Geology Commons^™

Late Paleozoic Cyclic Sedimentation In Southeastern Nebraska: A Field Guide, Roger K. Pabian, Robert F. Diffendal Jr.

Conservation and Survey Division: Faculty and Staff Publications

A field guide to Late Paleozoic cyclic sedimentation in southeastern Nebraska.

Bazile Triangle Groundwater Quality Study, David C. Gosselin

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Facts And Figures About Nebraska Rivers, Ray Bentall

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Elemental Relationships In Rock Varnish As Seen With Scanning Electron Microscopy And Energy Dispersive X-Ray Elemental Line Profiling, Robert Raymond Jr., Steven L. Reneau, Charles D. Harrington

Scanning Microscopy

The heterogeneous nature of rock varnish requires a thorough understanding of elemental and mineralogic compositions before chemical variability of rock varnish may be confidently related to varnish age or to past geochemical environments. Elemental relationships in rock varnish were examined using scanning electron microscopy in conjunction with an elemental line profiling routine using semi-quantitative, energy-dispersive x-ray analysis. Results of our analyses suggest: 1) variations in cation concentrations used in varnish cation-ratio dating relate more specifically to variations in detritus concentration within the varnish than to element mobility as defined by weathering indices; 2) Mn:Fe ratios may be a poor indicator …

Scanning Electron Microscopic Analysis Of Rock Varnish Chemistry For Cation-Ratio Dating: An Examination Of Electron Beam Penetration Depths, Steven L. Reneau, Roland C. Hagan, Charles D. Harrington, Robert Raymond Jr.

Scanning Microscopy

Rock varnish is a microns-thick manganese- and iron-rich coating that forms on exposed rock surfaces in arid and semi-arid environments, and empirical correlations of the varnish cation ratio (K+Ca):Ti with age have been used to estimate ages of geomorphic surfaces. One method of obtaining varnish chemistry for cation-ratio dating involves scanning electron microscope (SEM) energy dispersive x-ray (EDX) analysis of natural varnish surfaces. The chemical analyses of rock varnish with SEM/EDX utilize a sequence of accelerating voltages to vary penetration depths into the sample. Using elemental x-ray maps of natural varnish surfaces obtained by SEM/EDX analysis, penetration into the substrate …

Barium Concentration In Rock Varnish: Implications For Calibrated Rock Varnish Dating Curves, C. D. Harrington, D. J. Krier, R. Raymond Jr., S. L. Reneau

Scanning Microscopy

Cation-ratio dating of rock varnish is a recently developed technique for obtaining surface exposure ages of a wide variety of geomorphic surfaces. As originally proposed, the technique utilizes a ratio among minor cations [(K+Ca)/Ti] in rock varnish. Although this varnish cation ratio is related to the Ti concentration, it can also be affected by the presence of Ba that may be partially included in the analyzed concentration of Ti. Barium is a minor constituent found in virtually all rock varnishes sampled from the Lake Mead area, Las Vegas Valley, and the Crater Flat region of southern Nevada. Barium is heterogeneously …

Geologic Map Showing Configuration Of The Bedrock Surface, North Platte, 1 ° X 2 ° Quadrangle, Nebraska, Robert F. Diffendal Jr.

Robert F. Diffendal, Jr., Publications

The map area, in west-central Nebraska, is largely covered by surficial deposits of eolian sand, loess, and alluvium ranging in age from Holocene to Pliocene. Holocene and late Pleistocene(?) eolian sand, as much as 300 ft (91 m) thick, covers most of the area north of the North Platte and Platte Rivers, and also covers a small area south of those rivers. The Peoria Loess of Quaternary age overlies most of the remaining upland north of the Platte River in southwestern Logan, northeastern Lincoln, and much of western Custer and extreme northwestern Dawson Counties. Loess also mantles the divide between …

Ontong Java Plateau, Leg 130: Synopsis Of Major Drilling Results, W. H. Berger, Loren W. Kroenke, Larry A. Mayer, Shipboard Scientific Party

