Yellowknife Geoscience Forum

The Northwest Territories Geological Survey (NTGS) has been undertaking a series of 1:10,000 and 1:15 000 scale mapping initiatives in greenstone belts of the Slave craton. The projects focus on areas of elevated resource potential surrounding Sunset Lake, Newbigging Lake, and Keskarrah Bay on Point Lake.  In collaboration with researchers and graduate students at Mount Royal University (Calgary) and the University of Saskatchewan (Saskatoon), a number of 1:2000 and 1:5000 scale detailed mapping transects have been completed.  Together these projects are aimed at understanding the early evolution of the Slave craton, particularly the tectonic setting of emplacement of volcanic rocks and related sedimentary rocks and their relationship(s) to basement granitoids, to improve knowledge of ore-forming processes and to better understand controls on base metal and precious metal endowment.

Ongoing work in the Sunset Lake area (110 km east-northeast of Yellowknife) has taken a multi-faceted approach to enhance the knowledge of the litho- and chemo-stratigraphy of the Beaulieu volcanic belt and the Sunrise volcanogenic massive sulfide (VMS) deposit that it hosts.  Bedrock mapping at 1:10,000 and 1:2000 scale and core logging has provided the details of the complex stratigraphy and geochemical signatures required for stratigraphic correlations within this volcanic belt, and has elucidated the VMS deposit model to help target future VMS mineral exploration in the Slave craton. 

A new bedrock mapping initiative in the Winter Lake greenstone belt at Newbigging Lake (250 km northeast of Yellowknife) is designed to evaluate the nature of physical and temporal relationships between the major groupings of rocks in the belt including: 1) basement granitoids, 2) ca. 3.1 to 3.3 Ga felsic to intermediate volcanic rocks of the Newbigging Formation and related intrusions, 3) rocks of the ca. 2.85 Ga Central Slave Basement Complex, 4) the bimodial volcanic rocks of the Snare and Providence formations (likely equivalent to the ca. 2.73–2.66 Ga Kam and Banting groups respectively) and syn-volcanic diorite to gabbro intrusions, 4) Burwash Formation equivalent turbidites, and 5) <2605 Ma polymictic conglomerates of the Sherpa Formation.  This initiative will establish additional absolute ages for rocks in and surrounding this greenstone belt, and the volcanic and sedimentary environments in which the rocks were emplaced, the diverse geochemical characteristics of these rocks, and their metallogenic history. 

In 2019, a 65 000 line-km high-resolution magnetic survey was flown covering parts of NTS map sheets 086H, 086A, and 076E, including the Point Lake greenstone belt and surrounding granitoid basement complex.  Ongoing bedrock investigations of the Point Lake greenstone belt at Keskarrah Bay (330 km northeast of Yellowknife) continued in 2019 with a 1:15,000 scale bedrock mapping project focused on the southwestern arm.  This distinct part of the greenstone belt consists of mafic to intermediate lavas, volcaniclastic rocks, and related intrusions.  While this part of the Point Lake greenstone belt contains surface exposures of VMS-type mineralization, it lacks known VMS mineralization on the scale of IZOK Lake, which is located to the north in Nunavut, within the same seemingly contiguous volcanic rocks.