Graduate Student Seminars

Please join us for two graduate student seminars this Thursday (note different weekday due to Good Friday) April 18 at 3:30 pm in rm 155 Geology:

3:30 pm

Aidan Mowat, MSc candidate

Hydrogeochemistry of Devonian brines in the Williston Basin, Canada

Freshwater influx into the Western Canada Sedimentary Basin (WCSB), synchronous to regional flow reversal, has produced complex geochemical signatures along the northeast flank of the basin. Infiltration to aquifers has generated distinct endmember sources and evidence of fluid mixing. The WCSB ranges from the Canadian Yukon and Northwest Territories, through Alberta and southern Saskatchewan, into southwest Manitoba, and south into the states of North Dakota, Montana, and South Dakota. The WCSB is further divided into the Alberta Subbasin and Saskatchewan Subbasin, where the latter is concurrently known as the Williston Basin. In the Williston Basin, a series of aquifers in Mid to Upper Devonian strata produce an open aquifer system from Montana and South Dakota, U.S.A, to Manitoba, Canada. In this study, we used aqueous and isotopic (δ18O, δ2H, 87Sr/86Sr, δ37Cl, δ81Br) signatures of Devonian formation fluids to examine the potential sources and evolutionary history of fluids within the Williston Basin. We focus on the Devonian Prairie Evaporite formation and overlying strata including the Dawson Bay, Souris River, Duperow, and Birdbear formations. Two endmembers are interpreted from the geochemical signatures: (1) evaporative seawater and (2) a freshwater, meteoric component. The former endmember is derived from remnant evaporated seawater brine, while the latter is a result of Pleistocene glacial meltwater intruding into Devonian aquifers along the north-east margin of the basin. We report aqueous and isotope relationships to characterize these endmembers and improve our understanding of fluid transport in the basin.

4:00 pm

Yu Han, MSc Candidate

Investigation on an airborne magnetic and Helitem survey on Flin Flon area

The helicopter-borne time domain electromagnetic system HELITEM is a new generation system which was designed and operated by Fugro Airborne Surveys. It has much larger peak current as well as peak dipole moment and later first gate compared with other airborne time domain EM technologies such as SkyTEM, VTEM and AeroTEM etc. BFR Copper & Gold Inc. has made available a large HELITEM and magnetic survey of a volcanogenic massive sulfide (VMS) project in the Flin Flon area to be the data source of this study.

The induction of coil coupling over static geomagnetic field is firstly studied to determine if that would corrupt EM data especially late gate signals. VMS targets are expected to be both conductive and magnetic. Therefore, coincident magnetic and conductive anomalies are searched to indicate target areas. Subsequently, forward and inversion plate models are created using modeling software Maxwell which was developed by ElectroMagnetic Imaging Technology (EMIT). Radial Spectrum method and tilt derivative method are applied for depth estimation using magnetic data and the results were compared with inversion models to find consistency and further determine whether the potential conductors are worth of interest. Plate modeling on some of the more attractive targets is attempted to refine their depth, depth extent, size, shape and conductivity.