Cross Lake Project (1983-86)

Geologist P.G. Lenton Year 83 STATION 5089
EASTING 568961 NORTHING 6044035 ZONE 14 DATUM NAD83
Date of mapping 07/04/1983

STRUCTURAL DATA

Planar Structures:
Structure type | Strike | Dip | Separation
schistosity | 275 | 84 |

-it appears the 2 granodiorite types which are distinctly different on this outcrop may have been responsable for confusion in that highly tectonized outcrops have not allowed differentiation.
-suggest a cross check of previous samples for colour index and intensity of fabric

PETROLOGIC DATA

Rock Number: 1

Rock Type: tonalite
Descriptors:
leucocratic
Field Description:

-relativly undeformed zone with little intrusion of pegmatitic matierial
-age relation to younger intrusives fairly obvious in that rock types 2 and 3 both truncate pegmatite/tonalite layering of S1 age.

Textural Features
Type | Mineral | Min. Size | Max. Size | Abundance (%) | Unit
groundmass grainsize |  | 0.0 | 1.0 |  | mm
mafic mineral |  | 0.0 | 0.0 | 4.0 | %

Rock Number: 2

Rock Type: granodiorite
Descriptors:
porphyritic
biotite
Field Description:

-age relations indicate intermediate age between types 1 and 3
-exhibits distinct intrusive relations into tonalite, but has its own distinct S2/S3 fabric, not found in rock type 3.
-the amount of injected matierial (mainly 1 to 3 cm granitic aplite and peg.) is much greater than rock type 3

Textural Features
Type | Mineral | Min. Size | Max. Size | Abundance (%) | Unit
mafic mineral |  | 0.0 | 0.0 | 8.0 | %

Rock Number: 3

Rock Type: granodiorite
Descriptors:
massive
biotite
Field Description:

-relativly featureless massive grey sandy textured rock
-appears to be youngest of granitic intrusion.
-it is highly deformed and intruded by late pegmatites but largely lacks the early granitic lit and strong S2 fabric

Textural Features
Type | Mineral | Min. Size | Max. Size | Abundance (%) | Unit
mafic mineral | biotite | 0.0 | 0.0 | 15.0 | %
groundmass grainsize | biotite | 0.0 | 0.4 |  | mm

Rock Number: 4

Rock Type: pegmatite
Field Description:

-plagioclase rich schlieric pegmatite, biotite strung out in S3 foliation
-feldspars partially granulated with some augen developement

Minerals of Note
Mineral | Abundance (%)
biotite
garnet
magnetite

Manitoba Geological Survey, 2017