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Calcium Isotopes In The Saint Agatha Kettle Lake Deposits Of Southern Ontario, Emma-Dawn Ferguson
Calcium Isotopes In The Saint Agatha Kettle Lake Deposits Of Southern Ontario, Emma-Dawn Ferguson
Electronic Thesis and Dissertation Repository
The St. Agatha kettle lake deposits, ON, Canada, contain a thick section of endogenic marl and coeval shelly fauna. Marl accumulation occurred from ~13,500 to ~8,200 cal yrs BP. This study examines controls on marl and shell δ44/42Ca, element ratios (Mg, Fe, and Ba), δ18O, δ13C, and 87Sr/86Sr ratios of marl calcite, shell aragonite, groundwater, and bedrock as proxies for paleolacustrine conditions. Results for Interval A (532.0 to 475.0cm) indicates a cooler, wetter climate, lower primary lake productivity and higher lake levels. Interval B (475.0 to 345.0cm) marks the onset of …
Calcium Isotopes In Natural And Experimental Carbonated Silicate Melts, Matthew Maloney
Calcium Isotopes In Natural And Experimental Carbonated Silicate Melts, Matthew Maloney
Electronic Thesis and Dissertation Repository
The calcium stable isotopic compositions of mantle-sourced rocks and minerals were investigated to better understand the carbon cycle in the Earth’s mantle. Bulk carbonatites and kimberlites were analyzed to identify a geochemical signature of carbonatite magmatism, while inter-mineral fractionation was measured in co-existing Ca-bearing carbonate and silicate minerals. Bulk samples show a range of composition deviating from the bulk silicate Earth δ44/40Ca composition indicating signatures of magmatic processes or marine carbonate addition to source materials. Δ44/40Cacarbonate-silicate values range from -0.55‰ to +1.82‰ and positively correlate with Ca/Mg ratios in pyroxenes. A series of experiments designed …