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Articles 481 - 510 of 1925

Full-Text Articles in Sedimentology

Using Cross-Sets For Paleodischarge Estimation And Paleocurrent Vectors In The Parthenon Sandstone, Northwest Arkansas, Sean Robert Parry May 2017

Using Cross-Sets For Paleodischarge Estimation And Paleocurrent Vectors In The Parthenon Sandstone, Northwest Arkansas, Sean Robert Parry

Graduate Theses and Dissertations

In this thesis, set thicknesses are used to estimate the paleohydraulics (paleodischarge and give magnitudes for paleocurrent directions) of the ancient river system which deposited the Parthenon Sandstone in northwest Arkansas. Set thickness is the vertical thickness of a group of strata conformable series (Mckee and Weir, 1953); set thickness represents truncated dunes. The goal of this thesis is to: 1) obtain paleodischarge estimates of the Parthenon sandstone via cross-sets and compare the results with previously calculated discharge estimates which use basin area to discharge collation techniques and 2) use paleodischarge estimates calculated within this thesis to give magnitude to …


Mapping The Spatial-Temporal Variation In Ras Ghanada Seagrass Meadows And Sand Shoals Between 1996, 2006 & 2012, Ryan Brookbank Apr 2017

Mapping The Spatial-Temporal Variation In Ras Ghanada Seagrass Meadows And Sand Shoals Between 1996, 2006 & 2012, Ryan Brookbank

HCNSO Student Theses and Dissertations

Seagrass meadows offshore Ras Ghanada, as elsewhere, are an important component to the ecosystem providing numerous benefits to both aquatic and human life. This work focused on mapping the spatial and temporal distribution of seagrass meadows offshore Ras Ghanada using aerial photography acquired in 1996 and high-resolution satellite images captured in 2006 and 2012. The movements of sand shoals were also tracked, so as to further explain the dynamics of this ecosystem, as it is the area between the shoal crests that hosts the best developed seagrass meadows. The natural limiting factor for seagrass on the Ras Ghanada coastal shelf …


Slope, Grain Size, And Roughness Controls On Dry Sediment Transport And Storage On Steep Hillslopes, Roman A. Dibiase, Michael P. Lamb, Vamsi Ganti, Adam M. Booth Apr 2017

Slope, Grain Size, And Roughness Controls On Dry Sediment Transport And Storage On Steep Hillslopes, Roman A. Dibiase, Michael P. Lamb, Vamsi Ganti, Adam M. Booth

Geology Faculty Publications and Presentations

Existing hillslope sediment transport models developed for low-relief, soil-mantled landscapes are poorly suited to explain the coupling between steep rocky hillslopes and headwater channels. Here we address this knowledge gap using a series of field and numerical experiments to inform a particle-based model of sediment transport by dry ravel—a mechanism of granular transport characteristic of steep hillslopes. We find that particle travel distance increases as a function of the ratio of particle diameter to fine-scale (1m) topographic variability associated with rocky landscapes. Applying a 2-D dry-ravel-routing model to lidar-derived surface topography, we show how spatial patterns of local and nonlocal …


Mineralogical Analysis Of Aeolian Dune Deposits, White River Badlands, South Dakota, Megan O'Connor, Paul Baldauf Apr 2017

Mineralogical Analysis Of Aeolian Dune Deposits, White River Badlands, South Dakota, Megan O'Connor, Paul Baldauf

Biology Faculty Proceedings, Presentations, Speeches, Lectures

The goal of this study is to test our hypothesis that sand dunes in the White River Badlands (WRB), South Dakota, northern Great Plains, formed during one or more prolonged prehistoric droughts. WRB dune fields are located on tabletops north of the White River in southwestern South Dakota. These parabolic dunes have maximum relief of 30 m and open to the northwest, consistent with the dominant wind direction for the region. Currently, dunes are stabilized by a drought-adapted, mixed grass prairie community.

