed as broad folds along Arroyo del Boleo to determine the temporal relationship of these
rocks to the ore mineralization.
We measured a 110.5 m-thick stratigraphic section and divided it into five gypsum/anhydrite
sections separated by four clastic layers. The basal gypsum/anhydrite unit (34.5 m thick) is
massive or flat/wavy laminated sections with thinly bedded gypsum/anhydrite. This is cut by
channelized and graded clastic beds (14 m thick). The second section of gypsum (11.5 m thick)
contains black massive gypsum/anhydrite and wavy to flat laminated gypsum/anhydrite.
Seismites are present within the laminated sequence attesting to active syndepositional
tectonism. Copper staining is evident on the face of this outcrop. A second clastic unit (3.5-0.5 m
thick) contains graded fluvial beds, a debris flow, and a clastic dike. The third (33 m thick)
gypsum/anhydrite section contains massive to laminated or thinly bedded gypsum/anhydrite with
some intercalated thin siltstone beds. The third clastic unit (1 m thick) is a sequence of
interbedded laminated to thin beds of sandstone and mudstone. Above is (8.5 m thick) massive to
laminated or thinly bedded gypsum/anhydrite interbedded with mud/siltstone. The fourth clastic
layer (1 m thick) contains graded thin beds of mudstone and silty sandstone marked at its base by
a notable angular unconformity. The uppermost unit (6.5 m thick) has poorly laminated
gypsum/anhydrite interbedded with silt and massive to poorly laminated gypsum/anhydrite.
The trace mineralogy of the evaporites include strontianite, tenorite and Fe, Mn and Cu-Co
oxides, and fine-grained sulfide grains, including a Cu-Fe sulfide, villamaninite
((Cu,Fe,Co,Zn)S2), and an unidentified Co-S phase with minor Cu and Fe. The sulfides occur
along bedding planes, suggesting an influx of metal-bearing fluids into the evaporitic
environment with periodically reduced conditions. Such mineralization suggests that the gypsum
deposition is coeval with ore formation. This study is part of the NSF-funded Baja Basins REU.
Abstract id# 287820, Requested: Poster
ROVER INSTRUMENTATION: IDENTIFYING EXTRATERRESTRIAL BIOSIGNATURES
SCHAUFLER, Ruby L, Gustavus Geology Department, Gustavus Adolphus College, 800 west
college ave, St.Peter, MN 56082, BARTLEY, Julie K., Geology Department, Gustavus
Adolphus College, 800 W. College Ave, St. Peter, MN 56082 and YINGST, R. Aileen, Planetary
Science Institute, 1700 E. Fort Lowell Rd., Suite 106, Tucson, AZ 85719,
[email protected]
Of the telluric planets in our solar system, Mars is the most likely to preserve evidence of life.
Although Mars has a thin atmosphere today, its early history may have been habitable. The three
rovers sent to Mars share a common mission, to explore whether or not Mars has or ever had a
habitable surface environment. To date, these rover missions have identified several ancient
environments that were potentially habitable, including: fluvial, lacustrine, and subsurface water
systems.
Like their terrestrial counterparts, habitable environments on Mars have a range of potential for
biosignature preservation. At a scale detectable by rovers, water-influenced sediments may
preserve evidence of biological activity, including microbially-induced sedimentary structures
(MISS) in clastic rocks and microbialites in chemical sedimentary rocks. Identifying these
mesoscale structures and confirming whether they are microbially influenced is a challenge due
to the size and subtle nature of their features.
Differentiating abiotic sedimentary structures from MISS and microbialites is a challenge even
for geologists on Earth. It is even more difficult to distinguish these features for operators of a
rover millions of km away. Choosing instruments that are capable of capturing the scale and
detail of these features is crucial to finding biosignatures on Mars. If the wrong resolution is
used, or the feature observed is too far away to capture the detail, the biosignatures will be
overlooked and the mission will be unsuccessful.
Research with the Geo-Heuristic Operational Strategies Test (GHOST) team has tested various
methods of traverse and collection strategy. These field tests compared efficiency and
effectiveness of differing methods to locate, identify, and collect biosignatures. The field work
conducted in the spring of 2016 demonstrated that mesoscale (0.1-10 mm) data is crucial when
identifying MISS and microbialites. Without clear resolution on the sub-mm to cm scale, key
features that allow confident assessment of biogenicity are unrecognizable. Further research is
being conducted on the type of instrumentation necessary for identifying mesoscale
biosignatures, specifically what resolution will be needed for distinguishing MISS and
microbialites from abiogenic structures at outcrop scale.
Abstract id# 287915, Requested: Poster
ERUPTIVE SEQUENCE AND PROCESSES IN A NEOPROTEROZOIC
INTRACONTINENTAL RIFT: THE MOUNT ROGERS FORMATION, SW VA
HARRISON, Alexa1, SCHRECONGOST, Nicholas1 and MCCLELLAN, Elizabeth2, (1)Dept.
of Geology, Radford University, P.O. Box 6939, Radford, VA 24142, (2)Geology, Radford
University, P.O. Box 6939, 101 Reed Hall, Radford, VA 24142, [email protected]
Convergence of supercontinents, and their subsequent rifting and breakup, is a major theme in
the theory of plate tectonics. Two end-member models for rifted margins have been proposed:
the active rift model, in which a rising plume of magma causes tension and rifting in the
overlying crust, vs. the passive model in which stretching in the crust is caused by far-field
stresses related to plate movements. In ancient rifts, the relative timing, sequence, and style of
volcanic eruptions can help discriminate between these models. The supercontinent of Rodinia
was assembled between 1.3-1.0 Ga. The eastern Laurentian margin of Rodinia began to extend at
ca. 760-780 Ma, but did not completely break up until ca. 550 Ma, with the opening of the
Iapetus ocean. In SW Virginia, the Neoproterozoic Mount Rogers Formation (MRF) records the
eruption of bimodal volcanics during early stages of rifting, ~760-750 Ma. Geochemical analyses
of basalts and rhyolites from the MRF show a plume ‘geochemical signature’ for the magmas,
suggesting that the active rift model may be applicable. It is important to determine if the
eruptive sequence and field relationships are consistent with this model.
Along with clastic sedimentary rocks and basalt, the MRF includes several rhyolite members: the
Fees, Buzzard Rock, Whitetop, and Wilburn Rhyolites (Rankin, 1993). Each of these is
distinguished by its phenocryst assemblage and distinctive textures that indicate emplacement by
either lava flows or pyroclastic processes. Previous mapping by our research group has
recognized an additional rhyolite body, informally named the Bearpen rhyolite. Based on field
mapping, the Bearpen locally appears to occur stratigraphically between the Fees Rhyolite in the
lower MRF and the Whitetop Rhyolite in the upper MRF, and is distinguished by clusters of
reddish alkali feldspar phenocrysts, flow banding, and presence of fiamme. However, its U-Pb
zircon age date of 756 Ma +/- 3.1 Ma overlaps with ages of the other rhyolite members (as
reported by Tollo et al., 2012), except for the younger Wilburn Rhyolite. This study describes the
petrographic and microscopic characteristics of the Bearpen, in order to understand its formation
processes and place in the eruptive sequence.
Abstract id# 277182, Requested: Poster
CLAY MINERAL CONCENTRATION WITH DEPTH AND LAND USE HISTORY IN THE
CRITICAL ZONE IN CALHOUN, SOUTH CAROLINA
MORAES, Anthony, SCHROEDER, Paul A. and AUSTIN, Jason, Department of Geology,
University of Georgia, 210 Field St., Athens, GA 30602-2501, [email protected]
History of Land Use at the Critical Zone Observatory (CZO) in Calhoun, South Carolina has
been well documented and studied. Land use, climate, biotic factors and topography all
contribute to rates of chemical denudation (mass loss) and chemical weathering (mineral
transformations). This comparative study contrasts clay mineral assemblages in a hardwood plot,
which has not had recent anthropogenic influence, and an adjacent reforested pine plot that has
been historically farmed. Methods used to characterize the soil cores taken from the respective
plots include X-ray diffraction of oriented clay fraction with treatments of K-, Mg-, and Nasaturation in the air-dried, ethylene glycol (EG), and heated (100O, 330O, and 550OC) states.
Based on weathering intensities, early end member minerals with little weathering are biotite and
muscovite, while the other end member is thoroughly weathered kaolinite soils. Bedrock at the
Calhoun Experimental Forest is Neoproterozoic gneiss, which shows a progression of micas,
interlayered vermiculite, vermiculite, smectite, interlayered kaolin-smectite, and kaolin with
increasing depth. In shallow depths of older profiles, kaolin-smectite interlayering should be
apparent due to the long time for weathering and erosion. Smectite should be seen at greater
depths of younger profiles using the same reasoning. From 240 XRD patterns of varying depths
and methods, smectite interlayering begins at 40 centimeters at the hardwood site and at 100
centimeters at the pine site. This data is consistent with the predictions of where smectite
interlayering should be found.
