Physical Sciences and Mathematics Commons^™

Investigating The Impact Of Meteoric Diagenesis On The Geochemistry Of Carbonate Eolianites, Eleuthera And Water Cay, The Bahamas, Graham S. Bonnot

LSU Master's Theses

The geochemical signatures imparted in major, minor, and trace elements, combined with light isotopes, suggest promising applications regarding the stabilization of meteorically altered limestone eolianites. Previous high-resolution studies have indicated that elements associated with carbonate diagenesis such as Mg and Sr can be valuable proxies for salinity and aragonite dissolution, respectively. In addition to testing these proxies, the analyses of several temperature-, diagenetic-, bioactive-, and redox-sensitive elements were evaluated using laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) to identify additional indicators during carbonate diagenesis. Two geochemical drivers of U were identified; (1) aragonite dissolution similar to Sr and (2) oxidation …

Investigating Uranium Incorporation In Modern Carbonates By Sequential Extraction: Applied To The Permian - Triassic Boundary In Lung Cam, Vietnam, Christopher Michael Wray

LSU Master's Theses

The Uranium (U) isotopic system can be used to model the extent of global-scale ocean anoxia by utilizing the 238U/235U ratios as a paleo-redox indicator (δ238U). While recent studies have shown promise with the use of this novel proxy, variability is seen in modern carbonate sediment samples suggesting that more work is needed in order to understand elemental U uptake during early marine diagenesis. This thesis utilizes a sequential extraction methodology in order to understand the distribution of authigenic U within carbonate sediments.

This thesis consists of four parts, (1) an evaluation and modification of a sequential extraction methodology for …

Distribution Of Uranium In A Black Shale Across The Shelf Of The Late Pennsylvanian Midcontinent Sea, Maxwell A. Lindaman

LSU Master's Theses

Uranium paleoredox proxies such as enrichment factors and 238U/235U ratios can be used to reconstruct redox conditions in ancient water masses on local and global scales based on the differential behavior of uranium in oxic, suboxic, and anoxic environments. Many studies have focused on black shales due to their high levels of metal enrichment and association with climactic events. However, the influence of local effects on uranium accumulation is uncertain, particularly in ancient epeiric sea environments. This study consists of two parts: an evaluation of common sequential extraction methods for U analysis (particularly the Tessier-type sequential extraction) and the application …

Elucidating Marine Pore Water Exchange And Fresh Aquifer Sources In Estimates Of Submarine Groundwater Discharge To A Coastal Lagoon, Christopher Gerald Smith

LSU Doctoral Dissertations

Dynamic balances between fresh groundwater, saline groundwater, and surface water control the physics and chemistry of subterranean estuaries. Investigations were performed in a subterranean estuary on physical processes contributing to fresh groundwater and saline water mixing, vertical and lateral positioning of this mixing zone, and how this mixing affects spatial and temporal distributions of ^234,238U, ²²⁶Ra, and ²²²Rn. The subterranean estuary is located in an unconfined aquifer beneath Indian River Lagoon, Florida, USA, where I could examine redox responses to altered flow regimes. Continuous groundwater and surface water level measurements suggest a strong hydrologic connection between this …