Cross Lake Project (1983-86)

Geologist P.G. Lenton Year 83 STATION 5041
EASTING 570986 NORTHING 6041657 ZONE 14 DATUM NAD83
Date of mapping 06/23/1983

STRUCTURAL DATA

Planar Structures:
Structure type | Strike | Dip | Separation
schistosity | 220 | 0 |

Dikes and Sills:
Rock Number | Type | Width (m) | Strike | Dip
3 | diabase | 1.55 | 142 | 80

Linear Structures
Type | Plunge | Azimuth
rodding | 60 | 115

PETROLOGIC DATA

Rock Number: 1

Rock Type: tonalite
Descriptors:
schlieric or schlieren present
leucocratic
biotite lenses
weakly megacrystic
light grey
weakly deformed
Field Description:

-grey tonalite/granodiorite
- appears to be the older unit but not as severly deformed or sheared as at other locals. Weathers pale greyish-white with a well defined lensoid BO segregation visible on fresh surface.
-weakly megacrystic-felspars 2 to 3 mm in an average 1 to 1.5 mm grain size

Textural Features
Type | Mineral | Min. Size | Max. Size | Abundance (%) | Unit
phenocryst | plagioclase | 2.0 | 3.0 |  | mm
mafic mineral | biotite | 0.0 | 0.0 |  |
groundmass grainsize |  | 0.0 | 1.5 |  | mm

Rock Number: 2

Rock Type: basalt
Descriptors:
pillowed
selvages present on pillows
occurs as a raft
epidote veins
Field Description:

-first convincing pillowed volcanic seen in Clearwater Bay.
-black weathering massive amphibolite with anastomosing veinlets of hornblende + plagioclase +/- epidote that look like selvages

Minerals of Note
Mineral | Abundance (%)
hornblende
plagioclase
epidote

Rock Number: 3

Rock Type: diabase
Descriptors:
massive
Molson dike
155 cm wide
diabasic
dark green
Field Description:

-155 cm maximum width with 10 cm chill margin
-sample A 40 cm into dike
-sample B lower contact chill margin
-weathers dark green with some remnant plagioclase lathesd; diabasic texture

PHOTOS

Fine grained greenish black diabase dike. The unfoliated nature, clean sharp contacts and strike of 142° suggests this may be a Mackenzie dike rather than an offshoot of the Molson dikes.

Flattened and stretched amphibolite raft that still has convincing characteristics of pillowed basalt.

Manitoba Geological Survey, 2017