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Full-Text Articles in Physical Sciences and Mathematics
The Application Of Biostratigraphy And Paleoecology At Southern Ocean Drill Sites To Resolve Early To Middle Miocene Paleoclimatic Events, Ryan Farmer
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
The diatom biostratigraphy and paleoceanography of Ocean Drilling Program (ODP) Site 744 on the Southern Kerguelen Plateau, southern Indian Ocean are documented for the early to middle Miocene to improve chronostratigraphic age control for the Southern Ocean and Antarctic region. Paleoenvironmental fluctuations in the Southern Ocean are inferred from changes in fossil diatom abundance, preservation, and assemblage composition. A robust, new age model for Holes 744A and 744B is constructed using Constrained Optimization (CONOP) model ages for diatom biostratigraphic datum levels and new magnetic polarity data, which enables assessment of a nearly continuous record of paleoenvironmental change from ~20.25 to …
Late Pleistocene Paleohydrography And Diatom Paleoecology Of The Central Basin Of Lake Malawi, Africa, Jeffery R. Stone, Karlyn S. Westover, Andrew S. Cohen
Late Pleistocene Paleohydrography And Diatom Paleoecology Of The Central Basin Of Lake Malawi, Africa, Jeffery R. Stone, Karlyn S. Westover, Andrew S. Cohen
Department of Earth and Atmospheric Sciences: Faculty Publications
Analysis of sedimentary diatom assemblages (10 to 144 ka) form the basis for a detailed reconstruction of the paleohydrography and diatom paleoecology of Lake Malawi. Lake-level fluctuations on the order of hundreds of meters were inferred from dramatic changes in the fossil and sedimentary archives. Many of the fossil diatom assemblages we observed have no analog in modern Lake Malawi. Cyclotelloid diatom species are a major component of fossil assemblages prior to 35 ka, but are not found in significant abundances in the modern diatom communities in Lake Malawi. Salinity- and alkalinity-tolerant plankton has not been reported in the modern …
A Regional-Scale Climate Reconstruction Of The Last 4000 Years From Lakes In The Nebraska Sand Hills, Usa, Jens Schmieder, Sherilyn C. Fritz, James B. Swinehart, Avery L. C. Shinneman, Alexander P. Wolfe, Gifford Miller, N. Daniels, K. C. Jacobs, Eric C. Grimm
A Regional-Scale Climate Reconstruction Of The Last 4000 Years From Lakes In The Nebraska Sand Hills, Usa, Jens Schmieder, Sherilyn C. Fritz, James B. Swinehart, Avery L. C. Shinneman, Alexander P. Wolfe, Gifford Miller, N. Daniels, K. C. Jacobs, Eric C. Grimm
Department of Earth and Atmospheric Sciences: Faculty Publications
High-resolution paleohydrological reconstructions were carried out in five shallow lakes in the Nebraska Sand Hills across an east–west transect in order to 1) determine whether long-term droughts of the past 4000 years were spatially and temporally coherent across the region, 2) distinguish local variation in climate or hydrology from regional patterns of change, and 3) compare the paleolimnological results with the existing dune-inferred drought records. Diatom- inferred lake-level was reconstructed for all sites and compared with other regional records. Alterations between high and low lake-levels were frequent during the past 4000 years, which suggests that shifts between dry and wet …