the far north mapping initiative: update and future plans
TRANSCRIPT
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The Far North Mapping Initiative: update and future plans
The Far North Mapping Initiative: The Far North Mapping Initiative: update and future plansupdate and future plans
Scott Anderson and Christian BöhmManitoba Geological Survey
Scott Anderson and Christian BöhmManitoba Geological Survey
Manitoba Mining and Minerals Convention 2008Researching Manitoba’s Exploration Frontier
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The Far North Mapping Initiative….
• Major new MGS geoscience initiativefocused on Manitoba’s Far North(north of 58o north latitude)
• Manitoba Government commitment:$1.5 million over three years
• Matching funds from the GSC underthe federal government’s Geomappingfor Energy and Minerals (GEM) program
Objectives:• mapping to update 30+ year old
geological database• up-to-date assessment of mineral potential
Program commenced in fiscal 2008/2009:• GSC airborne magnetic and radiometric survey• MGS reconnaissance mapping and sampling
Major mapping programs planned for 2009, 2010
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Aboriginal Community OutreachAboriginal Community Outreach
CommunicationCommunicationEducationEducationTrainingTrainingField work employmentField work employment
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Regional settingRegional settingManitobaManitoba’’s far north*s far north*
• SE margin of Hearne craton• six geological domains• distinguished by:
cover rock-typesbasementstructural trendsmetamorphic grade
After:Weber et al., 1975Schledewitz, 1986
(*north of 58o north lat.)
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Previous work
1935: GSC route survey of Seal River (Johnston, 1935)1953: Mines Branch recon.; Caribou and Wolverine rivers (Russell, 1953)1955: Mines Branch recon.; Seal River (Milligan, 1955)1953-1957: Earliest recorded exploration; Great Island1957-1962: GSC mapping; Kasmere, Munroe, Shethanei, Tadoule lakes1971-1972: MGS Kasmere project (Weber et al., 1975)1974-1978: MGS Cochrane and Seal rivers project (Schledewitz, 1986)1975-1976: Federal-provincial URP (airborne gamma-ray spectrometric and
lake-sediment surveys)1977-1980: GSC surficial geology and till sampling1970’s: Base metal exploration; Seal River-Great IslandLate 70’s: Uranium exploration; mainly Wollaston DomainLate 80’s: Gold and base metal exploration; Great Island Domain
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Exploration Potential ofManitoba’s far north
Exploration Potential ofExploration Potential ofManitobaManitoba’’s far norths far north
Demonstrated potential for:• Volcanic-hosted
Cu-Pb-Zn-Au-Ag (VMS)• Orogenic Au• Alaskite U• Paleoplacer Au-U
Conceptual potential for:• Metasomatic/skarn REE-U-Au• Magmatic Ni-Cu-PGE• Iron-oxide Cu-U-Au (IOCG)• Sediment-hosted Pb-Zn-Ag (SEDEX)• Unconformity U• Diamondiferous kimberlite• Carbonatite Nb-P-REE
• Geoscience studies of the 1970s indicated the diverse geology andprotracted tectonic evolution of Manitoba’s far north
• Mineral exploration indicated diverse economic potential
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• Exploration hindered byextensive surficial cover
• Indirect detection methods(e.g., till geochemistry, geophysics)
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Recent MGS activities inManitoba’s far north: 2004-2006
2004200420062006
20052005
Rationale:• mitigate exploration risk by providing state-of-the-art geoscientific data• study poorly understood SE margin of the Hearne craton• further understanding of its nature, evolution and mineral potential
Methodology:• select remapping (1:50 000)• sampling of key rock-types(esp. supracrustal rocks)
lithogeochemistrySm-Nd isotope chemistryU-Pb zircon geochronology
• detailed till geochemical surveys• modest project budgets!
Objective:• updated regional bedrock and surficial
geological context
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20042004
2004 program:Sm-Nd isotope analysis on archivalsamples from the Nejanilini Domain
2004 program:Sm-Nd isotope analysis on archivalsamples from the Nejanilini Domain
• granitoid intrusive rocks (9 spls.)• probable Archean age
(Schledewitz, 1986)• Nd model ages 3.2-3.0 Ga• εNd values 0.3 to -2.7• Hearne craton margin
Enderbite gneissNejanilini LakeEnderbite gneissNejanilini Lake
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20042004
Future plans
2000 2200 2400 2600 2800 3000 3200 3400 3600
Rel
ativ
e pr
obab
ility
Lovat Lake quartz areniteLA-MC-ICPMS U-Pb zircon
2000 2200 2400 2600 2800 3000 3200 3400 3600
207Pb/206Pb age (Ma)
Rel
ativ
e pr
obab
ility
Churchill quartz areniteLA-MC-ICPMS U-Pb zircon
2568±3
~2720
~2570
2004 program:U-Pb geochronology on
detrital zircons inquartz arenites
2004 program:U-Pb geochronology on
detrital zircons inquartz arenites
Lovat LakeLovat Lake
ChurchillChurchill
~2720Lovat LakeQuartziteLovat LakeQuartzite
ChurchillQuartziteChurchillQuartziteCollected 2003
(R. Syme)
Hearne cratonsource
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20042004
20052005
2005 program:Nejanilini Lake mapping
2005 program:Nejanilini Lake mapping
• three week field program• 1:50 000 bedrock mapping of
shoreline outcrops• lithogeochemical and
geochronological sampling• surficial mapping and till sampling
Nejanilini granulite domain: Hearne craton
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Nejanilini Lake bedrock geology PMAP2005Nejanilini Lake bedrock geology PMAP2005--33
