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Articles 1 - 5 of 5
Full-Text Articles in Physical Sciences and Mathematics
Marine Diatom Assemblage Variation Across Pleistocene Glacial-Interglacial Transitions And Neogene Diatom Biostratigraphy Of Site C9001, Nw Pacific Ocean, Marcella K. Purkey
Marine Diatom Assemblage Variation Across Pleistocene Glacial-Interglacial Transitions And Neogene Diatom Biostratigraphy Of Site C9001, Nw Pacific Ocean, Marcella K. Purkey
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
In 2006, D/V-Chikyu cruise CK06-06 drilled Hole C9001C at Site C9001 in the Northwest Pacific Ocean, 80 km east of the Shimokita Peninsula, Japan. An existing chronostratigraphic framework provides a continuous glacial-interglacial (GI) climate record from which a diatom record of paleoenvironmental changes was developed across several GI cycles. Species counts, diatom temperature values, calculated sea-surface temperatures (SST) and factor analysis were produced for each sample and calibrated to prior diatom studies in this region. These features were used to characterize and compare interglacial maxima of Marine Isotope Stages (MIS) 1, 5e, 9 and 11 and transitions from the preceding …
Hydrochemical Investigation Of A Transient Parafluvial Zone Under Drought Conditions, Platte River, Nebraska, Audrey R. Boerner
Hydrochemical Investigation Of A Transient Parafluvial Zone Under Drought Conditions, Platte River, Nebraska, Audrey R. Boerner
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
Shallow groundwater (0.5 m -1.2 m deep) beneath a vegetated and non-vegetated fluvial island was observed in the lower Platte River, Nebraska, USA during exceptional summer drought. Over the course of three months, sub-hourly measurements of hydraulic head, and weekly measurements of redox indicators, δ2H, δ18O, and dissolved gases were analyzed together with nitrogen and carbon species from an array of shallow piezometers in the river bed and islands. These data were compared with the same parameters collected from a 15 m-deep riparian borehole. Vertical hydraulic gradients in the island piezometers indicated the vertical component to …
Geometry And Evolution Of Fold Structures Within The High Folded Zone: Zagros Fold-Thrust Belt, Kurdistan Region-Iraq, Mjahid Zebari
Geometry And Evolution Of Fold Structures Within The High Folded Zone: Zagros Fold-Thrust Belt, Kurdistan Region-Iraq, Mjahid Zebari
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
Understanding the deformation style within the Zagros Fold-Thrust Belt is crucial for understanding the convergence between the colliding Arabian and Eurasian plates and nature of structures that trap hydrocarbons within the belt. The Zagros Fold-Thrust Belt has propagated ~250 km southwest-ward in Northern Iraq. In this study, deformation style of a number of fault-related folds within a part of the belt has been considered. The research intends to understand the geometry and formation mechanisms of these folds, via constructing models for the deformation geometry of folds and associated thrusts at depth using field data and seismic lines and detecting their …
Oil-Source Rock Correlation In The Late Paleozoic, Denver Basin, Nebraska -The Search For A Negative Δ¹³C Anomaly In Pennsylvanian-Permian Cyclothems, John P. Still
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
Late Paleozoic sedimentation in the Denver basin occurred in two environmentally distinct depocenters. The northern-most Alliance Basin has been interpreted to have a restricted character: anhydrite-bearing mudstones are present in cyclothems comprising wackestone, packstone and mudstone. The source of petroleum produced from these intervals is considered to be organic-rich units within these cyclothems. Oil recovered from late Paleozoic reservoirs has δ13C values that range from -30.8‰ to -28.8‰: values that are lower than those reported previously for prospective source rocks from this interval. Cores from seven wells that penetrate upper Pennsylvanian to lower Permian rocks have been chosen for analysis. …
Paleoecology Of Nebraska’S Ungulates During The Eocene-Oligocene Climate Transition, Grant S. Boardman
Paleoecology Of Nebraska’S Ungulates During The Eocene-Oligocene Climate Transition, Grant S. Boardman
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
The White River Group (WRG) preserves the Eocene-Oligocene climate transition (EOCT), an interval of global cooling and drying during the onset of Antarctic glaciation. In the Great Plains, a shift from forested conditions to drier woodland-savanna biomes is hypothesized to have occurred at this time. I test this hypothesis through the analyses of several paleoenvironmental proxies on the teeth of 12 WRG ungulate species: stable carbon and oxygen isotopes from tooth enamel, and mesowear and microwear texture. The EOCT shift toward more open habitats and lower vegetation density under drying climates should have resulted in an increase in mean carbon …