Clay Distribution Patterns and Alteration in the Athabasca ...

Clay Distribution Patterns and Alteration in the Athabasca Basin

Northern Saskatchewan

Ken WasyliukChief Geochemist

Outline• Introduction

– Clay Mineralogy– Analytical Techniques– Common Sampling Techniques– Other Important Information

• Review Historical Information• Clay Distributions

– Regional Scale– District Scale– Deposit Scale– Drill Hole/Hand Sample

• Current Sandstone Clay Alteration Model• Clay Distribution in Basement Rocks• Exploration Highlights / Implications• Kaolin Group “Minerals” in the Athabasca Basin

Clay Mineralogy• Small hydrous layer silicates, generally of low temperature

origin, that are part of the phyllosilicate family (Weaver, 1989)– without the size (<2 µm or <4 µm) connotation (dickite booklets

seen in thin section >50 µm in size)• Common in Athabasca Group:

– Illite (potassium aluminum silicate)• (K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2

– Kaolin Group (Dickite, Kaolinite, S-Kaolinite) aluminum silicates• Al4Si4O10(OH)8

– Chlorite (Sudoite, Mg and Fe chlorites)• (Al6Mg4)(Si6Al2))O20(OH)16

– Dravite (Magnesiofoitite, Zhang, 2000)• [](Mg2Al)Al6(BO3)3(Si6O18)(OH)4

Analytical Techniques

• Normative – calculated illite, chlorite, kaolinite ±dravite proportions based on the assumption that all the Al2O3, MgO, K2O and B contents are associated with the clay minerals

• X-ray Diffraction – either whole rock or clay separates

• Shortwave Infrared Reflectance Spectroscopy – PIMA or ASD

Short-wave Infrared Reflectance Spectroscopy

• first introduced to Athabasca Basin in 1994 by Steve Earle of Grasswood Geoscience

• portable, rapid and relatively inexpensive

• utilizes 1300 - 2500 nm wavelength region of electromagnetic spectrum

• capable of providing structural and chemical information

• capable of distinguishing the common clay minerals in the Athabasca Basin

• most importantly distinguishes kaolin polytypes dickite and kaolinite

• limited by the quality of the available spectral library and is not able to provide a total clay content

Common Sampling Techniques

• Composite Samples – boulder or drill core– regular intervals– primarily sandstone

• Systematic Samples– regular intervals– sandstone or basement lithologies

• Selective Samples– sandstone or basement lithologies

Comparison Systematic Sampling Intervals

best compromise between samplerepresentivity and efficiency was found toa standard five meter sample interval

Other Important Information

• Mapping / Drill Logging• Petrography• Isotopes (stable and radiogenic)• Geochemistry (multi element with majors

and pathfinders)All of which will assist in placing any

observed distribution patterns into the proper geological context

Ore Formation Models(Hoeve and Quirt, 1984; Fayek, 1996)

graphiticparagneisssilicified zone

massive quartz

SIMPLE TYPE

COMPLEX TYPEfaults

unconformity

Reduced Basement

-REEs, Ni, Co, As

-lower total REE contents-HREE/LREE>1

-HREE/LREE 1-high total REE contents

Oxidized BasinalFluids

-U, HREEs, Cu

W E

Fluids

-Ni, Co, Cu, As

MIS96039

Historical Information

Clay Alteration Models(Earle and Sopuck, 1989)

Regional Illite Distributions(from Earle & Sopuck, 1989)

DAWNRABBIT

McCLEAN

MIDWEST

McARTHUR RIVER

CIGAR

KEY LAKE

KEY

% of samples with >60% I/I+Kfrom 10m above unconformity toto top of sandstone.