Quartzite
Semipeliticparagneiss
Biotiteenderbite
Biotiteenderbite
Kf-porph.granite
Biotitegranite
Deformed melt pod in paragneiss
2.70 Ga intrusive1.81 Ga metam.
2.56 Ga intrusive1.81 Ga metam.
2005 program:Nejanilini Lake mapping
2005 program:Nejanilini Lake mapping
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1700 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400
207Pb/206Pb age (Ma)
Rel
ativ
e pr
obab
ility
96-05-2013QuartziteNejanilini LakeLA-MC-ICPMS U-Pb zircon
1700 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400
97-05-1003Semipelitic metagreywackeNejanilini LakeLA-MC-ICPMS U-Pb zircon
96-05-2013Nejanilini LakeQuartzite
97-05-1003Nejanilini LakeGreywacke
2005 program2005 programanalytical results:analytical results:
NejaniliniNejanilini Lake samplesLake samplesdetritaldetrital zircon age datazircon age data
(LA(LA--MCMC--ICPMS)ICPMS)
Rel
ativ
e Pr
obab
ility
Rel
ativ
e Pr
obab
ility
Vastly different sources ofdetritus
1) Two distinct cover sequences?(contact relationship?)
2) Single <1.9 Ga coversequence, with distinct sourceareas?
3) Single protracted (<2.7 to <1.9Ga cover sequence?
Mainly 1.9 Gadetritus
Mainly 2.7 Gadetritus
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2004200420062006
20052005
2006 program:Kasmere and Putahow lakes mapping
2006 program:Kasmere and Putahow lakes mapping
• four week field program• 1:50 000 bedrock mapping of
shoreline outcrops• lithogeochemical and
geochronological sampling• surficial mapping and till sampling
Wollaston domain: Hearne craton margin
KasmereKasmere L.L.
PutahowPutahow L.L.
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Snyder Lake
Kasmere Lake
Tice Lake
Putahow LakeS
a s k
a t c
h e w
a n
N u n a v u t
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2006 program2006 programAnalytical results:Analytical results:
KasmereKasmere and and PutahowPutahow samplessamplesdetritaldetrital zircon age datazircon age data
(LA(LA--MCMC--ICPMS)ICPMS)
1700 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400
207Pb/206Pb age (Ma)
Rel
ativ
e pr
obab
ility
~ 2.71700 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000 3100 3200 3300 3400
Rel
ativ
e pr
obab
ility
~ 2.0
~ 2.6~ 2.7 96-06-816-1
Putahow LakeGreywacke
96-06-782-1Kasmere LakeQuartzite
1) Two distinct cover sequences?(depositional or tectoniccontact relationship?)
2) Single <1.9 Ga coversequence, with distinct sourceareas?
3) Single protracted (<2.7 to <1.9Ga cover sequence?
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• diverse supracrustal rock-types• better exposure (but not great!)• less deformed• lower metamorphic grade
The Far North Mapping Initiative• designed to address outstanding questions regarding
the geological evolution and mineral potential ofManitoba’s far north
• initial focus on Great Island Domain
Great Island domain
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94°
96°
96°
98°
98°
60° 60°
59° 59°
58° 58°
25
Kilometres
949698
25
Kilometres
NLNL
GBGBGIGI
• Supracrustal rocks disposed insynformal basins
• Include only known exposures ofvolcanic rocks in Manitoba’s farnorth (age and significance?)
• Basins clearly delineated byregional aeromagnetic surveydata, include:
• Great Island• Grand Bend• Nowell Lake
• Evidence of regionalunconformities separatingmetasediments from underlyingmetavolcanic rocks
The Far NorthMapping Initiative:
Great Island Domain
The Far NorthMapping Initiative:
Great Island Domain
Archean greenstone belts?
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The Far NorthMapping Initiative:
2008 program
The Far NorthMapping Initiative:
2008 program
2008
2008
• two week field program• reconnaissance mapping and sampling• mobe/demobe from Churchill• helicopter-supported from Sosnowski Lake
ChurchillChurchill
Sosnowski LakeSosnowski Lake
Dymond LakeAir Services Ltd.Dymond LakeAir Services Ltd.
Custom Helicopters Ltd.Custom Helicopters Ltd.
