Sedimentology Commons^™

Speleothems As Proxy For The Carbon Isotope Composition Of Atmospheric Co2, M. Baskaran, R. V. Krishnamurthy

Environmental Science and Geology Faculty Research Publications

We have measured the stable isotope ratios of carbon in a suite of recent cave deposits (<200 >years) from the San Saba County, Texas, USA. The methodology for dating these deposits using excess ²¹⁰Pb was recently established [Baskaran and Iliffe, 1993]. The carbon isotope ratios of these samples, spanning the time period ∼1800–1990 AD, reflect the carbon isotope ratio of atmospheric CO₂ for the same period. The pathways by which the δ¹³C of atmospheric CO₂ is imprinted on these speleothems can be explained using a model developed by Cerling (1984). The results suggest that the …

Probable Glacial Climatic Conditions In Source Areas During Deposition Of Parts Of The Ash Hollow Formation, Ogallala Group (Late Tertiary), Of Western Nebraska, Patricia E. Helland, Robert F. Diffendal Jr.

Robert F. Diffendal, Jr., Publications

Evidence of the climatic conditions in the mountain sediment source areas for the late Tertiary Ash Hollow Formation of the Ogallala Group in western Nebraska has been sought in an SEM (scanning electron microscope) study of surface features on detrital quartz grains from these deposits. The following lines of indirect evidence raised the possibility of glacial conditions: uplift of up to 3500 m in the source areas, paleohydrologic parameters indicative of a transport system analogous to the modern North Saskatchewan River, and possible cold climate surface features on cobbles from the deposits. SEM analysis shows that five of the nine …

Geology, Geologic Time And Nebraska, Marvin P. Carlson

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Acoustic Properties Of Fine‐Grained Sediments From Emerald Basin: Toward An Inversion For Physical Properties Using The Biot–Stoll Model, Robert C. Courtney, Larry A. Mayer

Affiliate Scholarship

Acoustic data from two long cores, comprising marine clays and silts taken from Emerald Basin off Nova Scotia, are presented. High‐resolution measurements of compressional wavevelocity,attenuation, and power law exponent are made using ultrasonic frequencies between 100 to 1000 kHz. The observed values of the frequency dependence of attenuation suggest that a nonconstant Q mechanism is needed to explain these data, and Biot–Stoll theory is used to model the experimental results. An inversion scheme is used to constrain physical parameters in the Biot–Stoll dispersion relation. The inversion shows that there is a restricted range of permeability and grain size. By assigning …

Information And Regulations Pertaining To Industrial Minerals In Nebraska, Raymond R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Age Determination Of Recent Cave Deposits Using Excess 210Pb - A New Technique, M. Baskaran, Thomas M. Iliffe

Environmental Science and Geology Faculty Research Publications

Cave deposits have been widely used as proxy recorders in deciphering palaeoclimate during the last glacial/interglacial maxima (∼ 120 ka) [Harmon et al., 1975; Atkinson et al., 1978; Goede and Harmon, 1983; Ayliffe and Veeh, 1989]. Palaeoclimatic studies of cave deposits for the past 1–1000 yr time scale require a precise dating technique, that until now has been lacking. Due to the multiple sources of carbon in speleothems, ¹⁴C dates obtained for recently deposited calcite are highly variable and thus, ¹⁴C dating techniques are not suitable to obtain speleothem ages for the past 1–1000 years.

Here, we show …

Paleobathymetric Interpretation Of Pleistocene Sediments In The South Padre Island Area, Northwestern Gulf Of Mexico, Using Benthic Foraminiferal Morphology, Karen Ianthe Kruebbe-Belwood

OES Theses and Dissertations

This study tested the validity of using intraspecific variation in benthic foraminifera as a means for determining Pleistocene paleobathymetry. Canonical variate analysis was used as a means for determining visually undetectable but statistically significant differences in the morphology of selected species. Two species, Cassidulina subglobosa and Uvigerina peregrina, were collected from Pleistocene well cuttings from the northwest Gulf of Mexico. The canonical analysis involved comparing the intraspecific variation of these Pleistocene species to their counterparts occurring in the modern Gulf of Mexico, where intraspecific variation was previously analyzed and found to be sufficient to allow detection of bathymetric differences …

