Cross Lake Project (1983-86)

Geologist P.G. Lenton Year 86 STATION 6351
EASTING 570227 NORTHING 6049805 ZONE 14 DATUM NAD83
Date of mapping 07/12/1986

STRUCTURAL DATA

Planar Structures:
Structure type | Strike | Dip | Separation
schistosity | 115 | 88 |
schistosity age 2 | 40 | 0 |

Linear Structures
Type | Plunge | Azimuth
S-intersection | 72 | 71

-PHOTOS
1 -cataclastic crushed zone in PGMT
2&3 -QZ-HB alteration of BO
4 -MC-TL vein
5 -anastomosing MC alteration
6 -GR-TL-HQ?? in fracture
7&8 -leached core of primary MC
9 -varied color alteration of plag.
10 -massive albite unit
11 -totally assimilated inclusion and MC alteration along contact
12 -alteration SNDS adjacent to PGMT
13 -general shot of pebbly SNDS
14

PETROLOGIC DATA

Rock Number: 1

Rock Type: sandstone
Descriptors:
pebbly
feldspathic
Field Description:

- 30 to 50 cm bedded grey biotite sandstone or subgreywacke
-fairly feldspathic, possibly lithic
-deformed and extensively altered by the pegmatite, but a few highly flattened clasts are still identifiable
-clasts that are recognized are fine grained felsic and mafic clasts
-in general bedding is chopped up by the foliation
*******************ROCK 2*********************************
-25 metres of exposure of white massive albite peg.
-this body is anomalous for this area in that its texture resembles the Yellow Beryl Dike on the north side of Beryl Island
-it's quartz poor and has massive units made up almost totally of sub to euhedral 5 to 25 cm white albite
-the only sheet silicate that appears to be part of the primary assemblage is BO
-quartz is very low, forming low interstitial masses between BO crystals
-BO shows some preferred orientation in the EW foliation indicating some act of strain during crystallization
-host consolidation of the peg. there was extensive shearing
-accompanying this shearing was extensive introduction of late acidic fluids rich in lithium, boron and possibly manganese, fluorine and chlorine and probably potassium
-this manifest itself by extensive alteration of BO to a mixture of pale greenish-amber anthrophyllite and violet holmquistite
-this is highly deformed and smeared on fracture planes and intergrown with quartz, which appears to be apart of the introduced mineralogy.
-also showing alteration are zones of pink microcline alteration in the foliation accompanied by the abundance of black shale
-the original mineralogy included some black tourmaline and red garnet, but the TL content greatly increases with alteration and is accompanied by aquamarine apatite and brownish orange, possibly specertine rich GR.
-the high acidity of the fluids is demonstrated by primary microcline crystals that have had the core completely leached out leaving only perthitic lavalia as feathery septa around the margins of the vug.
-albite also shows varied colour alteration along fractures that go from white thru reddish brown to vitreous black
-primary microcline probably represents 1 to 2 % of original mineralogy.
-all MV is 2ndary related to the alteration, but can be quite coarse.
-there is no evidence of beryl in the primary or secondary mineralogy
SAMPLES
2A Yellow mineral, has some characteristics of beryl, but is probably quartz
2B Orange garnet plus ortho-ampb
2C varied colour, alteration of albite
2D holinquistite with BO and quartz
2E large sample, shows extensive holmquistite and K-alteration of albite

Rock Number: 2

Rock Type: pegmatite
Field Description:

SEE BOTTOM NOTES OF ROCK 1 FOR STATION 6351
(-long description of field notes was typed under the wrong rock, it is clearly labelled in the Rock 1 description for station 6351)

Manitoba Geological Survey, 2017