Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 3 of 3
Full-Text Articles in Entire DC Network
Impact Of Calcium Carbonate Reactant Size And Mineralogy On Dolomite Stoichiometry, Katharine G. Rose
Impact Of Calcium Carbonate Reactant Size And Mineralogy On Dolomite Stoichiometry, Katharine G. Rose
Masters Theses
Dolomite is a common, diagenetic, Mg-Ca carbonate mineral. Dolomitization occurs by a dissolution-precipitation reaction between a CaCO3 precursor (calcite or aragonite) and Mg bearing fluids. The amount of Mg in dolomite, referred to as dolomite stoichiometry (mol% MgCO3), varies in natural dolomites (38-50 mol% MgCO3). Laboratory experiments have shown that dolomite stoichiometry is dependent on physiochemical factors of the diagenetic fluids (i.e., temperature, salinity, and Mg/Ca). The impact of the CaCO3 precursor on stoichiometry, however, has not been studied directly. This study tests how the CaCO3 precursor size (sieve size) and mineralogy (calcite …
Anomalous Thermal Indicators From Authigenic Minerals In Upper Paleozoic Strata Of The Michigan Basin, Kyle Cox
Masters Theses
Indications of anomalous paleo-temperatures exist in strata of the Michigan basin, USA. The thermal history of the basin was investigated through identification and analysis of authigenic components in two Upper Paleozoic strata, the Devonian Dundee Formation and Mississippian Marshall Sandstone. Formation conditions for diagenetic phases in both units were estimated through a variety of means and compared to conditions expected for a simple burial model. Authigenic clays identified in the Marshall via X-ray diffraction are expected to have formed at temperatures above what would have been produced by burial alone. Stable isotope and fluid inclusion analysis indicate the same for …
Calcitized Evaporites In The Precambrian: Deposition And Diagenesis In A Low Sulfate Ocean, Ashley René Manning Berg
Calcitized Evaporites In The Precambrian: Deposition And Diagenesis In A Low Sulfate Ocean, Ashley René Manning Berg
Masters Theses
One of the most profound byproducts of the Great Oxidation Event (GOE) was the onset of oxidative weathering on land and the riverine delivery of sulfate to marine systems. The marine sulfur system therefore plays a critical role in reconstructing the oxygenation of the early Earth. Although the exact nature of marine oxygenation in aftermath of GOE remains uncertain, examination and modeling of marine sulfate suggest that sulfate concentrations remained below 2 millimolar (mM) until at least the middle Mesoproterozoic, and may have only reached about 10 mM in the latest Neoproterozoic. Such a low concentration of marine sulfate had …