Cross Lake Project (1983-86)

Geologist P.G. Lenton Year 83 STATION 5165
EASTING 575762 NORTHING 6048357 ZONE 14 DATUM NAD83
Date of mapping 07/30/1983

STRUCTURAL DATA

PETROLOGIC DATA

Rock Number: 1

Rock Type: pegmatite
Field Description:

DIKE A-6 BLASTED DIKE--TANCO ISLAND
-true thickness averages 3.4 m
-exomorphic effects dramatic with production of radiating tourmaline sprays in the basalt. No holmquistite visible
-SAMPLE #3 of amphibolite
-samples of complete cross section of microcline- 10 SAMPLES
Beryl -9 SAMPLES
Garnet -4 SAMPLES
Muscovite - 8 SAMPLES
1 UNKNOWN: red material from sugary late muscovitre and blue apatite veins on top of core zone
1 COLUMBITE
SAMPLE
1 -coarse plagioclase (clevelandite) near middle of core
2 -unlocated sample of platy grey albite plus saccharoidal albite
4 -lower margin saccharoidal albite
5 -upper margin saccharoidal albite
-very thin border zones rich in quartz - only 2 to 3 min
-both upper and lower wall zone are aplitic textured rock with blue apatite +/- spessartine garnet that may be saccharoidal albite.
-transition from lower wall zone to lower intermediate zone is marked by drastic grain size increase with microcline and spodumene crystals growing normal to the contact. Beryl first appears at this point, along with coarse book muscovite
-The lower intermediate zone comprises cleavlandite, quartz muscovite, apatite, beryl, columbite, minor tourmaline and traces of triphylite and abundant spodumene.
-veins of saccharoidal albite are particularly prominent below the core zone
- microcline ranges from 5-50 cm, generally equant or elongate on C-axis
-core zone is marked by the presence of pods of white quartz, containing euhedral, very large spodumene and blocky microclines to 85 cm
-veins and aggregates of very coarse muscovite are common
-beryl and columbite increase in both abundance and grain size dramatically
-Saccharoidal albite is replaced by irregular masses of late cleavlandite, accompanied by a fine sugary musc. blue apatite and spessartine
-the upper margin of the core zone has primary muscovite up to 15 cm across; blocky microclines and beryl, up to 6 cm
-the transition into upper intermediate zone is rapid with sharp decrease in the size of microcline crystals the reappearance of minor tourmaline, abundant blue apatite, more saccharoidal albite veining and a decrease in the abundance but not size of beryl
-the upper wall zone comprises grey saccharoidal albite changing into platy grey cleavlandite. The upper border zone is 1 cm of quartz and grey albite with fine acicular tourmaline.

PHOTOS

Simple geology and location grid of pegmatite at station 5165 (Anderson A-6)

Footwall contact showing fine saccharoidal-albite with tourmaline at contact, blue apatite and margin of lower intermediate zone rich in spodumene (grid reference 4.0/+4.2).

Saccharoidal albite vein in lower intermediate zone cutting across microcline and spodumene (4.1/+3.9).

Coarse log shaped spodumene at lower margin of core (6.4/-3.5).

Equant spodumene in white quartz of lower intermediate zone (6.5/-4.0).

Hanging wall contact of saccharoidal-albite in contact with cleavlandite spodumene zone at top of upper intermediate zone (1/+0).

Detail above photo (1.0/+0.0)

Tourmaline alteration of inclusion at point of western bifurcation (9.7/+1.4).

General view of dike looking due east up the base line.

Blocky microcline plus spod at upper margin of core (1.0/+1.0).

40 cm spodumene in core zone (10.5/+3.3).

General view of albitization in lower intermediate zone (7.6/+3.5).

Detail of previous photo.

Manitoba Geological Survey, 2017