Bird River Belt in southeastern Manitoba: a
Neoarchean volcanic arc in the Western
Superior Province
Paul Gilbert
Manitoba Geological Survey
Location of
Bird River
Belt
Bird
Bird River
River Belt
Belt
Winnipeg
Winnipeg
Bird River Belt projects initiated in 2005
Paul Gilbert (Manitoba Geological Survey) ~
1: 20 000 scale mapping
Manuel Duguet (Post doctoral student, Univ. of Waterloo) ~
Regional mapping (1: 50 000 scale) with focus on structural geology
Paul Kremer (MGS), Caroline Mealin ~
Economic geology theses (MSc Univ. of Waterloo)
TANCO pegmatite, Bird River Sill
Outline of presentation
1. Regional setting and stratigraphy of BRB
2. Volcanic geochemistry
3. Regional tectonic evolution
4. Economic geology
Bird River Belt regional setting
MANITOBA
ONTARIO
BIRD
RIVER
SEPARATION LAKE
Bird River Belt
stratigraphy
1. MORB-type volcanic rocks [ >2745 Ma ]
2. Continental arc-type sequence [ ~2730 Ma]
3. Younger sedimentary rocks [~ 2704 Ma]
Bird River Belt stratigraphy
Northern MORB type
Bird River Sill
ERS
Flanders
Lake Fm
North panel arc
Booster Lake Fm
South panel arc
WRS
Southern MORB type
Bird River Belt North Panel
Highway Junction area
BRB North Panel –
highway junction
area
Diverse arc assemblage
Northern MORB
Fm
Peterson Creek Fm
Bird
River
Sill
Booster Lake Formation
Booster Lake Fm
BRB North Panel – cross-section
Line of cross-section
Peterson Creek Fm
SOUTH
NORTH
upper
Diverse
Arc
assemblage
conglomerate
lower
BRB North Panel – composite
stratigraphic section
SOUTH
South
NORTH
North
Booster
Lake
Formation
Peterson
Creek
Formation
Polymictic
conglomerate
Diverse Arc
assemblage
Line of composite section
South
SOUTH
Bird River
Sill
North
NORTH
MORB-type basalt formations
Northern MORB-type basalt
Pillowed basalt
Southern MORB-type basalt at Winnipeg River
Megaphyric basalt
Polygonal jointing
Altered pillowed basalt
Arc-type rocks (highway junction area)
SOUTH
Booster Lake
Formation
Peterson
Creek
Formation
Polymictic
conglomerate
Diverse Arc
assemblage
Bird River Sill
NORTH
Spherulitic rhyolite
Arc-type rocks (highway junction area)
In-situ breccia,
flow lamination
Booster Lake
Formation
Peterson
Creek
Formation
Heterolithic
volcanic breccia
Diverse Arc
assemblage
Bird River Sill
Volcaniclastic
mass-flow
Turbidite
Bird River Belt South Panel
(= Bernic Lake Formation)
South Panel (Bernic Lake Formation)
Western Bird River Belt:
Bernic Lake Formation
Bird River Belt south panel ~ Bernic Lake
Formation
N
Upper BLF
N
Middle BLF
Upper BLF
Middle BLF
S
Lower BLF
Lower BLF
S
Bernic Lake Formation
Upper BLF
volcanic breccia
N
Upper
BLF
Middle
BLF
Middle BLF
pillow basalt &
alteration
Lower
BLF
S
Lower BLF altered felsic volcanic bx
BRB South Panel
BRB North Panel
N
SOUTH
Booster Lake
Formation
Booster Lake
Formation
Upper
BLF
Peterson
Creek
Formation
Diverse Arc
assemblage
Bird River
Sill
NORTH
Middle
BLF
Lower
BLF
Southern
MORB type
S
Bird River Belt ~
Geochemistry
of volcanic rocks
Bird River Belt ~ main
tectonostratigraphic components
Northern MORB type
Booster Lake Fm
3. Late orogenic sedimentary rocks
[~ 2700 Ma]
North panel CA arc
2. Continental arc-type sequence ~
(a) North panel calcalkaline [ 2731 ±1 Ma]
(b) South panel tholeiitic
[ 2725 ±1]
South panel TH arc