Sand dunes form when 1) prolonged drought kills prairie vegetation, allowing wind to erode and transport sediment, forming …


Results Of Test-Hole Drilling For Observation Well Planning In The Upper Loup Natural Resources District, Fall 2016, Douglas Hallum, Sue Olafsen Lackey Mar 2017

Results Of Test-Hole Drilling For Observation Well Planning In The Upper Loup Natural Resources District, Fall 2016, Douglas Hallum, Sue Olafsen Lackey

Conservation and Survey Division: Faculty and Staff Publications

The High Plains Aquifer underlies much of Nebraska (Figure 1). It is the primary source of groundwater within the Upper Loup Natural Resources District (ULNRD) of central Nebraska (Figure 2). Water derived from the aquifer is an important natural resource for the area and supplies water for recreation, wildlife and agriculture, as well as domestic, municipal, and industrial uses. A general lack of water level observations in the region (Figure 3), recently developed groundwater irrigated acres along the upper Calamus River (Figure 4), falling spring water levels measured in existing irrigation wells (Figure 5), and a stable to falling stream …


Lithology And Depositional Environments Of A Portion Of The Clays Ferry Formation (Middle And Upper Ordovician) Exposed At Silver Creek, Madison County, Kentucky, Autumn Murray, Walter S. Borowski Mar 2017

Lithology And Depositional Environments Of A Portion Of The Clays Ferry Formation (Middle And Upper Ordovician) Exposed At Silver Creek, Madison County, Kentucky, Autumn Murray, Walter S. Borowski

EKU Faculty and Staff Scholarship

We measure, describe, and interpret a carbonate stratigraphic section within the Clays Ferry Formation (Middle and Upper Ordovician) cropping out in Madison County, Kentucky (USGS Kirksville 7.5” quadrangle). Outcrops are exposed within the bed of Silver Creek along Ky 876 (Barnes Mill Road) from ~100 m downstream of where a bridge crosses the stream, then upstream and upsection for a distance of ~300 m over several sets of falls until bedrock exposure becomes sporadic to absent. We sampled the stratigraphic section at approximately half-meter intervals, also taking samples at lithology changes. We collected a total 18 samples, all of which …


The Fate Of Carbon In Sediments Of The Xingu And Tapajós Clearwater Rivers, Eastern Amazon, Dailson J. Bertassoli Jr., André O. Sawakuchi, Henrique O. Sawakuchi, Fabiano N. Pupim, Gelvam A. Hartmann, Michael M. Mcglue, Cristiano M. Chiessi, Matthias Zabel, Enno Schefuß, Tatiana S. Pereira, Rudney A. Santos, Samantha B. Faustino, Paulo E. Oliveira, Denise C. Bicudo Feb 2017

The Fate Of Carbon In Sediments Of The Xingu And Tapajós Clearwater Rivers, Eastern Amazon, Dailson J. Bertassoli Jr., André O. Sawakuchi, Henrique O. Sawakuchi, Fabiano N. Pupim, Gelvam A. Hartmann, Michael M. Mcglue, Cristiano M. Chiessi, Matthias Zabel, Enno Schefuß, Tatiana S. Pereira, Rudney A. Santos, Samantha B. Faustino, Paulo E. Oliveira, Denise C. Bicudo

Earth and Environmental Sciences Faculty Publications

The Xingu and Tapajós rivers in the eastern Amazon are the largest clearwater systems of the Amazon basin. Both rivers have “fluvial rias” (i.e., lake-like channels) in their downstream reaches as they are naturally impounded by the Amazon mainstem. Fluvial rias are widespread in the Amazon landscape and most of the sedimentary load from the major clearwater and blackwater rivers is deposited in these channels. So far, little is known about the role of Amazon rias as a trap and reactor for organic sediments. In this study, we used organic and inorganic geochemistry, magnetic susceptibility, diatom, and pollen analyses in …


The Tuscaloosa Marine Shale: Geologic History, Depositional Analysis, And Exploration Potential, Jessica D. Pair Feb 2017

The Tuscaloosa Marine Shale: Geologic History, Depositional Analysis, And Exploration Potential, Jessica D. Pair

Electronic Theses and Dissertations

The Tuscaloosa Marine Shale (TMS) was deposited across southern Louisiana and Mississippi during the Upper Cretaceous. The study focuses on a core region containing vast deposits of Cretaceous-aged sediments that have economic importance for oil and gas exploration. This region has been conventionally drilled for decades, focusing on the recovery of the Cretaceous hydrocarbons. Explorers within this region had traditionally targeted the massive sand units of the Lower and Upper Tuscaloosa Group while neglecting the middle Tuscaloosa Marine Shale unit. With the onset of unconventional drilling technology, new explorers to the region have begun to delineate the Tuscaloosa Marine Shale’s …


