NWT RESEARCH DATABASE

Regions: North Slave Region

Tags: physical sciences, paleogeology, aurora borealis, electromagnetic survey, earth science

Objective(s): The objective of the research is to age the regional scale electrical conductivity structure of the crust and mantle beneath the Slave craton to determine (a) the lateral variation of the cratonic mantle root, (b) whether the conductivity is anisotropic, (c) the presence of a conducting lower crust, and (d) the presence of an asthenospheric zone in the mantle. Answers to these questions will enable us to address the questions of whether (a) the root is Archean in age or is more likely caused by Proterozoic processes, (b) how the root grew in time, and (c) whether the root is original, or has been modified with time. The geometry of the base of the root may also guide exploration activities for diamondiferous kimberlites.

Project Description: Using passive, electromagnetic instrumentation designed and developed for use on the ocean bottom, we will make measurements of the time-varying electromagnet fields caused by the northern lights at 10 lakes, 3 in Nunavut, in the Slave craton. At each lake an instrument will be deployed from a Turbo Beaver float plane and the instrument will drop to the bottom of the lake and start to make recordings. One year later we will return and send a signal to the instrument which will cause it to rise to the surface. Nothing will remain on the lake bottom. The instrument is totally passive and non-toxic. We intend to deploy the instruments in the deeper parts of the lakes (>100 feet if possible) so fishing will not be affected. The only disturbance to the environment will be caused by the float plane landing and taking off. The instruments each contain a magnetometer, to measure the time variations of the Earth's natural magnetic field, and an electrometer, to measure the time variations of the Earth's natural electric field.