Abstract id# 279681, Requested: Poster
PALEOSOLS FROM ELEUTHERA, THE BAHAMAS: GEOCHEMISTRY AND
MINERALOGY
GAUVEY, Kaitlyn L., Geography and Geology, Sam Houston State University, 1905
University Avenue, Huntsville, TX 77340 and SUMRALL, Jonathan B., Geography and
Geology, Sam Houston State University, PO Box 2148, Huntsville, TX 77341, [email protected]
Field reconnaissance of paleosols on Eleuthera, The Bahamas occurred during winter 2015 field
season. During this work, 50 samples were collected and consisted of terra rossa paleosols,
micritic crusts, and cave minerals developed on terra rossa paleosols in flank margin caves.
Major element (Calcium, Magnesium, Aluminum, Silicon, and Iron) and trace element
(Potassium, Sodium, and Strontium) analyses using ICP-AES and mineralogic determinations
using x-ray diffraction (XRD) were conducted Two terra rossa paleosols were selected to
analyze insoluble residue by size fraction.
Elemental analysis differentiated paleosol type and corresponds well to macroscopic field
interpretations. Geochemical relationships exist between the abundance of Fe, Al, and Si in
paleosol samples, allowing for determination of palesol type. Elemental differences between
paleosols and micritic crusts are further demonstrated by examining the abundance of Mg, Al,
and Fe. Paleosol samples had higher relative abundances of Al and Fe while micritic crusts had
higher relative abundance of Mg.
To isolate insoluble residue, samples were treated with pH 5 NaAoC solution, hydrogen
peroxide, and centrifuged for size fractionation. Silt and coarse clay fractions were analyzed
using x-ray diffraction. Chemical and heat treatments were performed on coarse clay fractions.
These fractions were K-treated and heated to 350 and Mg-glycol treated. Dominant mineralogy
of coarse clay is Fe-rich Chlorite, Illite, and possibly Boehmite.
While sampling paleosols in Hatchett Bay Cave, earthen nodules were identified on the outcrop
of paleosol. Three cave mineral samples were collected from a guano-coated exposed paleosol
within Hatchett Bay Cave. The mineral samples were rusty brick-red with earthen nodules.
These samples were powdered and analyzed using x-ray diffraction. Woodhouseite
(CaAl3(PO4)(SO4)(OH))6, was the dominate mineral identified within these three samples. This
complex phosphate mineral forms by the degradation and leaching of guano into underlying
paleosols. This is the first documented occurrence of Woodhouseite in the Bahamas, which is a
function of the infrequency of exposed paleosols in a phosphate-rich environment (guano
deposits in a cave).
Abstract id# 279831, Requested: Poster
INVESTIGATING THE CORRELATION BETWEEN WATERSHED SURFACE GEOLOGY
AND DETRITAL ZIRCON AGE PATTERNS IN MODERN RIVERS
GOSNEY, Lucas C., Department of Earth and Environmental Sciences, University of Iowa, 115
Trowbridge Hall, Iowa City, IA 52242, FINZEL, Emily S., Earth & Environmental Science
Department, University of Iowa, Trowbridge Hall, North Capitol Street, Iowa City, IA 52242
and ENKELMANN, Eva, Department of Geology, University of Cincinnati, Cincinnati, OH
45221, [email protected]
The purpose of this research is to discover whether there is a correlation between the surface area
of exposed igneous rocks within a particular watershed and the distribution of age ranges
measured using U-Pb dating of detrital zircons from modern river sediments taken from the
watershed. In order to investigate this problem, we collected samples from five rivers that drain
the Talkeetna and Chugach Mountains in southcentral Alaska. The most recent geologic map of
Alaska (Wilson et al., 2015) was cropped for each watershed in ArcMap. These data were used
to calculate the area of igneous, sedimentary, and metamorphic bedrock suites within each
watershed. Where geochronologic age data are available for the igneous bedrock suites, that
group was subdivided by age. For each detrital zircon sample, the U-Pb ages were classified
using the same age categories as the igneous bedrock suites from the parent watershed.
Preliminary comparisons between the percentage of area for each igneous bedrock age
distribution within an individual watershed calculated from the geologic map to the percentage
of each age distribution from the U-Pb data from our detrital zircon samples seem to indicate that
there is a weak correlation between the two datasets. Potential explanations for this mismatch
may be that 1) the watersheds have a large proportion of sedimentary and metamorphic bedrock
relative to igneous bedrock such that a large number of zircons are being derived from the
sedimentary and metamorphic units in each watershed, 2) there are both felsic and mafic igneous
rocks in the watersheds, and because felsic units typically contain a greater relative abundance of
zircons than mafic units, our U-Pb data could be biased toward the zircons derived from the
felsic igneous units, or 3) there is only sparse geochronologic data from within our study area so
our data could be exhibiting a large proportion of ages from undated or poorly dated units.
Abstract id# 280220, Requested: Poster
A NEW CAVE SURVEY TECHNIQUE FOR IMPROVING 3D RENDERING AND
VOLUMETRIC ACCURACY WITHIN THE COMPASS SOFTWARE
BURTON, M. Isaac1, CARPENTER, Dylan D.1 and LARSON, Erik B.2, (1)Natural Sciences,
Shawnee State University, 940 Second St, Portsmouth, OH 45662, (2)Physics and Earth Science,
Moravian College, 1200 Main St, Bethlehem, PA 18018, [email protected]
Cave mapping is an integral part of karst research. Current cave survey methods used in karst
science are well suited to the task of making plan view illustrative maps of a given cave, they are
however of limited use when attempting to make estimates of a cave volume and 3-D
representations. This is due to prevailing survey methods that focus on maximizing total survey
coverage, relying heavily on a surveyor’s personal ability to estimate cave dimensions while
detailing the sketch. Traditionally, survey stations—where the various data points are taken—are
daisy chained throughout a cave system in such a way as to maximize coverage while
minimizing stations. This usually results in stations being placed at changes in passage direction
and identifiable landmarks.
Our method was developed from the beginning with the intent of producing accurate 3D models
in Compass (a freeware computer program), with a focus on improving the accuracy of volume
estimates. While the data taken at each station is the same as traditional methods, the station
placement is fundamentally different. Rather than allowing the passage and line of sight to
determine station placement, stations are placed at a central location in the passage at each
change in passage morphology—be it wall, ceiling, and/or floor. This method was tested not
only on idealized passage shapes, but on three flank margin caves and three littoral caves on
Eleuthera, The Bahamas. The new cave survey methods were then compared directly to
traditional surveys of these same caves performed by other surveyors. The new survey technique
did not greatly increase the number of stations or the total survey time, but it made significant
improvements in the accuracy of the cave renderings and cave volumes.
Beyond that, a second-pass refinement of our data was made by drafting our maps using Adobe
Illustrator and standard plan view mapping techniques, then re-surveying these maps by hand—
adding many more stations, and subsequently many more data points. This resulted in another
increase in cave rendering and volume accuracy, at no cost of additional time in the field. The
combination of these surveying techniques provides a massive increase in 3D modeling and cave
volume accuracy without the need for specialized equipment such as LiDAR or any substantial
additional field work.
Abstract id# 280223, Requested: Poster
CALCULATING DISSOLUTION RATES OF CARBONATE ROCKS: A NEW
LABORATORY METHOD
LEESBURG, Jessica N.1, HALL, Vincent P.1 and LARSON, Erik B.2, (1)Natural Sciences,
Shawnee State University, 940 Second St, Portsmouth, OH 45662, (2)Physics and Earth Science,
Moravian College, 1200 Main St, Bethlehem, PA 18018, [email protected]
The dissolution of carbonate rocks such as limestone and dolostone can be seen in karst
landscapes all around the planet. The dissolution of these rocks can lead to the lowering of a
landscape surface, denudation. The rate at which this denudation occurs naturally is difficult to
measure in the field due to the time scales involved. It is also difficult to determine through
theoretical calculations due to the heterogeneous nature of carbonate rocks. Therefore, it may be
difficult to reconcile field observations and theoretical data. Some attempts have been made in
the laboratory setting to overcome and reconcile these differences, and this abstract discusses a
new variation of those methods.
Samples of calcite, eogenetic limestone from Eleuthera, The Bahamas, and telogenetic dolostone
from Michigan’s Upper Peninsula were analyzed. Samples were individually tested by being
submerged in a deionized water solution that was continuously saturated with CO2 while
conductivity and pH levels were recorded at regular intervals to ensure CO2 saturation. Each
sample was prepared for the experiment by being cut into an approximate 1.5cm x 1.5cm x
1.5cm cube and covered in electron-negative epoxy and cyanoacrylate glue. One side was left
exposed and was subsequently polished. A stationary cage made of styrene held the sample and
was placed in a 1000ml beaker so that the sample was suspended in the center and the exposed
side faced the bottom where a magnetic stir bar continuously agitated the solution. The entire
setup was covered in Parafilm to prohibit evaporation.
Each sample went through three trials for a period of 3-5 days and between each trial the
exposed side was repolished to ensure consistency. Preliminary results indicate that the design of
the experiment was effective when comparing the conductivity curves between trials and
samples. Conductivity acted as a proxy for Ca2+ and Mg2+ ions that were liberated through the
dissolution. As expected the calcite had the fastest relative rate of dissolution, followed by the
eogenetic limestone and the telogenetic dolostone. Future work entails collecting water samples
during the experiment and utilizing them to calibrate the conductivity values to Ca2+ and Mg2+
concentrations in order to calculate the true dissolution rate.
