Cross Lake Project (1983-86)


Geologist    P.G. Lenton     Year    83     STATION    5073
EASTING   571996     NORTHING   6041763     ZONE   14     DATUM   NAD83
Date of mapping    06/26/1983

STRUCTURAL DATA

Planar Structures:
Structure type Strike Dip Separation
schistosity 89 75

PETROLOGIC DATA

Rock Number: 1

Rock Type: tonalite
Descriptors:
schlieric or schlieren present
leucocratic

Field Description:

-Minor component of megacrystic granodiorite.
Unusual feature:
Because of less deformation and shearing here there are preserved blocky blue-grey an pink microcline megacrysts upto 20 cm floating in the tonalite. They are not dike or pegamtite related and don't appear to be structural features such as boudins. I can see no explanation for these other than magmatic megacrysts.

Textural Features
Type Mineral Min. Size Max. Size Abundance (%) Unit
phenocryst potassium feldspar 0.0 20.0 cm

Minerals of Note
Mineral Abundance (%)
biotite
garnet

Rock Number: 2

Rock Type: amphibolite
Descriptors:
layered
hornblende-epidote bearing
occurs as a raft

Field Description:

-many large rafts of highly folded mafic amphibolite.
-contains large deformed pods with hornblende-epidote rims and webwork of white quartz through a core of pale orange carbonate mineral - could be siderite - sample 2B carbonates for x-ray I.D.

Minerals of Note
Mineral Abundance (%)
garnet

Rock Number: 3

Rock Type: pegmatite
Descriptors:
granitic
aplitic
dike

Field Description:

-Pegmatite and aplite dike swarms. Samples of aplite.
-Varicolored blocky microcline in grey quartz.
-Biotite only mafic.
-Garnet most abundant in quartz-poor margins.

Minerals of Note
Mineral Abundance (%)
garnet
biotite


Manitoba Geological Survey, 2017