Cross Lake Project (1983-86)


Geologist    P.G. Lenton     Year    83     STATION    5046
EASTING   570847     NORTHING   6040535     ZONE   14     DATUM   NAD83
Date of mapping    06/23/1983

STRUCTURAL DATA

Planar Structures:
Structure type Strike Dip Separation
gneissosity 52 65
fault 61 82 dextral
fault 303 87 dextral

-beautiful 5 cm mylonites with pseudotachylite and dextral fault drag
-major mylonite zone 5 metres wide

PETROLOGIC DATA

Rock Number: 1

Rock Type: two component schlieric gneiss - intimate mixture of 2 major units
Descriptors:
similar to station 5006

Field Description:

-much more like 5006
-complex multi-component migmatite(gneiss) with 2 dominant phases; old gneissic tonalite (sample A) and younger grey porphyritic granodiorite (sample B) with numerous generations of pegmatitic lit, aplite and pegmatite dikes, and some minor unidentifiable granitoid phases.
sample C of 5 cm wide mylonite

Rock Number: 2

Rock Type: amphibolite
Descriptors:
massive
rock is an inclusion
schlieric
.3 by 1 metre in size

Field Description:

-partially digested, partly schlieric 30x100 cm rafts elongate in foliation

PHOTOS


Dextral mylonite with well developed pseudotachylite seams cutting the old leucocratic augen tonalite.


Close-up of the late shear showing quartz infill in extension zone (?).


Manitoba Geological Survey, 2017