Affiliate Scholarship

Sixteen holes were drilled at five sites on the northeastern flank of Ontong Java Plateau during Leg 130 (Sites 803 through 807). All of these sites are near the equator, but are at different depths (803: 02°26.0'N, 3410 m; 804: 01°00.3'N, 3861 m; 805: 01°13.7'N, 3188 m; 806: 00°19.1'N, 2520 m; and 807: 03°36.4'N, 2805 m). One of our goals was to obtain a depth transect of Neogene carbonate deposition for reconstructing the history of ocean climate, chemistry, and productivity, and for understanding the origin of acoustic reflectors. Another goal was to achieve considerable penetration into basement for elucidating the …

High-Resolution, Whole-Core Magnetic Susceptibility Data From Leg 130, Ontong Java Plateau, John A. Tarduno, Larry A. Mayer, Robert Musgrave

Affiliate Scholarship

High-resolution, whole-core magnetic susceptibility data, recorded at 3-cm intervals, were obtained for advanced hydraulic piston (APC) cores at Sites 805, 806, and 807 of Leg 130 on the Ontong Java Plateau. In this initial report, we present a preliminary evaluation of these data for their use in core correlations and paleoclimatic studies. The data allow detailed intrasite correlations between the offset APC cores and provide a means for intersite correlations of Pleistocene sediments. Variations in magnetic susceptibility values probably mirror variations in terrestrial influx and may act as proxy indicators of climate. Highly coherent cyclicity, representing Milankovitch orbital frequencies, is …

Chemical Analyses Of Water From Selected Wells And Springs In The Yucca Mountain Area, Nevada And Southeastern California, P. W. Mckinley, M. P. Long, Larry Benson

United States Geological Survey: Publications

Chemical analysis of water samples from 279 wells and springs in the Yucca Mountain area are presented. Where data are available, this report includes: site location expressed as Nevada Central Coordinates and latitude and longitude; source of data; name of analyzing laboratory; geologic unit from which water was obtained; lithology; water use; elevation of well or spring; well depth; depth to water; time pumped before taking the sample; yield; type of filtration; sampling method; date the sample was collected; and anion-cation balance.

Yucca Mountain, Nevada (fig. 1), is being investigated by the U.S. Geological Survey, in cooperation with the U.S. …

The Stratigraphy And Ichnology Of A Submarine Cave In The Exuma Cays, Bahamas, H. Allen Curran, Robert F. Dill

Geosciences: Faculty Publications

Reprinted from: Roger J. Bain (ed.), 1991, Proceedings of the Fifth Symposium on the Geology of the Bahamas: San Salvador, Bahamian Field Station.

Master Of Science Theses And Doctor Of Philosophy Dissertations, Dept. Of Geology, University Of Nebraska-Lincoln, R. R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Explanation Of Water-Level Hydrographs, P. B. Wigley, M. J. Ellis, G. V. Steele

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Groundwater-Level Changes In Nebraska, Predevelopment To Fall 1991, Conservation Survey Division

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

A Seismic Analysis Of Black Creek And Wabumun Salt Collapse Features, Western Canadian Sedimentary Basin, Neil Lennart Anderson, Robert James Sidford Brown

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

These salt remnants and their associated collapse features are often associated with structural or stratigraphic traps. As a result of the relationships between dissolution and hydrocarbon entrapment, the distribution (areal extent and thickness) of these salt remnants is of significant interest to the explorationist. Seismic information about the thickness and the extent of these salts should be used together with well log control to generate subsurface distribution maps. These maps will facilitate both the delineation of prospective structural and stratigraphic play fairways and the determination of the timing of salt dissolution. In addition, an appreciation of regional salt distribution will …

Differential Compaction Of Winnipegosis Reefs: A Seismic Perspective, Neil Lennart Anderson, Evan K. Franseen

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Winnipegosis Formation reefs in southern Saskatchewan are typically encased in the thick, apparently incompressible salts of the Prairie Evaporite. Illustrates the usefulness of seismic data to separate postdepositional compaction features from primary features to determine the primary morphology of a reef better and to determine the relative amounts of postdepositional compaction with the different reef environments.