Abstract id# 280226, Requested: Poster
GRIKE (KLUFTKARREN) DEVELOPMENT IN THE HIAWATHA NATIONAL FOREST,
UPPER PENINSULA, MICHIGAN
BURTON, M. Isaac, Natural Sciences, Shawnee State University, 940 Second St, Portsmouth,
OH 45662, SUMRALL, Jonathan B., Geography and Geology, Sam Houston State University,
PO Box 2148, Huntsville, TX 77341 and LARSON, Erik B., Physics and Earth Science,
Moravian College, 1200 Main St, Bethlehem, PA 18018, [email protected]
The St. Ignace District of the Hiawatha National Forest is host to extensive grike fields, the
formational history and timing of which has been little researched and is, as such, not well
understood. These grikes are present throughout the region where the Engadine Group, a middle
Silurian dolostone composed of the Rockview, Rapson Creek, and Bush Bay Formations,
outcrops. Grikes (Kluftkarren) are linear dissolutionally enlarged joints, usually forming within
exposed carbonate bedrock. The mechanisms and timing of the formation of the grike fields and
other local karst features (primarily relict littoral caves and boulder fields) are all bound tightly
by the Upper Peninsulas glacial history, and as such, understanding these grike fields will play a
major role in understanding the area as a whole.
Grike morphology and orientation data was collected during both the summer of 2015 and the
summer of 2016. This data included width, depth, length, and azimuth measurements. This data
was used to calculate the apparent dissolution rate of the grikes, assuming a 0 mm starting width
and that development began after glacial retreat and emergence from glacial lakes Algonquin and
Nipissing at 11ka and 4ka, respectively. The results, when compared with the theoretical
dissolution rates for the given lithology and climate, showed a large disconnect between the two
values. Observed dissolution rates were calculated to be between 3 and 25 mm / 1000 years,
whereas theoretical rates were determined to be just 0.0177 mm / 1000 years. Grikes that were
contained within the Rockview Formation appear to have a slower dissolution rate (3-12 mm /
1000 years) than the grikes contained within the Bush Bay Formation (12-25 mm / 1000 years).
Several factors have been determined as possible explanations for these discrepancies; 1) carbon
loading from organic debris increasing aggressiveness, 2) freshwater-freshwater mixing zones
affecting dissolution efficiency, 3) non-zero initial grike widths due to the effects of glacial
loading/unloading on regional joint sets or grike development before/during glaciation, and 4)
lithological heterogeneity modifying dissolution rates.
Abstract id# 280661, Requested: Poster
PRELIMINARY OUTCROP-SCALE RF/PHI PETROFABRIC ANALYSIS OF
CONGLOMERATE FROM THE JURASSIC TUTTLE LAKE FORMATION; MOUNT
TALLAC ROOF PENDANT, EL DORADO COUNTY, CA
ROBINSON, Jessica M.1, JONES, Allison D.1, BURMEISTER, Kurtis C.2, SEVERSON,
Allison R.3, NOETHE, Samuel A.4 and STEWART, Michael A.5, (1)Department of Geological
& Environmental Sciences, University of the Pacific, 3601 Pacific Ave, Stockton, CA 95211,
(2)Department of Geological & Environmental Sciences, University of the Pacific, 3601 Pacific
Avenue, Stockton, CA 95211, (3)Department of Geology and Geological Engineering, Colorado
School of Mines, 1500 Illinois St, Golden, CO 80401, (4)Department of Geology, University of
Illinois, 605 E Springfield Ave, Urbana, IL 61801, (5)Department of Geology, University of
Illinois, 605 E Springfield Avenue, Champaign, IL 61820, [email protected]
A preliminary 3D Rf/phi analysis of outcrop-scale petrofabrics in near-orthogonal exposures of
conglomerate reveals a heterogeneous pattern of penetrative strain within the southernmost Mt
Tallac roof pendant. Our analysis was conducted in outcrops of the Jurassic Tuttle Lake
Formation near Grass Lake in the Desolation Wilderness Area of Eldorado National Forest. The
Tuttle Lake Fm contains a thick sequence of weakly metamorphosed volcaniclastic deposits cut
by four sets of intermediate dikes, the Jurassic Keith’s Dome granodiorite pluton, and an array of
predominantly sinistral ductile shear zones and brittle faults. Observations of shapes and
orientations of clasts in the Tuttle Lake Fm led to the hypothesis was the unit was deformed by
the intrusion of the Keith’s Dome pluton. To test this hypothesis, we examined petrofabrics at
nine locations along a N-S transect between Grass Lake and the Keith’s Dome pluton. Four nearorthogonal faces containing clasts with discernable boundaries were selected at each location.
Outlines of at least 60 clast boundaries (color coded by clast composition) were traced onto clear
plastic overlays. Photo-registration marks, location information, and the strike and dip of each
face were also recorded onto overlays. Photographs of overlays were adjusted, rectified, and
reoriented in Adobe Photoshop. The EllispeFit computer program (Vollmer, 2015) was used to
conduct Rf/phi analysis of the clasts in each tracing and to compile fabric ellipsoids at each
location. Our results reveal a range of fabric magnitudes and shapes (weakly oblate to
moderately prolate, E 0.15 to 0.81, Nu -0.31 to 0.47). When bedding is restored to horizontal,
oblate fabrics appear to be consistent with vertical flattening associated with deposition and
compaction. Prolate fabrics record higher strains and subhorizontal long (X) axes that generally
trend NE-SW. However, these X axes orientations correlate poorly with each other and with
trends of dikes, shear zones, and faults in the Grass Lake area. Given fabrics measured in other
Sierran Jurassic roof pendants, it is interesting that the Tuttle Lake Fm has not accumulated a
more pervasive penetrative strain. Further study is needed to determine the cause of the fabric
heterogeneities and their context in the regional host rock geology.
Abstract id# 282273, Requested: Poster
GAMMA RAY AND MAGNETIC SUSCEPTIBILITY PROFILES AS A TOOL FOR
CORRELATION OF CARBONATE-EVAPORITE STRATA: A CASE STUDY FROM
UPPER ORDOVICIAN RED RIVER FM., NORTH DAKOTA
CERPOVICZ, Alexandria F. and HUSINEC, Antun, Geology Department, St. Lawrence
University, 23 Romoda Drive, Canton, NY 13617, [email protected]
Gamma ray and magnetic susceptibility (MS) profiles were examined from the entirely
subsurface Upper Ordovician Red River Formation, North Dakota. We used data from a well in
eastern North Dakota covering lower part of the formation, and three wells from western North
Dakota representing the upper part of the formation. The carbonate facies analyzed include, from
distal (basin-central) to proximal (basin-marginal): burrowed skeletal mudstone and wackestone
(deeper subtidal), skeletal wackepackstone (moderately shallow subtidal), skeletal packstone and
grainstone (high-energy, open-marine, well-oxygenated shoal), poorly fossiliferous lime
mudstone (restricted subtidal), barren lime mudstone (restricted euhaline to mesosaline lagoon),
thrombolite (shallow mesohaline subtidal), laminated dolomite (shallow mesohaline subtidal to
intertidal), intraclast breccia-conglomerate (supratidal to intertidal). Non-carbonate facies include
deeper-water shale and anhydrite (shallow penesaline subaqueous setting) that is restricted to the
basin center. Generally, the mean MS values increase from the most distal towards the more
proximal facies, suggesting that the MS signal preserved could be related to relative sea-level
oscillations (MS being highest during sea level lows when siliciclastic impurities are delivered to
the basin). Gamma ray values for carbonate facies are very low, and they poorly correlate with
MS values of the facies; the only exception is shale with excellent positive correlation between
the GR and MS values. The relationship between the GR and MS signal versus facies stacking
pattern is analyzed in order to assess the possible significance of GR/MS variations as a proxy
for high-frequency sea-level oscillations recorded in carbonate facies.
Abstract id# 282497, Requested: Poster
PALEOSOLS FROM ELEUTHERA, THE BAHAMAS: PETROGRAPHIC ANALYSIS
SIDES, Kristen, Department of Geography and Geology, Sam Houston State University,
Huntsville, TX 77340 and SUMRALL, Jonathan B., Geography and Geology, Sam Houston
State University, PO Box 2148, Huntsville, TX 77341, [email protected]
Field reconnaissance of paleosols on Eleuthera, The Bahamas occurred during winter 2015 field
season. During this work, 48 samples were collected that consisted of terra rossa paleosols and
micritic crusts. Standard petrographic thin sections were created from each sample; however,
only terra rossa paleosols were examined for this project. Standard petrographic analysis using a
polarizing light microscope coupled with a mechanical stage were conducted to determine
texture and composition of these samples.
Paleosols, lithified soils, are a common topographic feature found on carbonate platforms,
however, the amount of research conducted on paleosols in The Bahamas has been marginal.
Most Eleutheran paleosols appeared to be poorly cemented and highly porous in the field. Thin
section analysis revealed that porosity is much lower than expected from field observations
(never exceeding 9%) and that the paleosols are fairly well cemented (sometimes with as much
as 33% cement).