Basic Meteorological Data Derived 30-Year Normas (1981-2010) Of Actual Evapotranspiration Rates In Nebraska, Usa, Jozsef Szilagyi Feb 2017

Basic Meteorological Data Derived 30-Year Normas (1981-2010) Of Actual Evapotranspiration Rates In Nebraska, Usa, Jozsef Szilagyi

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Petrographical And Geochemical Changes In Bosnian Stalagmites And Their Palaeo-Environmental Significance, Veronica Chiarini, Isabelle Couchoud, Russell Drysdale, Petra Bajo, Simone Milanolo, Silvia Frisia, Alan Greig, John Hellstrom, Jo De Waele Jan 2017

Petrographical And Geochemical Changes In Bosnian Stalagmites And Their Palaeo-Environmental Significance, Veronica Chiarini, Isabelle Couchoud, Russell Drysdale, Petra Bajo, Simone Milanolo, Silvia Frisia, Alan Greig, John Hellstrom, Jo De Waele

International Journal of Speleology

Detailed petrographic observations have been coupled with trace element and δ13C - δ18O analyses in order to investigate their dynamics in two Holocene Bosnian speleothems. The potential of this multiproxy approach in providing a means to extract palaeo-environmental information from stalagmites whose stable isotope signals are noisy and without obvious trends has been tested. The studied stalagmites are mostly characterized by columnar microcrystalline fabric. At the sub-millimetre scale of lamination, different microcrystalline columnar sub-types (open and closed) have been detected and classified on the basis of the observed porosity and the crystallite size. The presence of …


Mono Lake Data, Larry V. Benson Jan 2017

Mono Lake Data, Larry V. Benson

United States Geological Survey: Datasets

Mono Lake Basin Data\ Depth CalAge TIC TOTC TOC 13C 18O

Mono Lake short cores.xlsx 03.03.2014 19:59:44 0.06 xlsx

Depth PSV age 18O 13C

TIC for Wilson Crk Fm.xlsx 02.03.2014 16:07:10 0.03 xlsx

Ostracode 18O and TE data Wilson Crk Fm.xlsx 10.11.2017 17:43:18 0.12 xlsx

Depth, calendar age, TIC, TOTC, TOC, 13C, and 18O of Mono Lake short cores were reported in:

Benson, L., Linsley, B., Smoot, J., Mensing, S., Lund, S., Stine, S., and Sarna-Wojcicki, A., 2003, Influence of the Pacific Decadal Oscillation on the climate of the Sierra Nevada, California and Nevada: Quaternary Research. Quaternary Research …


Summer Lake Basin Data, Larry V. Benson Jan 2017

Summer Lake Basin Data, Larry V. Benson

United States Geological Survey: Datasets

Summer Lake Basin

Name Date modified Time modified Size MB Extension

Summer Lake Basin\

Depth PSV Age 13C 18O Summer Lake B&B core.xlsx 03.03.2014 16:51:12 0.03 xlsx

In the Summer Lake Basin folder:

Depth, PSV age, 18O, 13C data for Summer Lake core B&B are reported in:

Benson, L., Lund, S., Negrini, R., Linsley, B., and Zic, M. 2003. Response of North American Great Basin lakes to Dansgaard-Oeschger oscillations. Quaternary Science Reviews 22: 2,239-2,251.

General Comment: In most cases an age model based on 14C analyses is not included with the datasets although ones were created for …


Morpho-Sedimentary Characteristics Of Proximal Gravel Braided River Deposits In A Froude-Scaled Physical Model, Peter Ashmore, Tobias Gardner, Pauline Leduc Jan 2017

Morpho-Sedimentary Characteristics Of Proximal Gravel Braided River Deposits In A Froude-Scaled Physical Model, Peter Ashmore, Tobias Gardner, Pauline Leduc

Geography & Environment Publications

A Froude‐scaled physical model of a proximal gravel‐bed braided river was used to connect the river morphological characteristics, and sedimentary processes and forms, to deposit geometry. High resolution continuous three‐dimensional topographic data were acquired from sequential photogrammetric digital elevation models paired with grain‐size surface maps derived from image analysis of textural properties of the surface. From these data, the full three‐dimensional development of the braided river deposit and grain‐size sorting patterns was compiled over an experimental time period of 41 h during which the model river reworked a large portion of the braided channel. The minimum surface of the deposit …


