Cross Lake Project (1983-86)

Geologist P.G. Lenton Year 83 STATION 5157
EASTING 576022 NORTHING 6048203 ZONE 14 DATUM NAD83
Date of mapping 07/20/1983

STRUCTURAL DATA

PETROLOGIC DATA

Rock Number: 1

Rock Type: pegmatite
Field Description:

ANDERSON DIKE A-2
-irregular dike prone to pinch and swell
-maximum 70 cm symmetrical zoning
-intrusive into cycle 2 conglomerate
EXOMORPHIC ZONE
-0.5 to 5 cm zone of medium to intense tourmalinization accompanied by bleaching probably caused by relocation of ferro-magnesians into coarser tourmaline leaving Quartz-feldspar rich zone. SEE PHOTOS
WALL ZONE
-0.05 to .2 mm aplitic albite and quartz with tourmaline needles, averages 1 to 2 cm, tourmaline largely normal to contact
UPPER INTERMEDIATE ZONE
-3 to 7 cm of Cleavlandite and quartz with anhedral 1 cm MC crystals
-quartz dark smoky grey
-equant tourmaline to 4 mm
-trace block metallic - ilmenite(?) (can't sample)
CORE ZONE
-up to 50 cm of buff quartz with blocky microcline (mottled pink and grey)
-veins of cleavlandite enastomosing through core zone
-no muscovite visable
-lower intermediate zone and lower wall zone identical
STRUCTURE
-see sketch in field notes
-right lateral offset on fault 67 cm (see photo)
-photo of 282 trend S offset
-photo of ptygmatic end of dike
-drag on dike margins warps foliation and pebbles in right lateral sense

PHOTOS

Location of pegmatite 5157 (Anderson A-2)

Contact of pegmatite with conglomeratic wacke country rock. Iron and magnesium are leached from the wacke while tourmaline concentrations form along the contact and invade the wacke.

Sketch map showing structural relations and symmetry of dike 5157 (Anderson A-2).

Central portion of the illustration map that shows the consistent dextral shear affecting the dike.

Dike shows dextral drag across the plane of intrusion. Dike is deformed in an open S-fold.

Pegmatite narrows to a thin veinlet that is ptygmatically folded within the plane of flattening of the wacke.

Manitoba Geological Survey, 2017