Based on petrographic texture, two types of paleosols were identified on Eleuthera. Type 1
Paleosols are described as paleosols with greater than or to equal relative percentages of
insoluble material compared to the percentages of allochems. Type 2 Paleosols are described as
paleosols with significantly more allochems than insoluble material. While the texture of these
two paleosol types differ, their formation is the same. As insoluble dust and other material
collects on an exposed platform surface, a soil develops. The platform surface is highly
karstified, so soil thickness varies with the bedrock surface. Type 1 Paleosols are thought to
represent lithified soil material, while Type 2 Paleosols represent infiltration of soil material into
the underlying bedrock and/or a paleokarst breccia surface. Outcrops that have Type 2 Paleosols
exposed represent paleosol deposits that were eroded prior to lithification or have been eroded
since modern exposure. Outcrops with Type 1 Paleosols represent thicker accumulations of relic
soil material either through less erosion or thicker accumulations due to topographic lows in the
paleosol bedrock surface.
Abstract id# 282538, Requested: Poster
EFFECTS OF MAFIC INTRUSION ON TUFFACEOUS HOST ROCK, MEADOW CREEK
BASIN, BLACK MOUNTAINS, AZ: FIELD, GEOCHEMICAL, AND PETROLOGIC
EVIDENCE REGARDING FORMATION OF A GLASSY BORDER FACIES
WILLIAMS, Sarah G., Department of Geosciences, University of Arkansas, Fayetteville, AR
72701, SMITH, Veronica C., Department of Geological Sciences, California State University,
Fullerton, Fullerton, CA 92831, HELFRICH, Autumn L., Department of Environmental,
Geographical and Geological Sciences, Bloomsburg University of Pennsylvania, Bloomsburg,
PA 17815, WALLRICH, Blake M., Department of Geography, Geology, and the Environment,
Slippery Rock University of Pennsylvania, Slippery Rock, PA 16057 and MILLER, Calvin F.,
Department of Earth and Environmental Sciences, Vanderbilt University, Nashville, TN 37235,
[email protected]
Mafic to intermediate dikes and a mafic lopolith intrude the Miocene volcanic sequence of
Meadow Creek basin, southern Black Mountains, AZ (Thorson 1971; Liggett & Childs 1982; &
Schwat et al, Wallrich et al, Smith et al, Helfrich et al, [2016, GSA absts]). Contacts between
these intrusions and the highly silicic, pumice-rich Sitgreaves Tuff (STG) and the Meadow Creek
trachyte lava (MCL) display diverse effects of intrusions on host rocks and may provide insights
on how magma input may mobilize country rock.
Contact effects are highly variable. At contacts, MCL is locally indurated but generally
minimally affected by intrusion. STG at some contacts shows limited effects, but in general is
strongly indurated. In many places there are patches of dense glass that we interpret to be fused
or welded pumice fragments based on their sizes, shapes, and textures in thin section. Several
locations are characterized by massive (> 10 cm thick), obsidian-like dense glass that encloses
lithic fragments identical to those in the unmodified STG. Whole rock compositions (XRF) of
STG (minimally altered, strongly indurated, and glassy) at contacts (69 to 76 wt % SiO2) are
identical to those of unmodified STG (Wallrich et al 2016). Dense, glassy material - both patches
and massive - at contacts are compositionally similar to glass in unmodified SGT pumice (77 wt
% SiO2, 3-5 ppm Sr, 4-12 ppm Ba, 250-300 ppm Rb (SEM-EDS, LA-ICPMS). RhyoliteMELTS (Gualda & Ghiorso 2015) modeling of tuff margin contact glasses indicate a liquidus
temperature of 1000 °C at time of dike emplacement for very low P (5.4 MPa based on depth of
emplacement from the overlying stratigraphic thickness). Mafic dike temperatures are estimated
at ~1200°C (Smith et al 2016).
Plausible explanations of the dense glasses present at contacts include: (1) extremely efficient
heat transfer from intrusions leading to true melting of silicic pumice; (2) heating that raised
temperatures locally to above the glass transition but was insuffient to produce melting; welding
of pumice fragments and local rheomorphism was induced. Option (2) appears more likely, but
in either case effectiveness of intrusion-related mobilization of silicic glass (without requirement
for latent heat) is demonstrated (cf. Bindeman & Simakin 2014, Yellowstone; DuBray &
Pallister 1999, Turkey Creek caldera, AZ).
Abstract id# 286702, Requested: Poster
A COMPARISON OF SOIL QUALITY TO VEGETATION HEALTH IN THE COPPER
BASIN MINING REGION UTILIZING SMALL-FORMAT AERIAL PHOTOGRAPHY
ROATH, Hilary, FSU-Teach, Florida State University, Tallahassee, FL 32306 and
MANZANO, Michelle, Geological Sciences, California State University, Fullerton, CA 92831,
[email protected]
This study is a comparison of soil quality in the Tennessee Copper Basin mining region to levels
of vegetation health. Soil samples were taken from the Cherokee National Forest, Ducktown
Basin Museum and Copper Basin High School. Aerial photos were gathered to assess the health
of vegetation in the area surrounding the Copper Basin High School. Collected soil samples were
crushed into powder and then pressed into 40 mm diameter pellets. They were then chemically
analyzed by X-Ray Florescence spectrometry. In addition, sample locations were located on
various Landsat images from 1990 – 2015. For each soil sample location, the pixel value of the
infrared band was recorded using ArcMap. The infrared reflectance of each sample location was
then compared to the element concentrations in the soil samples. Results show that the
concentration (ppm) levels for P, K, Fe, Si, Al are fairly stable across the eleven sample sites, but
the concentrations (ppm) for Zn and Cu are not. The values for infrared reflectance also
generally increase and stabilize from 1990 – 2015.
Abstract id# 286871, Requested: Poster
EFFECTS OF RAINFALL ON COMMUNITY COMPOSITION AND STRUCTURE OF
CEDAR GLADES
SALONGA, Kirsten, Department of Ecology & Evolutionary Biology, University of Tennessee,
Knoxville, TN 37996 and DEAL, Daniel, Department of Science Education, Central Washington
University, Ellensburg, WA 98926, [email protected]
Cedar glades are treeless ecosystems with shallow soil or exposed limestone and are a hotspot of
plant endemism in the Southeast United States, predominantly in middle Tennessee. Soil depth is
a major factor which influences glade vegetation, and annual rainfall and temperature have
increased over time and are predicted to continue. This increase in rainfall has occurred due to
the “heat island” effect of Nashville. With an increase in water, we predicted that the number of
species, plant growth, and reproduction will increase due to self-thinning and additional water
supplies. We studied the effects of rainfall on community composition and structure of the Flat
Rocks State Natural Area. Four treatments of varying water regimes were established and
examined for differences in number of species, coverage, and flowers in plots with diameters of
50 centimeter. Data were analyzed by RMANOVA, and results showed that there was little
variation among treatments, with the number of species and amount of coverage remaining
constant. Results may be due to the inability of constructed shelters to restrict rainfall during
some storms due to high amounts of surface flow.
Abstract id# 283133, Requested: Poster
CONSTRAINING A CHRONOSEQUENCE OF FLUVIAL TERRACES USING SOIL
PROFILE ANALYSIS AND GIS MAPPING IN THE SANTA ROSALIA BASIN, BCS,
MéXICO.
HARTKE, Samantha1, PUGH, Andrew2, CAMACHO, Daniel3, ANTINAO, José Luis4 and
MARTINEZ GUTIERREZ, Genaro3, (1)Department of Geosciences, University of Texas at
Dallas, 800 W. Campbell Road, MC17, Richardson, TX 75080, (2)Mackay School of Earth
Sciences and Engineering, University of Nevada, Reno, 1664 N. Virginia Street, Reno, NV
89557, (3)Earth Sciences, Universidad Autonoma de Baja California Sur, Carretera al sur km
5.5, La Paz, 23080, Mexico, (4)Division of Earth and Ecosystems Sciences, Desert Research
Institute, 2215 Raggio Parkway, Reno, NV 89512, [email protected]
On the eastern coast of the Baja California Peninsula, marine terraces are incised by numerous
arroyos, along which fluvial terraces have developed. Through the NSF-funded Baja Basins
REU, fluvial terraces in Arroyo Santa Agueda and Arroyo Boleo of the Santa Rosalia region
were mapped and analyzed to better understand regional tectonic geomorphology related to the
Pleistocene evolution of the Santa Rosalia Basin. A soil chronosequence in these fluvial terraces
will be used to understand this evolution. South of this basin, in Mulege and Bahia Coyote,
previous work focused on marine terrace development, but not inland fluvial terraces.
During the initial phase of study, fluvial terraces were mapped using GIS in the field while soil
horizons of terraces lining each arroyo were observed, described, and sampled. Soil horizon
compositions will be determined by grain size analysis, XRD, and thin section microscopy. Soil
development indexes will be assigned to soil profiles characterized in the field following the
method outlined by Harden(1982) on the basis of various soil properties. GIS analysis of relative
soil development on terraces of varying elevations and locations will allow interpretation of
regional tectonics during terrace formation.
We expect to see varying levels of fluvial terrace soil development in Arroyos Santa Agueda and
Boleo despite corresponding elevations. Relative rates of terrace uplift compared with terrace
development will allow interpretation of differences in tectonic activity in the two catchments
which limit the Santa Rosalia basin to the south and north, respectively. The constraints provided
by this analysis will generate new insights into development of the Santa Rosalia basin. When
combined with absolute geochronology, this will be the first fluvial terrace chronosequence
developed for central Baja California, a powerful tool for regional paleoclimate and
geochronology studies in the future.
