Cross Lake Project (1983-86)


Geologist    P.G. Lenton     Year    85     STATION    6061
EASTING   570107     NORTHING   6047831     ZONE   14     DATUM   NAD83
Date of mapping    06/19/1985

STRUCTURAL DATA

Planar Structures:
Structure type Strike Dip Separation
cataclastic foliation 269 78

PETROLOGIC DATA

Rock Number: 1

Rock Type: gneiss
Descriptors:
mesocratic
tonalitic

Field Description:

-grayish brown weathering with dark grey surface, strong schistocity
-contains inclusions of massive ampb
-unit ut by rock type 2, then cut by rock type 3 at which time an anatomozing vein network of feldspathic, HB-epidote seams formed and then was cut by rock type 4

Minerals of Note
Mineral Abundance (%)
hornblende

Rock Number: 2

Rock Type: tonalite
Descriptors:
leucocratic

Field Description:

-dikes up to 1 m or more with an associated vein swarm in rock type 1.
-this rock is sheared and shows the same HB-epidote alteration as the earlier unit

Rock Number: 3

Rock Type: amphibolite
Descriptors:
massive
gabbroic

Field Description:

-foliated, veined, old gabbroic intrusive that contains inclusions of TNLT gneiss
-this is cut by fine feldspathic stringers and quartz veins but does not show same HB-epidote alteration as earlier units
-gabbro may have caused the alteration in the TNLT's

Rock Number: 4

Rock Type: diabase
Descriptors:
foliated

Field Description:

-60 cm dike of old mafic intrusion
-strong fabric and deformed margins
-this unit crosses TNLT gneiss and truncates veins of Rock type 2 and HB-epidote alteration seams
-fine grained and was probably pyroxene bearing
-not a Molson

PHOTOS
1 diabase cutting TNLT Gneiss
2 TNLT gneiss with leuc TNLT veins and alteration veins cut by diabase
3 Gabbro ampb with inclusions of old TNLT
4 General shot of Gabbro ampb
5 ampb inclusions in TNLT gneiss
6 alteration veins cutting and offsetting leuco TNLT
7 leuco TNLT cutting TNLT gneiss


Manitoba Geological Survey, 2017