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Full-Text Articles in Earth Sciences
Diagenesis Of Lower Cretaceous Pelagic Carbonates, North Atlantic: Paleoceanographic Signals Obscured, Tracy D. Frank, Michael A. Arthur, Walter E. Dean
Diagenesis Of Lower Cretaceous Pelagic Carbonates, North Atlantic: Paleoceanographic Signals Obscured, Tracy D. Frank, Michael A. Arthur, Walter E. Dean
Department of Earth and Atmospheric Sciences: Faculty Publications
The stable isotope and minor element geochemistry of Neocomian (Lower Cretaceous) pelagic carbonates of the North Atlantic Basin (Deep Sea Drilling Project Sites 105, 367, 387, 391, and 603) was examined to develop a diagenetic model for pelagic limestones. In particular, we hoped to test the fidelity of whole-rock geochemical records as paleoceanographic indicators for pelagic deposits of pre-Aptian age, in which individual microfossils are not available for analysis. Data indicate that in addition to depth of burial, rhythmic variations in primary carbonate content have strongly controlled diagenetic patterns and associated geochemical signatures in these Neocomian sequences. Samples become increasingly …
Interannual Variations In Snowmelt Onset And Links To 500 Hpa Atmospheric Anomalies Over The Arctic, Sheldon D. Drobot, Mark R. Anderson
Interannual Variations In Snowmelt Onset And Links To 500 Hpa Atmospheric Anomalies Over The Arctic, Sheldon D. Drobot, Mark R. Anderson
Department of Earth and Atmospheric Sciences: Faculty Publications
Interannual variations in the melt onset of snow provide a mechanism to observe climatic fluctuations. Timing of initial ablation is associated with certain poorly defined overlying atmospheric conditions. This paper investigates the spatial and temporal patterns in melt onset dates and associated 500 hPa height anomalies over the Arctic region from 1982 to 1992. Melt onset dates are derived from Scanning Multichannel Microwave Radiometer (SMMR) and Special Sensor Microwave Imager (SSM/I) data, while 500 hPa height anomalies are computed from the National Centers for Environmental Protection (NCEP) reanalysis models. Results indicate significant interannual variations in the spatial pattern and timing …
Tectonic Forcings Of Maastrichtian Ocean-Climate Evolution, Tracy D. Frank, Michael A. Arthur
Tectonic Forcings Of Maastrichtian Ocean-Climate Evolution, Tracy D. Frank, Michael A. Arthur
Department of Earth and Atmospheric Sciences: Faculty Publications
A global compilation of deep-sea isotopic records suggests that Maastrichtian ocean-climate evolution was tectonically driven. During the early Maastrichtian the Atlantic intermediate-deep ocean was isolated from the Pacific, Indian, and Southern Oceans; deep water formed in the high-latitude North Atlantic and North Pacific. At the early/late Maastrichtian boundary a major reorganization of oceanic circulation patterns occurred, resulting in the development of a thermohaline circulation system similar to that of the modem oceans. A combination of isotopic and plate kinematic data suggests that this event was triggered by the final breaching of tectonic sills in the South Atlantic and the initiation …
Mountain Evolution And Environmental Changes Of Huangshan (Yellow Mountain), China, Pei-Hua Huang, Robert F. Diffendal Jr., Min-Qing Yang, Patricia E. Helland
Mountain Evolution And Environmental Changes Of Huangshan (Yellow Mountain), China, Pei-Hua Huang, Robert F. Diffendal Jr., Min-Qing Yang, Patricia E. Helland
Department of Earth and Atmospheric Sciences: Faculty Publications
Huangshan (Yellow Mountain) is located in southern part of the lower reaches of the Yangtze River. The highest Lotus Flower peak is 1,864 m above sea level. Formative ages of the Huangshan and its granite, process of mountain geomorphic evolution from the Eocene to Quaternary, environmental changes of Quaternary, formative origin of beautiful peaks and fascinating rocks were studied and the questionable “Pleistocene glaciation” was also discussed in this paper.
Evaluation Of Stream Depletion Considering Finite Stream Width, Shallow Penetration, And Properties Of Streambed Sediments, Vitaly A. Zlotnik, Huihua Huang, James J. Butler Jr.
Evaluation Of Stream Depletion Considering Finite Stream Width, Shallow Penetration, And Properties Of Streambed Sediments, Vitaly A. Zlotnik, Huihua Huang, James J. Butler Jr.
Department of Earth and Atmospheric Sciences: Faculty Publications
Commonly used methods for estimation of pumping-induced stream depletion are based on a series of idealistic assumptions about the stream-aquifer interface. In many cases, however, these assumptions are not consistent with field conditions. In order to obtain stream-depletion estimates that are based on assumptions more appropriate for conditions often faced in the field, a new analytical model is proposed. This model, which incorporates the effects of finite stream width, shallow stream penetration, and a low permeability streambed, is based on the Dupuit assumptions and a steady-state representation of flow across the streambed. A general solution for stream depletion is developed …
Lethal Sandslides From Eolian Dunes, David B. Loope, Joseph A. Mason, Lowell Dingus
Lethal Sandslides From Eolian Dunes, David B. Loope, Joseph A. Mason, Lowell Dingus
Department of Earth and Atmospheric Sciences: Faculty Publications
Fossil vertebrates entombed within the Upper Cretaceous Djadokhta Formation of southern Mongolia bear testimony to a heretofore unknown geologic phenomenon: mass wasting of eolian dunes during heavy rainstorms. Evaporation of shallow-penetrating rainwater led to progressive calcite accumulation in a thin layer of sand about 0.5 m below the surface of dune lee slopes. During rare heavy rainstorms, a perched water table developed at the top of calcitic zones. Positive pore water pressure led to translational slides and fast-moving sediment gravity flows that overwhelmed animals on the lee slopes of large dunes and in interdune areas.