Cross Lake Project (1983-86)
Geologist P.G. Lenton
Year 83
STATION 5071
EASTING 572509
NORTHING 6041718
ZONE 14
DATUM NAD83
Date of mapping 06/26/1983
STRUCTURAL DATA
Structure type | Strike | Dip | Separation |
---|---|---|---|
schistosity | 71 | 64 | |
fault | 309 | 68 |
-several 1 to 3 cm minor mylonites
PHOTOS
2 or 3 photos of offset by youngest mylonite
2 photos of brecciation of older cataclasis
1 photo of refraction of younger mylonite along old slip plane (younger is fine fracture going left to right)
PETROLOGIC DATA
Rock Number: 1
-light white and pink layered gneiss complexly layered with pegmatite/aplite of more that one generation
Rock Number: 2
-grey-white subgneissic augen tonalite/granodiorite
- intrudes(?) the old tonalite/pegmatite complex and is now rafted in it because of cataclasis
-Could be cataclastic equivalent of the younger porphyritic grey granodiorite that is a major component of the two component migmatites.
Type | Mineral | Min. Size | Max. Size | Abundance (%) | Unit |
---|---|---|---|---|---|
mafic mineral | biotite | 0.0 | 0.0 | 12.0 | % |
Rock Number: 3
-large inclusions up to 4-5 m across of mafic black and green weathering gneiss
-layering discontinuous with numerous diopside-plagiclase clots and stringers; almost certain to be a pillowed or brecciated flow.
-several thin 1 m layers are almost featureless black amphibolite that may be massive flows
Type | Mineral | Min. Size | Max. Size | Abundance (%) | Unit |
---|---|---|---|---|---|
raft size in metres | 4.0 | 5.0 |
Mineral | Abundance (%) |
---|
hornblende |
diopside |
plagioclase |
Rock Number: 4
-younger pegmatites that post date above units but are extensivly sheared and brecciated
-contain graphic microcline, plagioclase, biotite, garnet and traces of silver metallic mineral; probable specular hematite
-Pegmatite is associated with black-speckled aplite (sample)
Mineral | Abundance (%) |
---|
biotite |
garnet |
specular hematite |
PHOTOS
Young dextral mylonitesbrecciating multicomponent gneisses
Detail of consistent dextral offsets by late NW trending mylonite. Note the pseudotachylite development near the scale card.
Sinistral folding in old cataclasis in the augen tonalite.
Old shearing in augen gneiss with sinistral form. Quartz veins in shear are boudinaged and rolled.
Refraction of younger mylonites (309°) along old slip plane of the main deformation fabric (071°).
Manitoba Geological Survey, 2017