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Earth Sciences

Theses/Dissertations

Productivity

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Full-Text Articles in Physical Sciences and Mathematics

Variation In C/P Ratios In Devonian-Mississippian Marine Shales: Testing The Productivity-Anoxia Feedback Model, Brian T. Scott Jan 2009

Variation In C/P Ratios In Devonian-Mississippian Marine Shales: Testing The Productivity-Anoxia Feedback Model, Brian T. Scott

University of Kentucky Master's Theses

Carbon/phosphorus ratios for late Devonian-early Mississippian marine black shales along a transect from the Illinois Basin, across the Cumberland Saddle, and into the Appalachian Basin were evaluated to assess the role of productivity in organic carbon accumulation. Phosphorus is a key limiting nutrient for biological productivity in marine environments and may be regenerated preferentially relative to organic carbon, the amount of regeneration possibly being related to bottom-water anoxia. A positive feed-back mechanism (more specifically, productivity-anoxia feedback or PAF) has been proposed between water-column anoxia, high benthic regeneration of phosphorus, and marine productivity. This regeneration of phosphorus under anoxic conditions and …

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Continuous Late Pleistocene Paleoclimate Record From The Southwest African Margin: A Multi-Proxy Approach, Julia Keegan Shackford May 2005

Continuous Late Pleistocene Paleoclimate Record From The Southwest African Margin: A Multi-Proxy Approach, Julia Keegan Shackford

Geosciences Theses

Late Pleistocene sediments recovered from ODP Leg 175, Site 1085 are used to generate a high-resolution (500 yr) record of continental climate change in Southern Africa. The location of Site 1085, the SW African continental slope, provides a continuous hemipelagic section with a significant terrigenous component. Terrigenous sediments are transported via fluvial and/or eolian transport mechanisms with MIS 1 being dominated by eolian transport. Analyses, including grain-size, color reflectance, biogenic sediment geochemistry (%CaCO3, %TOC, and C/N), bulk sediment geochemistry, and clay mineralogy, are used to identify continental climate conditions in southern Africa. Analyses indicate glacial/interglacial variation. Median grain-size peaks are …

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