Great Basin Surface Water And Precipitation Isotope Data, Larry V. Benson Jan 2017

Great Basin Surface Water And Precipitation Isotope Data, Larry V. Benson

United States Geological Survey: Datasets

In the Great Basin Surface Water and Precipitation Isotope Data folder:

Farad, Nixon, and Pyramid Lake 18O data were reported in:

Benson, L.V., 1994, Stable isotopes of oxygen and hydrogen in the Truckee River-Pyramid Lake surface-water system. 1. Data analysis and extraction of paleoclimatic information: Limnology and Oceanography, vol. 39, p. 344-355. https://digitalcommons.unl.edu/usgsstaffpub/1015

Spring chemistry around Pyramid Lake data were reported in:

Benson, L.V., 1994, Carbonate deposition, Pyramid Lake subbasin, Nevada: 1. Sequence of formation and elevational distribution of carbonate deposits (tufas): Palaeogeography, Palaeoclimatology, Palaeoecology, vol. 109, p. 55-87.

Benson, L.V., Kashgarian M., and Rubin, M., 1995, Carbonate deposition, …


2016 Nebraska Water Leaders Academy - Final Report, Mark E. Burbach, Connie Reimers-Hild Jan 2017

2016 Nebraska Water Leaders Academy - Final Report, Mark E. Burbach, Connie Reimers-Hild

Conservation and Survey Division: Faculty and Staff Publications

The effective management of Nebraska’s water resources is evermore challenged by variations in weather, climate, technology, socioeconomic policies, and regulation. Anthropogenic climate change, declining water tables and stream flows, increasing demands on freshwater, aging water infrastructure, fiscal constraints, and impacts on aquatic organisms are particularly imminent challenges in Nebraska and around the world (Pahl-Wostl et al., 2013; Pittock et al., 2008; USACE, 2010). Sustaining freshwater ecosystem services in the face of emerging environmental threats presents an immense societal dilemma worldwide (Pittock et al., 2013; Rockström et al., 2009, Millenium Ecosystem Assessment, 2005). The rapidly changing conditions of water resources in …


Paleoecology Of Foraminifera From The Late Miocene - Early Pliocene Pullen And Saint George Formations, Northwestern California, Trenton J. Ryan Jan 2017

Paleoecology Of Foraminifera From The Late Miocene - Early Pliocene Pullen And Saint George Formations, Northwestern California, Trenton J. Ryan

Cal Poly Humboldt theses and projects

The Pullen and Saint George formations are coeval late Miocene-early Pliocene sedimentary formations in northwestern California. The type localities of both formations were studied from a micropaleontologic perspective that focused primarily on Foraminifera, but with additional observations of other fossil groups to reconstruct their past depositional environments. The results obtained in this study provided a photomicrographic inventory of the microfossils from both formations, aided in investigating changes in paleobathymetry of the formations during the late Miocene and early Pliocene based on Foraminifera, and allowed for interpretation of paleoecological signals from the foraminiferan associations. Foraminifera have not been previously described in …


Lateral Heterogeneity And Architectural Analysis Of The Wall Creek Member Of The Upper Cretaceous (Turonian) Frontier Formation, John Zupanic Jan 2017

Lateral Heterogeneity And Architectural Analysis Of The Wall Creek Member Of The Upper Cretaceous (Turonian) Frontier Formation, John Zupanic

Graduate Student Theses, Dissertations, & Professional Papers

The Upper Turonian Wall Creek Member (WCM) of the Frontier Formation is part of a series of marine sandstones that were deposited on the western flank of the Cretaceous Western Interior Seaway (KWIS). The KWIS was a low accommodation shallow-marine foreland basin system that included many large deltaic complexes on its western margin. Deposition of WCM deltaic deposits was strongly influenced by fourthorder glacioeustatic cycles, oceanographic circulation patterns, and tectonics related to the active Sevier fold and thrust belt to the west. An in-depth field study of the WCM was performed on the western flank of the Powder River Basin …


Owens Lake Core Data, Larry V. Benson Jan 2017

Owens Lake Core Data, Larry V. Benson

United States Geological Survey: Datasets

In the Owens Lake core data folder:

14C ages for cores OL84 and OL90 were reported in:

Benson, L.V., Burdett, J.W., Kashgarian, M., Lund, S.P., Phillips, F.M., and Rye, R.O., 1996, Climatic and hydrologic Oscillations in the Owens Lake basin and adjacent Sierra Nevada, California: Science, vol. 274, p. 746-749.

