Volcanic and tectonic history of mafic volcanic rocks in the Winter Lake greenstone belt, Slave craton, Northwest Territories
Date
2024-06-17
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0000-0002-7053-2817
Type
Thesis
Degree Level
Masters
Abstract
The Archean Winter Lake greenstone belt (WLB) is located in the western part of the Slave craton, ~250 km north-northeast of Yellowknife, Northwest Territories, Canada. Volcanic rocks of the WLB comprise calc-alkaline and tholeiitic basalts with komatiitic flows and associated volcaniclastic rocks contained in the ca. 2.7-2.6 Ga Snare and Credit formations, as well as felsic to intermediate volcanic rocks of the older Newbigging Formation. Archean volcanic sequences of the Slave craton in the Northwest Territories are highly prospective for base metal mineralization, as several are known to host volcanogenic massive sulfide (VMS) deposits. This MSc research elucidates the depositional and tectonic history of volcanic rocks that host massive sulfide mineralization in the WLB. Bedrock mapping (1: 2000 scale) of the mafic volcanic rocks of the WLB for this study took place in four different locations: 1) the south end of Sherpa Lake, 2) the south end of Big Bear Lake, and 3) at the 152 massive sulfide showing 20 km south of Big Bear Lake, and 4) the south end of Newbigging Lake. Lithofacies observed in the eastern WLB at Sherpa and Newbigging lakes include rhyolite domes with autoclastic breccias and highly sheared pillow basalts and mafic volcaniclastic rocks, though both areas are dominated by gabbroic intrusions. In the western WLB, lithofacies observed south of Big Bear Lake include massive and pillowed tholeiitic basalt flows with syn-volcanic mafic dykes and sills, thin komatiitic flows, ultramafic intrusions, and thick ash and lapilli tuff beds locally interbedded with calcareous sedimentary layers. Previous structural interpretations of the WLB have suggested a broadly synclinal architecture, but the proposed east and west limbs are difficult to correlate in terms of lithofacies. Trace element geochemistry of these units is consistent with a plume initiated evolving rift on a continental margin.
Description
Keywords
Slave Craton, Geochemistry
Citation
Degree
Master of Science (M.Sc.)
Department
Geological Sciences
Program
Geology