Reference: Harden, J., 1982, Geoderma, vol. 28, pg. 1-28.
Abstract id# 286974, Requested: Poster
HISTORIC LAND USE DISTURBANCES RECORDED IN SOIL PROFILES ALONG A
SLOPE IN THE SOUTHERN APPALACHIANS, WESTERN NORTH CAROLINA
EARLE, Stephanie, VASCIK, Bryce, WALTON, Quentin, LORD, Mark and KINNER, David,
Geosciences and Natural Resources, Western Carolina University, Cullowhee, NC 28723,
[email protected]
Throughout the southern Appalachians, anthropogenic land disturbances in the late 1800s
through much of the 1900s caused extensive soil erosion. Landscape and soil recovery rates from
these past disturbances influence vegetation, water pathways, and water quality today. The
purposes of this study were to determine the relation of soil physical and hydrologic properties to
slope position, and to historic land covers and uses. A specific goal of the study was to determine
the basic physical traits of soil profiles, including any evidence of soil truncation by erosion.
The study area, the Gribble Gap catchment (0.4 km2), is located in the headwaters of the Little
Tennessee River watershed in the mountains of western North Carolina. Soil parent materials are
saprolite developed from biotite-amphibole gneiss and colluvium. Logging and conversion of
woodlands to pasture in the early 1900s led to extensive soil erosion through the mid-1900s; this
land use history is common across the region.
Five soil profile sites were examined on a transect perpendicular to a slope from a ridgeline to
the valley floor, and an additional site was downstream on a fan surface. Soil horizons were
defined in the field, including depth to saprolite where present. Samples were analyzed for color,
percent of clay-silt-sand-gravel, and organic carbon content. Soil moisture sensors were installed
at each slope transect site at depths of 15, 35, and 75 cm.
At five sites, saprolite was found at depths of 75 to 185 cm. At the sixth site, on the valley floor
abutting the slope and 1.6 m from a small creek, gleyed soils from 90 to 115 cm deep sit on
coarse gravel, likely an old creek bottom. Soil profiles, especially on the upper slope, show
evidence of truncation as indicated by a thin A horizon and a shallow, reddish, clay-rich B
horizon. The valley-floor soil profile, however, is younger and appears to have a paleosol at 80
cm depth as indicated by a strong brown color (7.5YR 4/6) and high carbon content. We interpret
most of the upper slope to be truncated by historic soil erosion and the valley floor profile to be a
site of rapid deposition by products of soil erosion. Soil moisture data will be used to examine
soil properties and make inferences about hydrologic pathways and groundwater recharge
potential.
Abstract id# 285199, Requested: Poster
TESTING THE YOUNGER DRYAS IMPACT HYPOTHESIS USING ELEMENTAL AND
MAGNETIC SPHERULE ANALYSIS OF 12.9KA LAKE SEDIMENT FROM LAGUNA
CHAPALA, BC, MEXICO
THOMAS, Kaylee A., Department of Geosciences, University of Missouri at Kansas City,
Kansas City, MO 64110 and MUROWCHICK, James B., Geosciences, University of Missouri Kansas City, 5100 Rockhill Road, Room 420 Flarsheim Hall, Kansas City, MO 64110,
[email protected]
Lacustrine sediments deposited in Laguna Seca Chapala, located in central Baja California,
Mexico, span the Younger Dryas stadial. The Younger Dryas was an abrupt change in climate
that occurred approximately 12.9 ka and is hypothesized to have been triggered by a cometary
airburst or impact. Evidence of the impact has been found by others at nearly 40 localities in
North America. In North America, the YDB is coincident with the extinction of more than 40
species of megafauna and the demise of the Clovis paleoIndian culture.
This research examines the elemental composition and magnetic fraction of the lacustrine
sediments for indicators of an impact fallout horizon in the sedimentary sequence. We collected
49 samples (spanning 2 cm each) across two distinct grain-size boundaries that were bracketed
by optically stimulated luminescence (OSL) and radiocarbon dating reported by Davis (2003) to
be between 15 ka and 8 ka. X-ray diffraction analysis shows the sediment contains dominantly
quartz, sodic plagioclase, a small amount of microcline, and minor calcite. The samples were
homogenized and leached using double-distilled nitric acid and microwave digestion.. After
digestion, the leachates were diluted with 18MΩ water and analyzed by ICPMS for Ir, Fe, Ni,
Co, Mn and Ti.
Results show that the samples have high concentrations of Fe, likely due to detrital magnetite.
All samples contained <0.1ppb of Ir with no apparent spikes in concentration. Mn, Co, and Ni do
show spikes in concentration at two sample intervals (162-164 and 174-176cm below the base of
the overlying modern dune sands). The cause of those spikes is not known, but they do not
appear to be related to a possible fallout layer. Both of the spikes fall above a layer dated at
12.79±0.78ka by OSL dating. Results indicate that Laguna Chapala sediments do not preserve
evidence of meteoric impact.
Abstract id# 286126, Requested: Poster
ENVIRONMENTAL BASELINE STUDY FOR MANAGED SEDIMENT RELEASE FROM
THE LOWER RESERVOIR, ONEONTA CREEK, ONEONTA, NY
RICHARD, Emilie M.1, PLATT, Andrew S.2 and BRUNSTAD, Keith A.1, (1)Earth &
Atmospheric Sciences, SUNY Oneonta, 108 Ravine Pkwy, Oneonta, NY 13820, (2)Earth &
Atmospheric Sciences, SUNY Oneonta, 108 Ravine Pkwy., Oneonta, NY 13820,
[email protected]
The Lower Reservoir in Oneonta, NY is one of the city’s main sources of drinking water.
Storage capacity of the reservoir has decreased significantly over the years due to the increasing
sediment infill behind the dam. The city management is considering flushing sediment
downstream to restore the storage capacity of the reservoir. Limited research has been done to
assess the impact of dam removal or reservoir flushing on downstream ecosystems and water
quality. The goals of this study are to generate a comprehensive baseline data set for the
conditions of the stream prior to sediment release, and predict the potential impacts associated
with this practice.
Sedimentology, geomorphology, water chemistry, and biology of the stream were analyzed at
sample sites above and below the reservoir using standard methods. Water chemistry and stream
biology were assessed every 2-3 weeks to count for seasonal variations.
Pebble counts reaffirmed that the streambed and bar deposits contain primarily small boulders to
fine gravels. During dry conditions, there is little to no aggradation of sediments. After heavy
rain or snowmelt, discharge is so high that any accumulated fine sediments are carried out to the
Susquehanna River.
Electrical conductivity and total suspended solid concentrations increase downstream during
both low and high flow conditions, which is likely attributed to the increased anthropogenic
influences downstream and input from drainage ditch runoff. Nitrate concentration is 0.26 mg/L
in the reservoir, drops to zero directly below the dam, then increases to 0.64 mg/L farther
downstream. The pH remains consistently around 6.40 at all sites.
Preliminary analysis of aquatic insect taxa data suggests greater species richness above the
reservoir with 7 orders and 28 different families identified, and only 5 orders and 18 families
downstream. The decreased stream flow below the reservoir and the increased anthropogenic
influence at downstream sites potentially cause this trend.
The Lower Reservoir represents a common problem of many small reservoirs around the
country. Abruptly flushing large amounts of sediment accumulated behind the dams could cause
an unexpected response of the river ecosystem. Thus, long-term studies are needed to understand
the potential consequences of this reservoir management practice.
Abstract id# 287539, Requested: Poster
FAULT-ASSOCIATED DOLOMITIZATION IN THE ONONDAGA LIMESTONE IN
CENTRAL AND WESTERN NEW YORK
KITA, Andrew R., KREPPEL, Elizabeth, WILLIAMS, Lydia R. and NOLL, Mark R.,
Department of the Earth Sciences, SUNY College at Brockport, 350 New Campus Dr,
Brockport, NY 14420, [email protected]
One process for the formation of dolomite is the alteration of primary calcium carbonates with
Mg-rich fluids. Several studies (eg. Nurkhanuly et al. 2014) have found significant
dolomitization of limestones along faults. Fault networks control the flow of hydrothermal fluids,
therefore, the distribution and extent of dolomitization may be highly variable. Recent studies in
central and western New York State have identified networks of fault zones. One of the more
prominent fault zones that has long been identified is the Clarendon-Linden Fault which runs
approximately N-S through Batavia, NY. A total of 26 samples from 11 different quarries
running along a E-W transect that roughly parallels I-90 were analyzed for molar ratios of Ca
and Mg by ICP-AES. Most samples are not in close proximity to fault zones. These samples
show molar Mg percentages ranging from 1.97% to 2.86%, indicating low-Mg calcite. Those
more closely associated with faults, in particular the Clarendon-Linden fault show molar Mg
percentages of approximately 37%. While this is not pure dolomite, it indicates a significant
degree of alteration of the native limestone. The significance of the alterations associated with
the Clarendon-Linden fault zone is not known at this time.