Flat Water: A History Of Nebraska And Its Water, Robert D. Kuzelka, Charles A. Flowerday, Robert N. Manley, Bradley C. Rundquist, Sally J. Herrin

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Calculation Of Acoustic Parameters By A Filter-Correlation Method, Robert C. Courtney, Larry A. Mayer

Affiliate Scholarship

This paper presents the filter correlation method, a technique for extracting consistent and accurate estimates of attenuation parameters from acoustic waveform data. The method minimizes problems associated with short time windows and multipath secondary arrivals. The method comprises two stages: a causal passband filter stage followed by a cross-correlation step. The results of the filter-correlation estimator are compared to those of the spectral difference approach for short time series with and without a secondary multipath arrival. Preliminary analyses of acoustic data collected on cored marine silts and clays show the attenuation properties of these materials cannot be described by a …

The Origin And Evolution Of The Southern Snake Range Decollement, East Central Nevada, Allen J. Mcgrew

Department of Earth, Environment and Sustainability Faculty Publications

Regional and local stratigraphic, metamorphic, and structural constraints permit reconstruction of the southern Snake Range extensional deformational system in east central Nevada. The dominant structure of the range, the southern Snake Range décollement (SSRD), operated during Oligocene and Miocene extensional deformation to exhume a footwall of multiply deformed metasedimentary and plutonic rocks. Intrusion of three plutons (∼160 Ma, 79.1 ± 0.5 Ma, and 36 ± 1 Ma, respectively) and development of two cleavages preceded the onset of extensional deformation. Plastic deformation of lower plate metasedimentary rocks accompanied the early phases of regional extension and produced bedding-parallel grain shape foliations and …

Variations Of Porosity In Calcareous Sediments From The Ontong Java Plateau, Frank Bassinot, Janice C. Marsters, Larry A. Mayer, Roy H. Wilkens

Affiliate Scholarship

Based on index properties measurements made on board the JOIDES Resolution, we studied porosity changes with depth in the fairly homogeneous deep-sea calcareous sediments cored during Ocean Drilling Program Leg 130 on the Ontong Java Plateau. Using Leg 130 data, we present evidence that the rate of porosity decrease with burial in calcareous oozes and chalks is related to the depth of deposition and thus probably depends on the "conditioning" of calcareous sediments by winnowing or dissolution processes during the time of deposition. The ooze-to-chalk transition is not clearly reflected in porosity profiles. In the ooze-chalk sections studied (the upper …

Uranium Deposits In Nebraska, R. R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Geology Of Arbor Day Farm Nebraska City, Nebraska, R. R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Correlation Of The Tioga Bentonites Using Rhyolitic Melt Inclusions Found In Quartz Phenocrysts As Geochemical Fingerprints, John W. Waechter

Geology Theses and Dissertations

The Tioga bentonites were first noted by Fettke in 1931 from well cuttings in the Tioga gas fields of Tioga County, Pennsylvania. They have been used by many investigators (Oliver, 1954, 1956; Dennison, 1963; Dennison and Textoris, 1967, 1978; Epstein, 1986; Smith and Way, 1983; Way et al., 1986) as a time-plane to correlate stratigraphic units from eastern Pennsylvania to Illinois and from southern Ontario to Virginia. The Tioga bentonites are recognized as seven major volcanic ash layers labeled Tioga-A - Tioga-G as well as several minor layers labeled Tioga-A1 - Tioga-A3 (Way et al., 1986). They occur within the …

Resource News-March/April 1993

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Nebraska Mineral Operations Review, 1992, R. R. Burchett, Duane A. Eversoll

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Cedar County Test Hole Logs, Raymond R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Cuming County Test Hole Logs, Raymond R. Burchett, Frank A. Smith

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Geology And Mineral Resources Of Boone, Greeley, Nance, And Wheeler Counties, Nebraska, Raymond R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Resource Notes-Academic Year 1992-93

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Resource News-July/August 1993

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Niobrara River Basin Geological References, Including Parts Of South Dakota Both In And Outside Of The Basin, Robert F. Diffendal Jr.

Conservation and Survey Division: Faculty and Staff Publications

Includes Niobrara River Basin geological references, including parts of South Dakota both in and outside of the basin.