Constraints On Unroofing Rates In The High Himalaya, Eastern Nepal, Mary S. Hubbard, L. H. Royden, K. V. Hodges

Geosciences Faculty Publications

Thermobarometric data for samples across the Main Central thrust zone in eastern Nepal show an inversion in temperature but not in pressure. These data have been interpreted to represent a portion of the paleogeotherm at the time of Main Central thrust deformation. A 40Ar/39Ar age on hornblende (closure temperature (Tc)=500±50°C) constrains the timing of this deformation to be ∼21±0.2 Ma. The 40Ar/39Ar ages of other minerals (muscovite, Tc=350°C, age (t)=12.0±0.2 Ma; K-feldspar, Tc=220°C, t=8.0±0.2 Ma) from the same location further constrain the cooling history of this region. Together the geochronologic and thermobarometric data yield an average unroofing rate of 1.2±0.6 …

Geologic Highway Cross Section: Kentucky Highway 80, Hazard To Prestonburg, Donald R. Chesnut Jr.

Map and Chart--KGS

Highway roadcuts along Kentucky Highway 80 from Hazard to Prestonsburg are scientifically significant exposures of the Pennsylvanian coal-bearing rocks of the Eastern Kentucky Coal Field, and provide an excellent educational opportunity. The coals exposed along this road are the most economically important of the coal field, and the roadcut exposures offer easy access and stratigraphic variety. They are ideal for high school, university, and professional geology field trips (Cobb and others, 1981). Several national and international field trips and many out-of-state university field trips have examined these exposures. In addition, studies in coal geology and petrography, paleontology, biostratigraphy, and elastic …

Mineralization And Hydrocarbon Emplacement In The Cambrian-Ordovician Mascot Dolomite Of The Knox Group In South-Central Kentucky, Warren H. Anderson

Report of Investigations--KGS

The Mascot Dolomite, the upper unit of the Cambrian-Ordovician Knox Group, is a major host for Mississippi Valley-type ore deposits and petroleum in south-central Kentucky. The Mascot was deposited on a broad, shallow platform that exhibited unusually uniform conditions of deposition, ranging from supratidal to shallow subtidal environments. The formation has a complex diagenetic history, including several stages of dolomitization, silicification, solution, and brecciation. Diagenesis and, to some extent, deposition were influenced by Early Ordovician tectonic activity. Tectonic activity influenced development of a regional unconformity during Middle Ordovician time. Evidence of this tectonic activity includes up to 300 feet of …

Radon Deposits In Nebraska, R. R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

A Detailed Gravity Study Over A Known Devonian Carbonate Buildup: The Shell Golden Reef, Northwestern North Dakota, Stephen M. Braun

Theses and Dissertations

A detailed gravity study was conducted over the Shell Golden reef in the northwestern North Dakota portion of the Williston Basin. The Shell Golden reef has been previously interpreted to be reefal facies within the Winnipegosis Formation (Devonian) located at a depth of about 2400 meters. Based only on information from wireline logs and core from two boreholes, the Shell Golden well #34X-34 has been previously interpreted as a pinnacle reef with 70 meters of relief and undetermined diameter. The basin regime of the Elk Point shelf created an environment that allowed the growth and development of the Shell Golden …

Erosion Of Fractured Banks, Lake Sakakawea, Western North Dakota, Mark C. Elliott

Theses and Dissertations

Shoreline erosion at Lake Sakakawea has exceeded originally predicted rates. This thesis is a continuation of a project, begun in 1983, to study erosion rates, causes, and prediction; the purpose has been to describe variations in fracture patterns in shoreline banks and assess their affects on erosion rates.

During the first phase of this project (1983-1986), average bank recession was rapid (l.Sm/yr) and factors related to wave action, including fetch, bank orientation, and beach composition, were most important. Since 1986, low lake levels have persisted and wave action has not been a factor; however banks continue to recede, but at …

Fracture-Enhanced Porosity And Permeability Trends In The Bakken Formation, Williston Basin, Western North Dakota, Wayne B. Freisatz

Theses and Dissertations

Fractures play a critical role in oil production from the Bakken Formation (Devonian and Mississippian) in the North Dakota portion of the Williston Basin. The Bakken Formation in the study area is known for its low matrix porosity and permeability, high organic content, thermal maturity, and relative lateral homogeneity. Core analysis has shown the effective porosity and permeability development within the Bakken Formation to be primarily related to fracturing.

