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