Sosnowski Lake campSosnowski Lake camp
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• visited 43 localities over four days• collected representative suite of 49 samples:
all the major rock-types, bedrock and drillcore• samples suitable for lithogeochemistry, Sm-Nd
isotope analysis and U-Pb geochronologyEppler LakeProject (active)Eppler LakeProject (active)
Polar GoldProject (1988)Polar GoldProject (1988)
The Far NorthMapping Initiative:
2008 program
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Enderbite gneissNejanilini DomainEnderbite gneissNejanilini Domain
Complex orthogneissComplex orthogneiss
PeridotitePeridotite
Granodiorite gneissGranodiorite gneiss
Porphyritic granitePorphyritic granite
Intrusive rocks:Intrusive rocks:ArcheanArchean andandPaleoproterozoicPaleoproterozoic
The Far NorthMapping Initiative:
2008 program
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Volcanic, volcaniclastic andderived sedimentary rocks: Archean?Volcanic, Volcanic, volcaniclasticvolcaniclastic andandderived sedimentary rocks: derived sedimentary rocks: ArcheanArchean??
Aphyric rhyolitebrecciaAphyric rhyolitebreccia
Felsic lapilli tuffFelsic lapilli tuff
Pillowed basalt/andesitePillowed basalt/andesite
Mafic volcanicconglomerateMafic volcanicconglomerate
PolymicticconglomeratePolymicticconglomerate
Classical Archeangreenstone belt sequence?
The Far NorthMapping Initiative:
2008 program
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Flat-lying, planar-bedded quartziteFlat-lying, planar-bedded quartzite
Paleoproterozoic cover sequence:• basal quartzite-argillite; fluvial to shallow-marine
• upper greywacke-argillite-marble;basinal marine
PaleoproterozoicPaleoproterozoic cover sequence:cover sequence:•• basal quartzitebasal quartzite--argillite; argillite; fluvial to shallowfluvial to shallow--marinemarine
•• upper greywackeupper greywacke--argilliteargillite--marble;marble;basinalbasinal marinemarine
The Far North Mapping Initiative:2008 program
FerruginousargilliteFerruginousargillite
Ball-structures ingreywacke-mudstoneturbidites
Ball-structures ingreywacke-mudstoneturbidites
Dolomitic marbleDolomitic marble
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AmygdaloidalbasaltAmygdaloidalbasalt
SulphidicargilliteSulphidicargillite
GreywackeGreywacke
AreniteArenite
North Knife RiverNorth Knife River
Paleoproterozoic cover sequence:• includes both basal and upper sections• amygdaloidal basalt flow(s)• basinal marine setting
PaleoproterozoicPaleoproterozoic cover sequence:cover sequence:•• includes both basal and upper sectionsincludes both basal and upper sections•• amygdaloidal basalt amygdaloidal basalt flow(sflow(s))•• basinalbasinal marine settingmarine setting
BaseBase--metalmetalpotential?potential?
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Monroe LakeMassive arkoseMassive arkose
Trench on pegmatiticalaskiteTrench on pegmatiticalaskite
Fracture-controlleduranophaneFracture-controlleduranophane
Pegmatitic alaskitePegmatitic alaskite
• Monroe Lake synform• Arkose intruded by
pegmatitic alaskites• U occurrences
The Far NorthMapping Initiative:
2008 program
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• Samples submitted to GSC geochronology labs• U-Pb zircon age dating:
• Isotope-Dilution Thermal-Ionization Mass Spectrometry (ID-TIMS)• Sensitive High Resolution Ion MicroProbe (SHRIMP)
• Age data to provide geochronologic context
http://gsc.nrcan.gc.ca/labs/geochron/shrimp/index_e.php
The Far NorthMapping Initiative:
2008 program
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94°
94°
96°
96°
98°
98°
59°
58°
GSC-funded High Sensitivity AirborneGeophysical Survey
GSC-funded High Sensitivity AirborneGeophysical Survey
Survey specs: • Flown fall 2008• Magnetic total field• Gamma-ray spectrometric• ~17,000 line-kilometres• 125 m nominal terrain clearance• 400 m line spacing (current 5 km)
Processed variables:• Natural air absorbed dose rate• Potassium (%)• Uranium (ppm)• Thorium (ppm)• Uranium / Thorium• Uranium / Potassium• Thorium / Potassium• Residual total magnetic field data• First vertical derivative of the
magnetic field data• Digital elevation model data
The Far NorthMapping Initiative:
2008 program
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ChurchillChurchillChurchill
Sosnowski LakeSosnowskiSosnowski LakeLake
• data collected in 2008 will providefoundation for 2009 mapping project
• planned to include:• Great Island• lower Seal River• lower North Knife River
• six to eight week field program• based out of Sosnowski Lake camp• helicopter supported
The Far North Mapping Initiative: Plans for 2009The Far North Mapping Initiative: Plans for 2009
Objective:• updated geological map of
Great Island area•Tectonostratigraphy of
supracrustal sequences• assessment of mineral potential
VMS
Au-UAlaskite U
Unconformity U
Diamondiferous kimberlite
SEDEX
IOCG
Magmatic Ni-Cu-PGE
REE-U-Au
Orogenic Au