Southern MORB type
1. MORB-type volcanic rocks [ >2745 ±5 Ma]
Bird River Belt ~
All volcanic rocks
North Panel
South Panel
North Panel
South Panel
Jensen (1976)
Irvine and Baragar (1971)
Northern and Southern MORBtype Formations
MORB-type Formations ~
- Oldest volcanics
- Intruded by 2745 Ma Bird River Sill
- Back-arc, rift-associated
Northern and
Southern MORBtype Formations
Bird River Belt
North Panel
mafic to intermediate
volcanic rocks
BRB North Panel
Mafic to intermediate
volcanic rocks
BRB north panel
volcanic rocks
Bernic Lake Fm south part
North Panel
Bernic Lake Fm north part
Mafic to
intermediate
volcanic rocks
South Panel
Bernic Lake Formation
in eastern BRB
mafic to intermediate
volcanic rocks
BRB north panel felsic
volcanic rocks
North Panel
Bernic Lake Fm south part
Bernic Lake Fm north part
Felsic volcanic
rocks
South Panel
Bernic Lake Formation
in eastern BRB
felsic volcanic rocks
Bird River Belt South Panel
Bernic Lake Fm – Main part (E)
Bernic Lake Fm – Main part (W)
Bird River Belt North vs South Panels
North Panel
North & South Panels
North Panel
South Panel (Bernic Lake Fm)
Bernic Lake Formation ~
Main vs Upper part
Bernic Lake Formation ~
Main and Upper parts (East)
Bernic Lake Formation ~
Main and Upper parts (West)
Bird River Belt ~
Tectonic affinity of volcanic rocks
Pearce (1983)
Bird River Belt ~
Tectonic affinity of volcanic rocks
Wood (1980)
Bird River Belt ~
Tectonic affinity of volcanic rocks
Gorton and Schandl (2000)
SUBDUCTION-RELATED
EXTENSION-RELATED
Bird River Belt ~
Nd-Sm isotope data
Nd-Sm isotope data
εNd of mantle = +1.4 at 2.7Ga
Bird River Belt ~
Tectonic history
Western Superior Province
MANITOBA
ONTARIO
Section line in next slide
North Caribou ST
Uchi SP
BIRD
RIVER
English River SP
Winnipeg River SP
Tectonic history of southwest Superior Province
North
Caribou
Superterrane
N
S
2850 – 2750 Ma ?
N
S
Winnipeg
River
Subprovince
Tectonic history of southwest Superior Province
North
Caribou
Superterrane
N
N
S
S
Winnipeg
River
Subprovince
Bird River Belt economic geology
MaskwaDumbarton Mine
(Cu, Ni)
1969-1976
Tanco Mine
(Li, Cs, Ta)
1969 - present
Bernic Lake
development
(1929, 1957)
Bernic Lake
1957
Montgarry
Shaft
headframe
Bernic Lake 1929 Jack
Nutt Mines headframe
Bernic Lake 1929
crusher, mill buildings
assay office
Bernic Lake
(recent)
Bernic Lake 1929 Jack
Nutt Mines headframe
Bird River Belt ~
current exploration for base metals and PGE
Summary
‰ Neoarchean Bird River Belt consists of arc-type rocks that were deposited
on the margins of a flanking continental terrane. Arc-type components
include tholeiitic, calc-alkaline and MORB-type basalts.
‰ Tectonic setting is continental arc – seismic data suggest the BRB rests on
continental lithosphere. Volcanic rocks primarily intermediate to felsic (not
bimodal type sequence) due to influence of continental lithosphere
underplating.
‰ Progression from subduction to an extensional tectonic setting is
documented in the BRB from North to South panels.
‰ Current active mineral exploration for base-metals and PGE is focused on
Bird River Sill and related intrusions, as well as MORB-type basalt
formations. New sources for rare-element pegmatites akin to Tanco deposit
are also being sought.