In theory, lineaments mapped on the surface reflect the geometry of basement blocks and the zones of fracturing propagated upward from them. Fracturing in the Williston Basin is thought to have …

Hydrogeology Of Thrust Faults And Crystalline Thrust Sheets: Results Of Combined Field And Modeling Studies, Craig B. Forster, James P. Evans

Geosciences Faculty Publications

Field, laboratory, and modeling studies of faulted rock yield insight into the hydraulic character of thrust faults. Late‐stage faults comprise foliated and subparallel faults, with clay‐rich gouge and fracture zones, that yield interpenetrating layers of low‐permeability gouge and higher‐permeability damage zones. Laboratory testing suggests a permeability contrast of two orders of magnitude between gouge and damage zones. Layers of differing permeability lead to overall permeability anisotropy with maximum permeability within the plane of the fault and minimum permeability perpendicular to the fault plane. Numerical modeling of regional‐scale fluid flow and heat transport illustrates the impact of fault zone hydrogeology on …

Slickenside Petrography: Slip-Sense Indicators And Classification, Young-Joon Lee

Geology Theses and Dissertations

Petrographic study has been carried out on slickenside thin sections, to find out reliable microstructures for determining the slip-sense of faults, and to classify slickensides morphologically. Thin sections are made cut parallel to the striation and perpendicular to the slip plane. Many useful slip-sense indicators are found in thin section even though such indicators may be absent in hand specimens. They are (1) off-set or bending of once-continuous bodies such as veins, layers, grains or twin lamellae, (2) crystal fibers growing nearly parallel to the slip direction, (3) extensional fractures aligned oblique to the slip plane, (4) S-C geometries in …

Mineral Paragenesis Of The Granulite Facies In The Lake George Area, New York, Boknam Ree

Geology Theses and Dissertations

The Lake George Area belongs to the southeastern part of the Adirondack Highlands. The rocks of this area show variations in mineral assemblages which are caused by differences in bulk chemical composition. This makes it unsuccessful to use a subdivision of the granulite facies which is suggested by de Waard (1965).
The CFM diagram (Abbott, 1982) is used to show the relationship between composition and paragenesis of the Lake George Area. In this study, a different result has been found in the order of partitioning of Fe between coexisting minerals, namely, garnet>hornblende>biotite>orthopyroxene>clinopyroxene. The hornblende granitic gneiss …

Evaluation Of Computational Methods Of Paleostress Analysis Using Fault-Striation Data, Steven Henry Schimmrich

Geology Theses and Dissertations

Over the past 12 years, many different computational methods or variations of existing methods have been proposed for determining paleostress tensors from fault populations and their slip directions. These methods are all based upon well-known relationships between stress and shear and use iterative, non-linear mathematical algorithms which seek to minimize the angles between the calculated maximum shear stress direction and the observed movement directions on each fault plane in a population. The solution returned is the best-fit paleostress tensor for the population.
By taking the Coulomb failure criterion into account, several paleostress analysis programs have been able to use linear, …

Low-Silica And High-Calcium Stone In The Newman Limestone (Mississippian) On Pine Mountain, Harlan County, Southeastern Kentucky, Garland R. Dever Jr., Jack R. Moody, Thomas L. Robl, Lance S. Barron

Information Circular--KGS

The coal industry of Kentucky is an important market for limestone. Coal producers use limestone as rock dust for explosion abatement in underground coal mines and as a neutralizing agent in surface-mine reclamation and acid-drainage control. Crushed stone is also used for constructing and maintaining haulage roads.

In the Eastern Kentucky Coal Field, the coal-bearing rocks of Pennsylvanian age generally do not contain limestones that are thick enough to quarry or mine economically. But movement on the Pine Mountain overthrust fault has brought the Newman Limestone (Mississippian) to the surface along Pine Mountain in the southeastern part of the coal …

Paleontological Survey Of The Pennsylvanian Rocks Of The Eastern Kentucky Coal Field: Part 1, Invertebrates, Donald R. Chesnut Jr.

Information Circular--KGS

Morse (1931) conducted the last paleontological survey of the Eastern Kentucky Coal Field almost 60 years ago. Substantial new information generated by mapping, as well as sedimentological, stratigraphic, and paleontological studies, now justify a new paleontological survey of these rocks. This survey is a compilation of both the new and old information.

Lithologic analysis reveals at least 41 marine zones in the coal field. Paleontological analysis shows that a variety of faunal communities existed, and many of the marine zones contain abundant and diverse faunal assembleges. However, the biostratigraphic resolution of invertebrate fossils is apparently very poor compared to the …

Annual Installation Of Irrigation Wells In Nebraska Through 1990, Conservation Survey Division

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.