Abstract id# 285379, Requested: Poster
MINERALOGICAL EVIDENCE OF AN EPITHERMAL EXHALATIVE ORIGIN OF THE
BOLEO CU-ZN-MN-CO MANTOS, SANTA ROSALIA, BAJA CALIFORNIA SUR,
MEXICO
DUVAL, Charles L., Geology and Environmental Geosciences, Northern Illinois University,
Dekalb, IL 60115, SUAREZ, Stephanie Elaine, Geological Sciences, University of Texas at
Austin, Jackson School of Geosciences, Austin, TX 78712 and MUROWCHICK, James B.,
Geosciences, University of Missouri - Kansas City, 5100 Rockhill Road, Room 420 Flarsheim
Hall, Kansas City, MO 64110, [email protected]
The Boleo Cu-Zn-Mn-Co manto deposits near Santa Rosalia, Baja California Sur, Mexico, are
hosted in a series of Pliocene conglomerates, altered tuffs, limestones, and evaporates in the
Santa Rosalia Basin. The mantos formed above coarse conglomerates at the bottom of the
overlying tuffaceous sandstones of the Boleo Formation, with five main mantos and at least eight
mineralized beds in detail. The ores have been mined since the mid-19th century, and advances in
extractive solution chemistry have resulted in the current major mining activity in the district.
Two models of formation of the manto mineralization have been presented. Wilson and Rocha
(1955) concluded that hydrothermal fluid rose along faults from the underlying Comondu
volcanics into the overlying Boleo Formation. The fluids spread laterally along conglomerate
beds, trapped beneath the less permeable tuffaceous sandstones, and deposited the ore
mineralization. A more recent model proposed by Conly et al. (2006, 2011) calls on venting of
hydrothermal fluids at the surface with accompanying deposition of the ore minerals both as
chemical sediments and as cements and replacements of underlying sediments by infiltrating
fluids in fluvial to near-shore marine environments. Our investigation of two of the mantos
provides evidence supporting Conly’s exhalative model.
Detailed examination of Manto 1 reveals sedimentary features such as syneresis cracks, small
ripples in laminated siltstones, and evidence of a highly oxidized evaporitic depositional
environment (hematitic halite-bearing siltstone). In Manto 2, below Manto 1, we found
sedimentary laminations, and deposits of laminated tufa with ore mineralization. In the
rhythmically banded gypsum beds at the eastern edge of the district, several thin heavy mineral
lag deposits of Cu-Co-Fe-Zn sulfides (possibly villimaninite and an unidentified Co-rich sulfide
with Cu and Fe) were found during SEM/EDS examination.
Based on the findings of the current investigation and those of previous studies, we conclude that
an epithermal exhalative process is a better model for the formation of the manto mineralization
than the dominantly subsurface lateral flow of fluids.
Abstract id# 287666, Requested: Poster
EVALUATING THE IMPORTANCE OF REGOLITH HETEROGENEITY ON CATCHMENT
HYDROLOGY IN GARNER RUN, SUSQUEHANNA SHALE HILLS CRITICAL ZONE
OBSERVATORY, PENNSYLVANIA, USA
SILVERHART, Perri H.1, ZHI, Wei2, XIAO, Dacheng2, DEL VECCHIO, Joanmarie3,
DIBIASE, Roman A.4 and LI, Li2, (1)Geology Department, Middlebury College, Middlebury,
VT 05753, (2)John and Willie Leone Family Department of Energy and Mineral Engineering,
The Pennsylvania State University, University Park, PA 16802, (3)Department of Geosciences,
Pennsylvania State University, University Park, PA 16802, (4)Department of Geosciences,
Pennsylvania State University, University Park, PA 16802; Earth and Environmental Systems
Institute, Pennsylvania State University, University Park, PA 16802,
[email protected]
Soil hydrologic properties determine how water, solutes, and sediment move through the near
surface environment and serve as important input parameters for watershed-scale hydrologic
models. While robust methods exist for characterizing the hydrologic properties of
homogeneous, fine-grained soils, it is less clear how to incorporate rocky soils into critical zone
models. Here we analyze the influence of regolith heterogeneity on catchment hydrology in
Garner Run, a sandstone subcatchment of Shavers Creek in the Susquehanna Shale Hills Critical
Zone Observatory, Pennsylvania. As a result of Pleistocene periglacial modification, Garner Run
exhibits a strong heterogeneity in surface cover ranging from clay-rich soils to unvegetated
boulder fields, which is not well captured by existing soil maps. Using a combination of new
high-resolution maps of surface cover, field measurements of hydrologic properties, and
preliminary model runs using the Penn State Integrated Hydrologic Modeling System (PIHM),
we evaluate model sensitivity to spatial heterogeneity in regolith cover characteristics of
sandstone landscapes in central Pennsylvania. Our results have implications for the interpretation
of local measurements of soil moisture in such landscapes, and for the application of large scale
soil maps in hydrologic models of upland landscapes.
Abstract id# 285428, Requested: Poster
USING INDUSTRY SEISMIC DATA TO MAP THE DISTRIBUTION OF DEEP-SEATED
FAULTS AND EVALUATE WHETHER THEY AFFECT HOLOCENE STRATA OF THE
LAKE PONTCHARTRAIN BASIN, LOUISIANA
CLARK, Shara L.1, FRANK, Joseph P.1 and KULP, Mark A.2, (1)Department of Earth and
Environmental Sciences, University of New Orleans, 2000 Lakeshore Dr., University of New
Orleans, New Orleans, LA 70148, (2)Department of Earth & Environmental Sciences,
University of New Orleans, 2000 Lakeshore Drive, New Orleans, LA 70148, [email protected]
Coastal land loss stemming from relative sea level rise (RSLR) is the most significant
environmental topic currently faced by southern Louisiana, and understanding the mechanisms
driving RSLR is fundamental to adapting effective, land loss mitigation efforts. For this reason,
an array of investigations into the processes responsible for coastal land loss and RSLR have
been conducted, yielding two distinct views. One position asserts that Holocene sediment
compaction is the primary process driving land-surface subsidence, whereas another position
contends that fault motion along deep-seated faults is a primary driving force. This study focuses
on whether deep-seated Cenozoic faults extend up section to faults that are known to offset
Pleistocene and Holocene strata within the Lake Pontchartrain Basin. Recently donated industry
2-D seismic data within Lake Pontchartrain provides an unique opportunity to map the
distribution of deep-seated faults and determine if they are linked to well-known near surface
faults that have been mapped previously with shallow, high-resolution seismic data. Work by
Roth (1999), identified five, typically down-to-the-south Pleistocene faults within Lake
Pontchartrain and provides a baseline of near surface fault distribution. To date this project has
identified 20 faults at depths of several thousand meters and several of these deep-seated faults
project upward to areas where Roth (1999) identified Pleistocene and Holocene fault offset. The
significance of this project is the opportunity to use industry seismic data and evaluate the role of
long-term geologic processes, such as faulting, in modern-day land loss of southern Louisiana.
Abstract id# 285744, Requested: Poster
DOES BIOCHAR IMPROVE DISTURBED, SANDY SOILS?
FAST, Kathleen M. and BODENBENDER, Brian E., Geological and Environmental Sciences,
Hope College, 35 E 12th St, Holland, MI 49423, [email protected]
We studied whether adding biochar to sandy, carbon-poor soil impacts plant growth. Biochar is
an organic compound composed mainly of black carbon and made by pyrolysis of organic
matter. Biochar is of interest as a possible soil amendment to alleviate stresses on agricultural
production due to its high water and nutrient retention capabilities, high cation exchange
capacity, high porosity that increases mycorrhizal growth, and ability to sequester carbon
dioxide.
We examined the growth of three different plant types, Avena sativa (common oat), Vigna
radiata (mung bean), and Raphanus sativus (cherry belle radish), in greenhouse and garden plot
experiments. In the greenhouse we used five different treatments of soil from a demolition site:
soil alone and soil mixed with 2%, 5%, 10%, and 20% biochar by mass. All biochar was washed
to remove ash and inoculated with compost tea before mixing. Four replicates of each species
were planted in individual pots of each of the five soil types for a total of 60 plants. Plants were
grown for 5 weeks and watered every other day. At the end of the growth period, A. sativa and V.
radiata plants were cut off at the soil surface and entire R. sativus plants were removed from
soil, then dried in a plant press before weighing. All 60 replicates produced plants, with no
statistically significant differences in oat and mung bean above ground biomass or radish whole
mass for any treatment.
In the garden experiment at a grassed-over former building site, we planted 10 seeds of each
plant in each of 5 plots: soil only, 3% compost by mass, 3% biochar by mass, and 3% and 5%
biochar inoculated with compost tea. Oats had 100% germination in all plots, while radishes
yielded 8, 7, 5, 9, and 7 plants respectively. For mung bean the control and compost plots yielded
only 2 and 4 plants while the biochar treatments yielded 7, 3, and 9 plants. Whereas all soil
treatments grew plants under controlled greenhouse conditions, the garden experiment, which is
ongoing, suggests that under more natural conditions biochar may influence germination and
survival.