Benson, L.V., 1999, Records of millennial-scale climate change from the Great Basin of the Western United States: In Clark, P., Webb, R., Keigwin, L., eds., Mechanisms of Global Climate Change at Millennial Time Scales, American Geophysical Union Monograph 112, p. 203-225.

Benson, L., 2003, Western Lakes: Chapter 9 in …


Paleomagnetic Secular Variation (Psv) Ages Of Wilson Crk, Plc08-1, Bl04-4, Ol90-1 And 2, Larry V. Benson Jan 2017

Paleomagnetic Secular Variation (Psv) Ages Of Wilson Crk, Plc08-1, Bl04-4, Ol90-1 And 2, Larry V. Benson

United States Geological Survey: Datasets

In the paleomagnetic secular variation (PSV) ages folder:

The data for OL90-1 and 2 have not been published

The data for PLC08-1 are reported in:

Benson, L.V., Smoot, J.P., Lund, S.P., Mensing, S.A., Rye, R.O., 2013. Insights from a synthesis of old and new climate-proxy data from the western Lahontan Basin for the period 48 to 11.5 ka. Quaternary International310, 62-82.

Lund, S., Benson, L., Negrini, R., Liddicoat, J., Mensing, S., 2016. A full-vector paleomagnetic secular variation record (PSV) from Pyramid Lake (Nevada) from 47-17 ka: Evidence for the successive Mono Lake and Laschamp Excursions. Earth and Planetary Sciences …


Pyramid And Winnemucca Lake Basin Carbonate Data, Larry V. Benson Jan 2017

Pyramid And Winnemucca Lake Basin Carbonate Data, Larry V. Benson

United States Geological Survey: Datasets

In the Pyramid and Winnemucca lake basin carbonate data folder:

New unpublished and previously published 14C and calibrated ages for materials in the Winnemucca Caves are reported in the table and in the references listed below the table

14C and calibrated ages for Winnemucca Lake Basin carbonates are reported in:

Benson, L.V., Hattori, E.M., Southon, J., Aleck, B., 2013. Dating North America’s oldest petroglyphs, Winnemucca Lake subbasin, Nevada. Journal of Archaeological Science 40, 4466-4476.

Tufa 87Sr, 18O, and 13C data are reported in:

Benson, L.V., Smoot, J.P., Lund, S.P., Mensing, S.A., Rye, R.O., 2013. Insights …


Reconstructed Discharge For Truckee River, Larry V. Benson Jan 2017

Reconstructed Discharge For Truckee River, Larry V. Benson

United States Geological Survey: Datasets

Reconstructed Discharge for Truckee River

Name Date modified Time modified Size MB Extension

Reconstructed Discharge Truckee R\ Reconstructed Discharge for Truckee River.xlsx 11.11.2017 22:40:52 0.02 xlsx

Reconstructed discharge of the Truckee River was made considering losses to evaporation in all upstream reservoirs and corrected for diversion from the Derby Dam to the Newlands area. These data were never previously published.

General Comment: In most cases an age model based on 14C analyses is not included with the datasets although ones were created for the original publications. Given the general problems with 14C ages in the lakes of the …


Walker Lake Basin Data, Larry V. Benson, Steve P. Lund Jan 2017

Walker Lake Basin Data, Larry V. Benson, Steve P. Lund

United States Geological Survey: Datasets

Walker Lake Basin Data

Name Date modified Time modified Size MB Extension

Walker Lake Core 84-8 isotope and age data.xls 27.01.2018 15:25:52 0.03 xls

Walker Lake core WL002 PSV age and chemical data.xlsx 09.02.2018 20:04:50 0.03 xlsx

In the Walker Lake Basin folder:

Depth, 14C age (not corrected for reservoir effect), 18O, 13C data for core 84-8 are reported in:

Benson, L. V., 1988, Preliminary paleolimnologic data for the Walker Lake subbasin, California and Nevada: United States Geological Survey Water-Resources Investigations Report 87-4258, 50 p. Palaeogeography, Palaeoclimatology, Palaeoecology 240: 497-507.

