Graduate Student Seminars

Please join us for two grad student seminars this Friday March 1 starting at 3:30 pm in rm 155 Geology:

3:30 pm

Mattea Cowell

Impact of gypsum addition on pore-water chemistry in fluid fine tailings

The consumption of water and high concentrations of salts in fluid fine tailings (FFT) are two concerns that the oil sand industry faces. Water used in the separation of bitumen from sand and through the upgrading process contributes to 3-6 wt% of tailings. To recycle the process water, gypsum [CaSO4·2H2O] is added to FFT in tailings ponds to aid in the settling of clay particles. However, the known effects of gypsum addition to FFT pore water is limited. A batch experiment was performed to examine the effects of water chemistry and gas production overtime using the addition of differing concentrations of gypsum to FFT. When gypsum addition increases, a decrease in pH and increase in gas production, alkalinity, and concentrations of calcium, sodium, and total sulfides is observed. The addition of gypsum and polyacrylamide to sodium-rich FFT followed by dewatering by centrifugation produces centrifuged fine tailings (CFT) which are used for terrestrial reclamation in oil sands. However, it is currently unknown how the annual freeze-thaw process in the Canadian prairies affects the quality and distribution of pore water. The increased concentration of salts may generate saline soils and limit growth of vegetation. A column experiment was performed to examine the potential changes in salt redistribution in CFT over three consecutive freeze-thaw cycles. Ongoing research will analyze the water chemistry from sections of the column and compare any changes between each freeze-thaw cycle.

4:00 pm

Nancy Normore

Petrography and Geochemistry of the Paleoproterozoic Boundary Intrusions and associated brecciation in the Flin Flon area, Trans-Hudson Orogen, Canada

The Boundary Intrusions (ca. 1842 Ma) are a set of dykes and sills making up a volumetrically minor component of the metamorphosed volcanic, intrusive and sedimentary rocks of the Paleoproterozoic Flin Flon - Glennie Complex. They intrude formations within the Flin Flon arc assemblage (ca. 1890 Ma) and the unconformably overlying clastic rocks of the Missi Group (ca. 1845 Ma). All these rocks have been metamorphosed to greenschist grade and deformed during the Trans-Hudson Orogen, which peaked at about 1810 Ma. Breccias are a distinctive characteristic of the Boundary Intrusions and are seen occurring in all compositional types, ranging from felsic to ultramafic, with the brecciation adding to their textural and geochemical complexity

The breccia fragments comprise volcanic rocks and earlier crystallized phases of the Boundary Intrusion suite and rare fragments of Missi sandstones. The presentation will provide textural and compositional information about the Boundary Intrusion matrix and fragments from three separate sites – Green Street, Louis Lake and Phantom Beach. There are properties of the breccias, such as fragment-matrix relationships, fragment and matrix similarities or differences, as well as the environment of emplacement, which can be used to make inferences on the processes operating during the formation of the intrusion breccias.