Abstract id# 287007, Requested: Poster
FOLDING AS A POSSIBLE INDICATOR OF SUBSURFACE PALEOZOIC FAULTING,
CENTRAL TENNESSEE
HAN, Amber, Department of Geological Sciences, California State University, Fullerton, CA
92831 and FLORES, Jonathan, Department of Geosciences, Middle Tennessee State
University, Murfreesboro, TN 37132, [email protected]
The investigators searched for a subsurface fault in central Tennessee by searching for
macroscale fault propagation folds and fault-related fractures. They georeferenced existing 7.5’
geologic quadrangle maps, digitized the contact between the Ordovician Ridley limestone and
the overlying Ordovician Lebanon limestone, and extracted the elevation of the contact at
approx. 12,600 points from the National Elevation Dataset (NED). The investigators found a
syncline involving 35 m of structural relief and having a length of approx. 16.3 km. They
interpreted this syncline as a fold formed during the upward propagation of a north-side-down
fault striking 283 ̊. Sub-vertical and moderately-dipping joints parallel the fault south of
Murfreesboro, TN along Highway 231.
Abstract id# 285787, Requested: Poster
ROCK WEATHERING OBSERVED IN OUTCROPS AND IN BEDROCK EXPOSED BY
DEBRIS FLOWS: A PRELIMINARY INVESTIGATION OF GRANODIORITE
WEATHERING IN A LANDSCAPE CONTEXT
ROSS, Sean L., Red Rocks Community College, Lakewood, CO 80228 and ANDERSON,
Suzanne P., Department of Geography and INSTAAR, University of Colorado, UCB-450,
Boulder, CO 80309, [email protected]
Weathering of bedrock is a central facet of landscape development, yet surprisingly little is
known about processes or their rates. Rock weathering is a precursor to mobile regolith
formation, and hence sets the stage for sediment production, and therefore controls the pace of
landscape evolution. We explore rock weathering in Boulder Canyon in the Colorado Front
Range, where hillslopes comprise both bedrock outcrops and thin mobile regolith cover. The
canyon results from upstream propagation of a knickzone from the contact between the Boulder
Creek batholith and Mesozoic sedimentary rocks at the range front.
Rock weathering is expected to increase with time that rock has been exposed at the surface, and
to be promoted by burial under thin soil cover. We therefore made measurements at sites in
Boulder Canyon to test differing surface exposure ages and covered versus uncovered
conditions. We chose outcrops in the canyon from the mouth to the top of the knickzone to look
for the effect of surface exposure age; we hypothesize that degree of weathering will increase
with distance from the knickzone. To study the effect of soil cover, we examined bedrock
exposed by debris flows on steep (>25°) slopes during the September 2013 Front Range storm.
Based on models of soil production rate, we expect greater weathering in rock that has been
covered by mobile regolith, such as rock exposed by debris flows.
At each sample site, we used a Proceq SilverSchmidt hammer to test rock strength, measuring
rock rebound values along 5-20 m long transects. We also counted the number of fractures
crossing each transect. At selected sites, we collected samples for XRD mineralogical analysis.
In the survey of outcrops in the canyon, we found a slight decrease in rock strength with distance
from the knickzone. This accords with rock weathering increasing with time since the passage of
the knickzone. In the rock exposed by debris flows, however, we found that rock strength was
often greatest in the thalweg of the debris flow channel. We observed decreasing rock strength
from debris flow mouth to its initiation point. These observations suggest that debris flows scour
their flowpaths, removing weakened rock where the flux of sediment is greatest, thus
confounding our expectation of using the debris flow exposures to study rock weathering under
regolith cover.
Abstract id# 285807, Requested: Poster
DENUDATION RATE ANALYSIS OF HOLOCENE CARBONATES FROM ELEUTHERA,
BAHAMAS
JORDAN, Miranda M., Geology, Sam Houston State University, 1905 University Ave,
Huntsville, TX 77340 and SUMRALL, Jeanne Lambert, Geology, Blinn College, 902 College
Avenue, Brenham, TX 77833, [email protected]
Denudation rates were calculated for three eolian dunes on Eleuthera, Bahamas through field
measurements and lab analysis. One set of samples were gathered from North Twin Coves dune
on the Eastern side of the island, and two sets of samples were gathered from two separate dunes
located on the Southernmost tip of Eleuthera, collectively known as South Point and South Point
Dune. One portion of the set of samples were chiseled above a truncation surface, and the second
portion of the set of samples were chiseled from below the truncation surface. Five portions of
the above gathered samples were carbon dated; the age of the oldest dune was 7,004 years old
and the youngest portion of the youngest dune was 4,581 years old. It was determined that all
three dunes fall within the Holocene, with a gap of 2,400 years. The carbon dates were then
compared with field measurements to determine the rate of active denudation on the dunes
present on Eleuthera. South Point Dune was utilized for this calculation due to the active
denudation surface observed in the field. The calculated denudation rate for South Point Dune
was found to be 76 centimeters every thousand years. Portions of the samples were then analyzed
for pore space, grain size, grain shapes, and dominant allochems to determine if there were any
biological differences. Lastly, using field measurements, it was determined that the dominant
paleo-wind direction matches the Easterly Trade Winds present today. This data, along with all
other observed and calculated data collected in this study, will expand research into how
paleoclimate altered the carbonate topography within The Bahamas.
Abstract id# 285808, Requested: Poster
WINTER CHLORIDE BEHAVIOR IN OHIO RIVERS AND THE INFLUENCE OF LAND
USE AND CLIMATE
SHAFFER, Leighane N.1, ALEXANDER, Riley M.1, HELTERBRANDT, Faith L.1 and
FORTNER, Sarah K.2, (1)Environmental Science, Wittenberg University, Springfield, OH
45501, (2)Geology, Wittenberg University, Springfield, OH 45501, [email protected]
Studies suggest that an increase in salinity of a waterway can harm the habitat and the organisms
living in that habitat. Chloride concentrations at or above 250 mg/L are toxic to organisms.
Sources of chloride to watersheds include fertilizer, sewage, and road salt. Chloride levels in
urban areas are increasing, especially during the winter months. This study compares the average
chloride concentration over a week in February of 2016 of the Mad River, in Springfield, Ohio,
to the average chloride concentration for the winter of 2015 of the Scioto River, Muskingum
River, Honey Creek, and the Great Miami River using 8 hour sampling data from the National
Center for Water Quality Research at Heidelberg University, in Tiffin, Ohio. Mad River samples
were collected from February 23, 2016 to March 2, 2016. The February 2016 samples from the
Mad River contained less average chloride (25.3 mg/L) than all other samples in spite of having
the most urban land use (9.0%). The Scioto, which has a 4.6% urban land use, had the highest
average winter chloride concentration of 111.1 mg/L. There was no general relation between
watershed specific discharge and chloride yield. The study was further expanded to include the
analysis of chloride concentration and flow over a longer period (1996-2015). Flow generally
increases through time for all sites. Honey Creek and the Great Miami River exhibit a larger
increase in specific discharge over time. There is a general increase in chloride concentration
over time for the Scioto River, but no trend for other sites. Chloride yields exhibited a slight
decrease through time. Fewer snow events may have led to a decrease in road salt applications
and associated runoff. This work suggests that while land use largely explains differences
between comparisons made over the same time period, variation between years may reflect
changing deliveries associated with climate conditions. Excess chloride can harm habitats and
contaminate the ground water supply that humans depend on, and therefore more work should
evaluate the interplay between land use, climate, and chloride response.
Abstract id# 285891, Requested: Poster
DUCTILE FABRIC ANOMALIES CONCERNING THE ALLEGED ALEXANDER CITY
FAULT IN THE EASTERN BLUE RIDGE OF CENTRAL ALABAMA
BARKLEY, Morgan N. and HAWKINS, John F., Department of Geosciences, Auburn
University, 210 Petrie Hall, Auburn, AL 36849, [email protected]
The Alexander City Fault (ACF) is traditionally defined as a brittle-ductile strike slip fault
propagating through the Eastern Blue Ridge (EBR), and serving as the contact between the
Elkahatchee Quartz Diorite(EQD) and the Wedowee Group (WG). The trajectory and
characteristics of this fault tends to become more enigmatic as it approaches the Alabama
Coastal Plain. Detailed field mapping of a transect perpendicular to the contact of the EQD and
WG in the Elkahatchee Creek, south of Alexander City, Alabama confirms this to be an intrusive
contact rather than a fault emplacement. Shear fabric data (S and C) gathered along this transect
from the EQD and WG have calculated slip lines that produce populations with concentrations at
N33E, 11˚ and S27W, 05˚. These population’s local maxima aligns with S and C fabric data
previously reported for ductile portions of the ACF. Interestingly, this trend aligns with S and C
slip line data collected in the adjacent Our Town quadrangle lithologies, the Wedowee and
Emuckfaw Groups and the Kowaliga Gneiss. These data locations are not interpreted to have
been influenced by movement of the ACF and the S and C data are contributed to other regional
shearing events. This proves to be an interesting correlation. With the contact being intrusive and
slip line data showing strong correlations to other regional slip line populations that are not fault
related, where does this leave the ACF? Data suggests that the ACF does not cross this study
area as a ductile fault. Local S and C fabrics seen in the EQD and WG are not produced by
ductile movement along the ACF, but rather other regional shearing events are responsible;
however, this does not rule out a narrow brittle ACF propagating through this transect. Ongoing
detailed field mapping along the ductile sections of the ACF will help to explain the interesting
correlation between previously reported slip line data attributed to the ACF with other regional
slip line data currently not connected with the ACF.
