NWT RESEARCH DATABASE

Tags: bedrock, lithology, volcanic rocks

Objective(s): To geochemically compare three Archean volcanic belts in the Slave craton by detailed mapping, select transects, and comprehensive sampling.

Project Description: Through detailed mapping, select transects, and comprehensive sampling, a geochemical comparison of three Archean volcanic belts in the Slave craton (Northwest Territories) will help advance the knowledge of stratigraphy, and magmatic evolution within each belt. Detailed Mapping: traversing (walking) over bedrock outcrops, examining lithology’s, notes and picture taking, and sample collecting. To aid in this, topographical map overlays, and portable GPS point analysis software (ArcMap and Arc GIS) will be used to create digital maps of the project areas at 1:7500 and 1:24000 scales, where applicable. Transect: Using known lithological stratigraphy (identified through detailed mapping), measurements of lithological thickness can be made. This will be done by detailed note taking, measuring of rock thickness, and sample collection. Sampling Method: Collecting samples of the bedrock; with a standard rock hammer, samples size approximately 0.5kg for analytical procedures at Carleton University. Analytical Procedures: Petrographic thin sections will be made of all samples at Carleton University using rock saws and polishing techniques; and interpreted using petrographic microscopes. A chosen sample set will be selected based on petrographic and lithological criteria for further geochemical analysis. These selected samples will be made into geochemical rock powders at Carleton University using a Chipmunk Rock Crusher and Agate Ring-mill. These Rock powders will then be sent to ALS Minerals, Vancouver, for bulk rock and trace element analysis, using their Inductively Coupled Plasma – mass spectroscopy (ICP-MS), and Inductively Coupled Plasma – Atomic Emission Spectroscopy (ICP-AES). Furthermore, a smaller sample set will be analyzed at Carleton University’s Isotope Geochemistry & Geochronology Research Center (IGGRC), using their ThermoFinnigan Triton TI Thermal Ionization Mass Spectrometer, to collect a Neodymium (Nd) isotope data set. Data Interpretation: Utilizing select software packages (e.g. Excel, IgPet, GCDkit, etc.), the above mentioned geochemical data sets will be scrutinize and interpreted based on varying geochemical criteria. These data sets will also be compared to published data sets for rocks from elsewhere in the Archean Slave craton. This will aid in the understanding and knowledge of rock chemistry, magma composition, magmatic evolution, and crystallization histories for each lithological unit, as well as for each of volcanic belts (see project areas). Thorough the course of the project, involvement will be extended thorough local expediting firms and aircraft companies where applicable. Final results will be published in an MSc thesis, summarized in an Open Report through the Northwest Territories Geoscience Office, as well as expressed at the 2014 Yellowknife Goescience Fourm. The fieldwork for this study will be conducted from July 17, 2014 to August 31, 2014.