>25

>50

MC97008

Regional Clay Distributions(from Earle & Sopuck, 1989)

KEY LAKE

MCARTHUR RIVER

Regional Clay Distribution Patterns

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Dominant Clay MineralogyDickite >80%Dickite >60,<80%Mixture Illite & DickiteIllite >60%,<80%Illite >80%Mixture Illite & KaoliniteKaolinite >60%Mixture Kaolinite & DickiteChlorite >40%Dravite >40%Mixture all Clay Species (Dickite)Mixture all Clay Species (Kaolinite)

0

Kilometres

5 10 15 20 25

Northeastern Athabasca Basin

MFd

MFc

MFb

Larocque Lake

Natona Bay

Cigar Lake

Rabbit Lake

Q11A

McClean LakeSue

Dawn Lake

Thorburn Lake

Midwest Lake

Dominant Clay MineralogyDickite >80%Dickite >60,<80%Mixture Illite & DickiteIllite >60%,<80%Illite >80%Mixture Illite & KaoliniteKaolinite >60%Mixture Kaolinite & DickiteChlorite >40%Dravite >40%Mixture all Clay Species (Dickite)Mixture all Clay Species (Kaolinite)

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Kilometres

5 10 15 20 25

Southeastern Athabasca Basin

MFdMFc

MFb

McArthur River

Key Lake

Zone M

Zone K

Southeastern Athabasca Basin – Kaolinite and Dickite Distributions

Northern Athabasca Basin

Deposit Scale Clay Distribution Patterns

Maverick●

Maverick Deposit – Section ML-61 Looking West

MC97006

McArthur River ProjectClay Estimates in Boulders

% Illite

% Chlorite

% Kaolinite

% Dravite

% D ickite

Per

cent

cla

y P

rop

ort

ion

1 .45 km E 2.00 km W0.00 (DEPO SIT)

Drill Hole and Hand Sample Clay Distribution Patterns

Illite

Dravite

Chlorite

DraviteChloriteKaolinite

Illite&

Dickite

Illite

Silicification

Clay BoundIllite, Chlorite

Hematite

DickiteMinorKaolinite

SANDSTONE ALTERATION MODELS (1999)

UC

&

Variable

SilicificationVariable

Dickite

Illite

Kaolinite

Clay Distributions in Basement Rocks

Hole Name :ES-214

EPT_Study.dhx

Segment Start Depth :0.00 Segment End Depth :396.85

AlterationRabbi t_Roc k s Gamma Syst em at ic_ausspec e m a t ic _ M in e r Syst em at ic_ausspec e m a t ic _ M in e r a Syst em at ic_ausspec Syst em at ic_M I NSPEC Syst em at ic_ausspec s tem atic _M inera lo GeochemDepths

Depth At Index oc k _ty pe_c o U3O8 Illite_comp l i te_s y m Illite_xtal Sm ect it e_sym Chl_Cb_prop ILL_C1CHL_C2DICK_C3

Chl_comp Chlor it e_sym io ti te_s y mFe2O3t tri-acidwt %

MgO tri-acid wt%

MnO tri-acid wt%

K2O tri-acid wt%

Na2O tri-acid wt%

B Na2O2 fusionppm

Ba tri-acid ppm Zn Partial ppm As Partial ppm Mo Partial ppm U Fluorimetry Partialppm

Scale 1:2042.670373 11/20/03 21:14:13

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O B

S M P L

P E G M

S M P L

A R K S

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P E L T

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A R K S

P E G M

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P E G M

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Exploration Highlights (Basement)

• illite/chlorite proportional increases with alteration intensity (somewhat controlled by lithology and not manifested in chemistry)

• biotite and Fe chlorites preserved in fresh pelitic gneisses

• Fe depletion (bleaching) manifested in higher Mg chlorites

• Na-Ba-Zn is depleted from all lithologies and intensifies with alteration

• U-B plus typical pathfinders (Ni,Pb,As,Mo etc.) enriched in all lithologies

Hole Name :ES-296

EPT_Study.dhx

Segment Start Depth :0.00 Segment End Depth :434.50

AlterationRabbi t_Roc k s Gamma Syst em at ic_ausspec e m a t ic _ M in e r Syst em at ic_ausspec e m a t ic _ M in e r a Syst em at ic_ausspec Syst em at ic_M I NSPEC Syst em at ic_ausspec s tem atic _M inera lo GeochemDepths

Depth At Index oc k _ty pe_c o U3O8 Illite_comp l i te_s y m Illite_xtal Sm ect it e_sym Chl_Cb_prop ILL_C1CHL_C2DICK_C3