Abstract id# 285985, Requested: Poster
PHOSPHOROUS AND SEDIMENT FLUX ANALYSIS IN AQUIA CREEK A SUBWATERSHED OF THE CHESAPEAKE BAY BASIN, VIRGINIA, USA
COXON, Taylor M., HOLLBERG, Coalter, ODHIAMBO, Ben K. and SOMERS, Hannah,
Earth and Environmental Sciences, University of Mary Washington, 1301 College Avenue,
Fredericksburg, VA 22401, [email protected]
Aquatic systems are negatively affected by excess input of phosphorus bound to sediments
generated by surficial and in-channel erosion and the release of P from wetland and floodplain
soils. This study examines stream water and wetland soils phosphorous levels in the basin of
Aquia Creek, a 3rd order tributary of the Potomac River (U.S.A). Bank erosion pins, analysis of
LIDAR data and historic aerial images, along with the Revised Universal Soil Loss Equation
(RUSLE) coupled with a sediment delivery ratio (SDR) were used in analyzing rill and inter-rill
sediment fluxes as well as internally generated stream bank sediments. Soil core properties
including pH, soil organic matter (SOM), cation exchange capacity (CEC), and sorption sites
including Fe, Al, Ca, Mg, and Mn were analyzed to understand the physiochemical conditions
that trigger release of P into the creek from its wetlands. Water samples were taken at six
different locations bi-weekly and total P ranged from 0.05 to 95.88 ng g-1, with elevated levels
occurring during the autumn and spring seasons. RUSLE results estimate total surficial erosion
losses of 55,082 Mg yr-1 with a total flux of 9,041.4 Mg yr-1. Bank erosion pin measurements
show that rates vary from 1.2 to 75.7 cm yr-1, with the highest values incurred along downstream
reaches draining urban areas. Stream bank soils total P content ranged from 2 to 16 µg g-1. The
preliminary result from 40 soil cores along 9 transects perpendicular to the stream flow in two
wetland sites shows that percent SOM and CEC were higher in the downstream site (30.8 ± 11%
and 16.8 ± 4.3 cmol/kg, respectively) compared to upstream site (2.56 ± 2.1% and 7.35 ± 1.3
cmol/kg). Soil total P was also greater in the downstream site with an average concentration of
17.9 ± 7.2 µg g-1 compared to 6.36 ± 4.3 µg g-1 upstream. The data suggests that acceleration of
runoff due to urbanization and subsequent increases in internal erosion rates may significantly
contribute to elevated phosphorus concentrations in Aquia Creek. Completion of this study will
provide insight into the relationship between P supplied from surficial and in-channel erosion
and P sorption-desorption dynamics in the wetland soils in a system affected by both
urbanization and sea level rise.
Abstract id# 285998, Requested: Poster
THERMOCHRONOMETRIC DATING OF MUSCOVITE AND ZIRCON FROM THE
TALLULAH FALLS DOME, NE GEORGIA
FRASER, Kelley, Department of Geology, Appalachian State University, 572 Rivers Street,
Boone, NC 28608, CASALE, Gabriele, Geology, Appalachian State University, 033 Rankin
Science West, 572 Rivers Street, Boone, NC 28608 and LEVINE, Jamie S.F., Geology,
Appalachian State University, 037 Rankin Science West, 572 Rivers Street, Boone, NC 28608,
[email protected]
The Tallulah Falls Dome is a 35 km long-axis elliptical foliation dome cored by NeoproterozoicOrdovician-aged metasedimentary rocks located within the Blue Ridge of northeastern Georgia.
Surrounding the dome are bodies of metasedimentary rocks of the Tallulah Falls Formation and
elongated Grenvillian-aged gneissic plutons. Previous models suggest that formation of the
Tallulah Falls Dome is the result of duplexing during Alleghanian collision. In order to better
understand the deformational history of the Tallulah Falls Dome we used two
thermochronometers: 40Ar/39Ar in muscovite, and fission track in zircon. These
thermochronometers have closure temperatures of ~340 ˚C and ~240 ˚C respectively. 40Ar/39Ar
cooling ages from this study and previously published data indicate that cooling below ~340 ˚C
in and around the dome occurred between 321-317 Ma. Because of their age, zircon grains from
the Tallulah Falls Dome contain high track densities, which makes the tracks indistinguishable
from each other using standard optical counting methods. Instead we use low etching times and
scanning electron microscopy to better distinguish fission tracks. We will use these zircon
fission-track ages to determine a cooling rate through the zircon fission track closure temperature
using both thermochronometers, as well as pre-existing hornblende 40Ar/39Ar data where
available. This cooling rate will allow us to distinguish between steady and slow cooling rates
consistent with erosion, or rapid cooling consistent with tectonic denudation processes.
Abstract id# 287264, Requested: Poster
A PRELIMINARY IN SITU AND BASIN-WIDE 10BE TCN STUDY OF THE STE.
FRANCOIS AND OZARK MOUNTAINS LANDSCAPE
REMINGA, Katy N., Department of Geology, Grand Valley State University, 001 Campus
Drive, Allendale, MI 49401, WEBER, John C., Dept. of Geology, Grand Valley State
University, 001 Campus Drive, Allendale, MI 49401, SEONG, Yeong Bae, Department of
Geography Education, Korea University, 145 Anam-ro, Seongbuk-Gu, Seoul, 02841, South
Korea and KIM, Dong Eun, Geography, Korea University, Anam-ro, Seongbuk-gu, Seoul,
Korea, Seoul, 136-701, South Korea, [email protected]
The Ozark Mountains, Missouri and Arkansas, pose a major geologic and geomorphic anomaly.
They form a topographically high, structurally uplifted “block” that exposes buoyant (?) midProterozoic granite-rhyolite basement rocks in the North American mid-continent. The Ste.
Genevieve fault bounds the Ozarks on its steepest and structurally highest northeastern side. We
are using 14 precisely surveyed in situ terrestrial cosmogenic 10Be samples of multi-level strath
terraces in “shut-ins” (Precambrian bedrock canyons) that span east to west the core of the Ozark
dome (i.e. the Ste. Francois Mountains) to determine river incision rates and exposure ages and
to test whether uplift is symmetric or asymmetric across the Ozarks. Sample analysis is in
progress. We will then perform a basin-wide 10Be analysis to compare the effects of lithology on
erosion, and to gauge overall (basin-wide) versus local (shut-ins) erosion rates. We incorporate
additional tectonic geomorphic data, obtained from DGPS surveys, high resolution DEMS,
created using GIS, and detailed geomorphic maps, to identifying active knick-point migration,
zones of anomalous stream steepness, etc. and to place the exposure ages, erosion/incision rates,
and exhumation rates in the context of this unique landscape.
Abstract id# 287369, Requested: Poster
ANTHROPOGENIC EFFECTS TO SAND DUNES ON BARRIER ISLANDS: BRAZOS
SANTIAGO PASS AND PORT MANSFIELD PASS, SOUTH PADRE ISLAND, TX
RUBIANO, Romeo R., ATKINSON, Andrew and HEISE, Elizabeth A., School of Earth,
Environmental & Marine Sciences, UTRGV, 1 West University Blvd, Brownsville, TX 78520,
[email protected]
Coastal dunes become well developed with onshore winds, sufficient sediment supply, and
plentiful vegetation to assist in stabilization of sand particles (Atkinson et al., 2015). The impacts
of large storms periodically change and affect topography and local structures (Pethick, 1984).
Dune stability produced by vegetation helps to provide protection of leeward habitats during
high storm surges (Tunnell et al, 2002). This study was conducted on Boca Chica Beach and on
the beaches South Padre Island, Cameron County, Texas providing 14 topographic transects of
sand dunes. The first set of seven of transects began on the most northern end of Boca Chica
Beach near the jetties at Brazos Santiago Pass and continuing every kilometer southward for
seven kilometers. The second set began near the jetties at the Port Mansfield Pass and continuing
every kilometer southward for seven kilometers. Both of these areas are undeveloped areas of the
Gulf Coast of Texas.
A comparison of beach-face, berms, storm scalps and sand dune height was taken into account
when comparing the data recorded. This study also compared 6 previously recorded profiles
from the developed area of South Padre Island, Texas and is focused on the difference of sand
dune height between undeveloped and developed locations on this barrier island. The dunes on
South Padre Island near Port Mansfield are much larger and are more mature than the dunes on
Boca Chica Beach. Overall, the displacements of dune profiles are shown to be rather similar
between undeveloped Boca Chica Beach and undeveloped South Padre Island and a highly
developed City of South Padre Island. We took into account natural longshore drift,
anthropogenic influences for the locations: including and not limited to jetty construction,
infrastructure, tourism, vehicular access to beaches, and beach nourishments that somewhat alter
the natural profile. It appears that Boca Chica Beach and the undeveloped area of South Padre
have healthy beach system with classic dune structures. The City of South Padre Island has
attempted to replenish its beach system to a natural state. Although this comparison provides
data that shows an ever-changing coastal environment, it is only natural that severe weather, i.e.
hurricanes, or seasonal thunderstorms, will drastically change each profile in the future.