James Farquharson HBSc thesis abstract

Thesis Title: 
A Microstructural Analysis of Goldstrike’s Plateau Property, Yukon

The Plateau Property in central-eastern Yukon hosts extensive high grade gold mineralization within the Tintina Gold Province.  The property lies roughly 130 kilometers east of Mayo, Yukon within the Selwyn Basin on the western edge of ancestral North America.  The purpose of this study is to identify the microstructural controls on gold mineralization at the Plateau Property.

The Goldstack and Gold Dome zones of the Goldstrike Resources’ Plateau Property shows microstructural evidence of brittle-ductile deformation.  Microstructures indicate moderate temperatures during ductile deformation throughout the two zones.  Feldspars with undulose extinction, serrated grain boundaries, and subgrains indicate ductile deformation accommodated by dislocation creep.  Deformed quartz stockwork veining is evidence of continuous brittle-ductile deformation.  Quartz veins filling fractures are evidence for brittle deformation.  Crosscutting relationships of older and younger quartz veins all exhibit evidence for dislocation creep.  Other microstructures include kink banding and deformation twinning in feldspars.  Relict devitrified pseudotachylyte in multiple areas of drill core is evidence for brittle deformation associated with seismicity and is also subsequently ductilely deformed.  Abundant evidence for brittle-ductile deformation microstructures is strongly associated with increased gold mineralization at this property.

The strong dependence of gold mineralization on brittle-ductile deformation at the Plateau Property in the Yukon, has been observed by others in multiple other gold occurrences elsewhere.  Pseudotachylyte might also be found at other gold properties associated with brittle-ductile deformation.  Pseudotachylyte is characteristic of the brittle-ductile transition and can be used as a macroscopic indicator when looking for these structurally controlled gold zones.