Depth, PSV age, TIC , 18O, …


Pyramid Lake Core Data, Larry V. Benson Jan 2017

Pyramid Lake Core Data, Larry V. Benson

United States Geological Survey: Datasets

Pyramid Lake Core Data

14C and calibrated ages for core PLC08-1.xlsx 01.03.2014 19:45:30 0.01 xlsx

14C and calibrated ages for core PLC92B.xlsx 04.03.2014 16:41:30 0.01 xlsx

14C and calibrated ages for core PLC97-3.xlsx 01.03.2014 19:50:48 0.01 xlsx

CalKa Depth TOC TIC 18O 13C for PLC97-1.xlsx 09.11.2017 20:51:22 0.04 xlsx

Depth 14CAge Corrected 14C AGE CAL Age PLC98-4.xlsx 15.11.2017 18:26:12 0.01 xlsx

Depth 180 13C TOTC TOC TIC porosity CYBP Box Core PLB98-2.xlsx 01.03.2014 20:00:46 0.01 xlsx

Depth CalAge TIC TOTC TOC 13C 18O PLC98-4.xlsx 02.03.2014 00:32:20 0.05 xlsx

Depth Equivalent Depth in PLC08-1 PSV age 180 13C TIC TOC for …


Depositional Controls And Sequence Stratigraphy Of Lacustrine To Marine Transgressive Deposits In A Rift Basin, Lower Cretaceous Bluff Mesa, Indio Mountains, West Texas, Andrew Anderson Jan 2017

Depositional Controls And Sequence Stratigraphy Of Lacustrine To Marine Transgressive Deposits In A Rift Basin, Lower Cretaceous Bluff Mesa, Indio Mountains, West Texas, Andrew Anderson

Open Access Theses & Dissertations

Successful hydrocarbon exploration in former rift basins of the South Atlantic pre-salt has generated interest in understanding depositional, diagenetic, and stratigraphic controls on pre-salt deposits. However, most studies to date have focused on attributes and controls on presalt lacustrine carbonate reservoir systems and little work has been done on the overlying marine sealing facies. Currently our standard sequence stratigraphic model of marine transgression of rift systems involves a single pulse of marine flooding over fluvially-incised valleys resulting in backstepping of fluvial and estuarine siliciclastic facies within the erosionally confined zone of an incised valley. However, the pre-salt systems of the …


Nebraska Statewide Groundwater-Level Monitoring Report 2016, Aaron R. Young, Mark E. Burbach, Leslie M. Howard, Michele M. Waszgis, R. Matthew Joeckel, Sue Olafsen Lackey Jan 2017

Nebraska Statewide Groundwater-Level Monitoring Report 2016, Aaron R. Young, Mark E. Burbach, Leslie M. Howard, Michele M. Waszgis, R. Matthew Joeckel, Sue Olafsen Lackey

Conservation and Survey Division: Faculty and Staff Publications

The term “groundwater” has come to be all but synonymous with Nebraska. Nearly three-quarters of the volume of the High Plains aquifer lies beneath the State, and groundwater maintains our streams, our ecosystems, our people, and our vitally important agricultural economy. Although Nebraska’s total groundwater resource is vast, it is also quite vulnerable to changes induced by natural processes and by humankind, necessitating a long-term commitment to wise management through informed decision making. Monitoring, studying, and reporting are the essential basis for such management and, ultimately, for meeting the myriad challenges presented by change.

The personnel of the Conservation and …


Stratigraphic, Geochemical, And Geochronological Analysis Of The Wolfcamp-D Interval, Midland Basin, Texas, Zachary S. Perlman Jan 2017

Stratigraphic, Geochemical, And Geochronological Analysis Of The Wolfcamp-D Interval, Midland Basin, Texas, Zachary S. Perlman

Theses and Dissertations--Earth and Environmental Sciences

Subsurface data derived from ~388 ft of drill core from Martin County (TX) were used to understand the depositional setting of the Wolfcamp-D, a petroleum producing interval in the Midland Basin. Elemental geochemistry collected via x-ray fluorescence revealed a highly variable depositional history marked by the deposition of diverse siliciclastic and carbonate lithofacies. Integration of multiple datasets resulted in the interpretation of nine lithofacies, whose deposition appears cyclical. Correlations between molybdenum and total organic carbon indicate slow recharge of bottom waters and anoxic/euxinicconditions within the basin. The presence of phosphatic nodules coinciding with siliceous black mudrocks suggested high levels of …


