Cross Lake Project (1983-86)

Geologist P.G. Lenton Year 84 STATION 5439
EASTING 575885 NORTHING 6059294 ZONE 14 DATUM NAD83
Date of mapping 06/21/1984

STRUCTURAL DATA

Planar Structures:
Structure type | Strike | Dip | Separation
schistosity | 61 | 86 |

Minor Folds
Type | Symmetry | Strike | Dip | Plunge | Azimuth
similar fold | Z | 46 | 89 | 0 | 0

Linear Structures
Type | Plunge | Azimuth
clast elongation | 0 | 0

PETROLOGIC DATA

Rock Number: 1

Rock Type: conglomerate
Descriptors:
greywacke matrix
Field Description:

PHOTOS
1 -general matrix support char.
2 -large rhyolite clasts
3 -general appearance of rock 2
-dominantly mafic volcanic clasts with subordinate hornblende-diorite gabbro, some tonalite and several quartz-phric dacite and rhyolite clasts
-clasts: <5% tonalite, 2 to 3% acid volcanic sediment ( siltstone dominates)
- 5% intermediate and mafic intrusive 5 to 10%
- rest basalt and andesite
-well bedded with excellent clast organization and sorting in layers
-some beds have more tonalite or rhyolite
-matrix is dirty biotite-greywacke

Rock Number: 2

Rock Type: conglomerate
Descriptors:
mafic matrix
Field Description:

-matrix supported in hornblende rich silty wacke
-clast size variable from granule to large pebble for mafics with a few giants in cobble gabbro and hornblende diorite
-HB lacks rhyolite clasts
-very little organization or sorting
-no troughs or wacke beds
-matrix probably basaltic tuffaceam material
-looks like reworked debris flow

Rock Number: 3

Rock Type: conglomerate
Descriptors:
mafic matrix
Field Description:

-essentially identical layer to #2 but has 4 to 5 % of ultramafic pyroxenite clasts

Rock Number: 4

Rock Type: conglomerate
Descriptors:
rhyolite clast
Field Description:

-clast supported conglomerate with abundant rhyolite and quartz-phyric rhyolite clasts
-sample a rep
-sample b sample of rhyolite clast, 10-15% rhyolite, quartz porphyry rhyolite and dacite, <5% tonalite-granodiorite 20 to 25% feldspar quartz porphyry, 10% gabbro-diorite, rest is mafic volcanic in a hornblende-wacke matrix although not enough to support clasts
PHOTOS
4 -rhyolite clast population
5 -interbeds of mafic wacke
6 -interbeds of mafic lithic wacke

Rock Number: 5

Rock Type: greywacke
Descriptors:
lithic
mafic
Field Description:

-.5 to 1 m beds of mafic wacke with abundant granule to small pebble lithic fragments
-usually as interbeds in #6
-generally sorted, sometimes graded
PHOTO
7 -general texture

Rock Number: 6

Rock Type: greywacke
Descriptors:
massive
mafic
Field Description:

-massive, almost featureless, rare instances of fine laminar bedding and cross bedding green weathering
-strongly resembles Belcher Island wackes

Minerals of Note
Mineral | Abundance (%)
hornblende

Rock Number: 7

Rock Type: greywacke
Descriptors:
lithic
ultramafic composition
Field Description:

-dark chloritic-green weathering massive wacke--rare mafic clasts
-ungraded, poor bedding definitions
-generally as massive dumb types of deposits
-IN GENERAL SECTION APPEARS MIXED--FOLDING TO EXTREME AS A SERIES OF 1 TO 5 M Z FOLDS THAT SO CONFUSES THE PICTURE I CAN'T TELL WHAT IS UP SECTION

Manitoba Geological Survey, 2017