Cross Lake Project (1983-86)


Geologist    P.G. Lenton     Year    83     STATION    5052
EASTING   571834     NORTHING   6040050     ZONE   14     DATUM   NAD83
Date of mapping    06/23/1983

STRUCTURAL DATA

Planar Structures:
Structure type Strike Dip Separation
cataclastic foliation 41 61
gneissosity 41 61

minor mylonite seams in the foliation plane

PETROLOGIC DATA

Rock Number: 1

Rock Type: tonalite
Descriptors:
light grey
grey
old phase

Field Description:

- equal amounts of tonalite and various late grey granodiorite phases.
-These include a fine to medium grained grey granodiorite that shows good intrusive realtionship into the tonalite gneiss; the normal porphyritic granodiorite and a coarsely porphyritic granodiorite.

-minor mylonite seams are common in the foliation plane

Rock Number: 2

Rock Type: granodiorite
Descriptors:
dark grey
black
fine to medium grained

Field Description:

-young intrusive with sharp imtrusive contacts into old tonalite and including or dyking into the other granodiorite units

Textural Features
Type Mineral Min. Size Max. Size Abundance (%) Unit
mafic mineral biotite 0.0 0.0 mm

Rock Number: 3

Rock Type: porphyritic granodiorite
Descriptors:
grey
dark grey
porphyritic
massive

Field Description:

older of the 2 dominant late granodiorite to tonalite intrusives

Textural Features
Type Mineral Min. Size Max. Size Abundance (%) Unit
phenocryst plagioclase 2.0 5.0 10.0 mm
mafic mineral biotite 0.0 0.0

Rock Number: 4

Rock Type: granodiorite
Descriptors:
light grey
dark grey
megacrystic

Field Description:

not a common phase - appears to be approximately the same age as rock 3, may be related.

Textural Features
Type Mineral Min. Size Max. Size Abundance (%) Unit
phenocryst plagioclase 0.0 20.0 mm
mafic mineral biotite 0.0 0.0


Manitoba Geological Survey, 2017