The Oligocene West Elk Breccia: Evidence For Massive Volcanic Debris Avalanches In The Eastern Gunnison River Valley, West-Central Colorado, U.S.A., Patrick J. Whalen Jan 2017

The Oligocene West Elk Breccia: Evidence For Massive Volcanic Debris Avalanches In The Eastern Gunnison River Valley, West-Central Colorado, U.S.A., Patrick J. Whalen

Theses and Dissertations--Earth and Environmental Sciences

The West Elk Breccia has been studied since the late 1800’s with many interpretations regarding its origin. One unrecognized possibility is that parts of it are debris-avalanche deposits. This study has recognized evidence for this interpretation at three scales: volcano scale, outcrop scale, and intra-outcrop scale. At the volcano scale, a scarp in the old volcano reveals underlying Mesozoic bedrock, suggesting sector collapse. At the outcrop scale, megablocks of the original edifice, up to hundreds of meters in length, have atypical orientations and are surrounded by a gravel matrix. At the intra-outcrop scale, jigsaw-fit fracturing and rip-up clasts are common …


Sedimentary Responses To Growth Fault Slip And Clay Shrink And Swell Induced Elevation Variations: East Matagorda Peninsula, Texas, Wei Ji Jan 2017

Sedimentary Responses To Growth Fault Slip And Clay Shrink And Swell Induced Elevation Variations: East Matagorda Peninsula, Texas, Wei Ji

Theses and Dissertations--Earth and Environmental Sciences

East Matagorda Peninsula in southwestern Texas is characterized geologically by active, regional-scale and near-surface growth faulting. Decimeter scale (up to 0.42 m) vertical displacement was recorded at the study site over a period of four years, not believed to be associated with growth faulting. This research tested the hypotheses that fault slip rates were correlated with sediment accumulation rates, and that the observed vertical displacement was produced by shrink-and-swell clays in near surface sediments. To quantify sediment accumulation rates, a suite of radionuclides (7Be, 137Cs, and 210Pb) were used. To understand the effects of shrink-and-swell clays, …


Fluvial-Lacustrine Processes Shaping The Landforms Of The Distal Paraguay Fluvial Megafan, Edward Limin Lo Jan 2017

Fluvial-Lacustrine Processes Shaping The Landforms Of The Distal Paraguay Fluvial Megafan, Edward Limin Lo

Theses and Dissertations--Earth and Environmental Sciences

Tropical wetlands such as the Pantanal help regulate global biogeochemical cycles, but climate change is modifying these environments. Controls on environmental changes can potentially be assessed from ancient, well-dated lacustrine sedimentary records. An integrated field and laboratory approach was undertaken to study the limnogeology of Lake Uberaba in the northern Pantanal, and test whether the lake has preserved a reliable record of environmental change in its strata. This study was designed to understand how the basin accumulates sediment and to assess its sensitivity to hydroclimatic variability. The data showed that modern Lake Uberaba is a highly dynamic, freshwater fluvial-lacustrine basin. …


Preservation Of Sea Anemone Burrows In Silurian (~432 Million Years Old) Carbonate Rocks Of Southeastern Indiana, Usa, Marissa Tomin Jan 2017

Preservation Of Sea Anemone Burrows In Silurian (~432 Million Years Old) Carbonate Rocks Of Southeastern Indiana, Usa, Marissa Tomin

Williams Honors College, Honors Research Projects

Preservation of trace fossils (ichnofossils) in siliciclastic environments is often quite different from preservation in carbonate environments, representing an important source of variation that must be well understood in order to enhance interpretations of paleoenvironments and paleoecology. This study focuses on Conostichus, a relatively common burrow constructed by solitary sea anemones. These trace fossils are generally well-preserved (i.e., they display detailed external features) in siliciclastic rocks but are typically little more than conical masses in carbonate rocks. However, certain specimens recovered from the middle Silurian Massie Formation at the Napoleon quarry of southeastern Indiana are composed entirely out of …