Bernard Rolf Schnieders HBSc thesis abstract

Thesis Title: 
Geology and Structure of a Section of the Henik Group, Smiling Ghost Lake, District of Keewatin, NWT

The thesis area is located in the Keewatin District of the Northwest Territories on the east shore of Smiling Ghost Lake.  An approximate 1.2 km2 area of metamorphosed Archean volcanic and sedimentary rocks of the Henik Group was studied in detail.  The rocks vary in metamorphic grade from greenschist to epidote-amphibolite facies.  Pillowed and massive basic flows are the major lithology in the thesis area and form the upper and lower volcanic units.  Medium grained porphyritic rocks of andesitic composition occur as irregular shaped bodies throughout the sequence. 

Volcaniclastic rocks vary from tuffaceous to breccia textures and are both oligomict and polymict.  These rocks interlayer the basic flows in the central portion of the thesis area.  Macroscopic and microscopic examination of the volcaniclastic breccias combined with geochemical whole rock analyses indicates derivation from a multicompositional source area.  Therefore it is postulated that the Smiling Ghost Lake area is a section of the epiclastic rocks represent reworked units.  Gravity sliding and slumping in a subaqueous environment are suggested as possible methods of deposition, and were likely similar to a laharic type deposition present in the cone-complex facies.

Strike-slip faults caused by compressive forces are present throughout the thesis area and have developed well defined shear zones, jointing and minor folds.  Shearing and metamorphism cause variable amounts of deformation and foliation in the rocks, which have been subjected to several periods of deformation.

Sulphide mineralization is present in a fracture filled shear zone found in basic volcanic rocks.  Chalcopyrite, sphalerite, pyrite and iron oxides are found with deformed and foliated quartz-sericitic rocks.  Cataclastic textures in both the ore minerals and the fracture filling material indicate that deformation along the shear zone was intense.  Likely the fracture filling itself was sheared and brecciated by later movements along the fault.