NWT RESEARCH DATABASE

Regions: North Slave Region

Objective(s): To investigate the long-term evolution of continental crust on the early Earth and the onset of plate tectonics.

Project Description: This licence has been issued for the scientific research application No. 5862. Use small (several kg) samples of ancient rocks and minerals from the Slave Craton to investigate the long-term evolution of continental crust on the early Earth and the onset of plate tectonics. Field Methods: In the field, we will employ standard, low-impact field observations and sampling of rocks exposed at the surface. At the outcrop, we will use small geologic hammers to collect a couple of kg of rock sample per location. At each site, we will make general non-destructive observations (e.g., orientation of the rocks, minerals present). We will also be collecting small (gallon bag-sized) samples of sediments in beaches and eskers surrounding the rock outcrops with the hope of discovering ancient minerals whose host rocks have long-since been eroded away. We will have a Bush Hawk float plane with us for the research. The plane will make out-and-back day trips and land on lakes after which we will hike to surrounding rocks for study and sample collection. Laboratory Methods: We will employ a variety of physical techniques to break rocks down into their constituent minerals the University of Alberta, Penn State, and the Smithsonian. These minerals (e.g., zircon, quartz, feldspar) will then be studied using a variety of imaging and geochemical techniques to unravel their chemical histories. At the Smithsonian, minerals will be imaged and identified using a JEOL 8530F field emission electron microprobe and a FEI Nova NanoSEM. Chemical and U-Pb dating and analyses will be performed using the PSUchron LA-ICPMS laboratory at Penn State. Combined, these methods will enable state-of-the-art science to investigate the ages of rocks and minerals and their compositions (e.g., redox, trace element chemistry). These techniques will help build a picture of the early Earth (e.g., crustal thickness, tectonic regime, atmospheric composition). This work is strictly for scientific research- there are no economic implications of our investigations. We have already been in contact with NT Geological Survey (NTGS) scientists and the Tlicho community about our research plans. We will keep the relevant stakeholders in the NTGS in the loop as data and publications progress. We will spend several years studying the rocks once back from the field. All data collected will be published in open-access journals and presented at international geoscience conferences, and will be sent to relevant parties in the NWT upon publication. Data will also be uploaded to the EarthChem geochemistry database for preservation and open access. Samples of granitic gneisses and sediments will be stored in the National Rock and Ore collection in the Smithsonian Institution. PI Ackerson is a Curator of this collection and, upon completion of the initial stages of research, these samples we be fully incorporated into the National Rock and Ore collection and made available to the international research community for research in perpetuity. The fieldwork for this study will be conducted from: July 08 - September 07, 2024