Chl_comp Chlor it e_sym io ti te_s y mFe2O3t tri-acidwt %

MgO tri-acid wt%

MnO tri-acid wt%

K2O tri-acid wt%

Na2O tri-acid wt%

B Na2O2 fusionppm

Ba tri-acid ppm Zn Partial ppm As Partial ppm Mo Partial ppm U Fluorimetry Partialppm

Scale 1:2236.462837 11/20/03 21:15:41

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Exploration Highlights (Sandstone)• dickite is commonly developed in regional holes away from

mineralization• illite, kaolinite, dravite and chlorite are commonly developed near

mineralization• similar clay distributions occur around mineralization in both north

and in south (ie. Dawn Lake)dickite--->illite--->kaolinite+-dravite/chlorite

• these clay distributions can occur on all scales (from individual faults within drill holes, to deposit, district and regional)

• regional clay alteration patterns are reflected in both the drill core and boulder geochemistry

• alteration crosscuts stratigraphy in the Manitou Falls Formation• variations of clay patterns at all scales indicates that the clay

minerals are sensitive indicators of hydrothermal and diageneticevents– however the variations at the regional, local and deposit scale also

show the need for consistent sampling and the establishment of background clay patterns

• use clay distributions as a vector towards hydrothermal centres and mineralization

Kaolinite Group “Minerals” in the Athabasca Basin

Dickite (standards)

Kaolinite (standards)

S-Kaolinite (Mixed Layered)Athabasca

Basin

1400 nm

Athabasca Sampleswith Unique SWIR Characteristics

100% Kaolinite

100% Dickite

90% Kaolinite/10% Dickite

10% Kaolinite/90% Dickite

50% Kaolinite/50% DickiteExperimental SamplesMechanical Mixtures

MINERALIZED REGIONAL

Alteration haloes

d -

U/C

k -

k -2

d -

k -

d -

k -k -

Late Mineralization

Late Fractures MineralizationBasement

Paleoregolith

k -Sandstone

d -

k -2

k -

k -

Regional

d -

L e g e n d

k = kaolinite d = dickite k = S-kaolinite (mixed layer)

Alteration halos

Ore

Fault zone

AthabascaGroup

All MembersManitou Falls

Formation

WollastonGroup

BARREN

2

Fractures

k -

KAOLINITE MINERAL SETTINGS IN ATHABASCA BASIN

SETTING OF KAOLINITE GROUP MINERALSWITH LOW VALUES


Alteration haloes

d -

U/C

D = - 90

k - D = - 150

k - D = - 942

A7O-024

M121/BL10

A7O-020

d - D = - 115

k - D = - 130

RL8D LMS-73.011

RD8C-9009

k - D = - 86ML-7-411.3 m

k - D = - 176M204/547

LateMineralization

MineralizationBasement

k - D = - 158MAC178-428.7

Sandstone

k - D = - 168M132/BK2

L e g e n d

k = kaolinite d = dickite

Alteration halos

Ore

Fault zone

AthabascaGroup


Formation

WollastonGroup

BARREN

2

Fractures

D

k = S-kaolinite (mixed layer)

< -90 ‰

SETTING OF KAOLINITE GROUP MINERALSWITH HIGH VALUES


Alteration haloes

d -

U/C

D = - 56

k - D = - 52MAC121-BL-7

DDHBF-130-60

d - D = - 58

k - D = - 58

SP118-55

ML-7-232.0 m

d - D = - 4942352

k - D = - 45CQ16-225.6 m

Late Mineralization


Paleoregolith

Sandstone

d - D = - 58

k - D = - 522

HAM05-23

42095-97

k - D = - 42EP033/180.5

Regional

D = -53DA9D Q923 210.4 m

d -

L e g e n d


Alteration halos

Ore

Fault zone

AthabascaGroup


Formation

WollastonGroup

BARREN

2

Fractures

D

Paleoregolithk - D = - 59PK7D-PK31-10


~ -40 to -60 ‰

Polytype(# of samples)

δD (‰)(mean)

δ18O (‰)(mean)

Undifferentiated (13) -35 to –167 (-90) 8.8 to 12.7 (12.5)

Dickite (19) -49 to –116 (-72) 9.2 to 14.1 (11.8)

S-Kaolinite (3) -52 to –94 (-67) 9.8 to 12.7 (11.4)

Kaolinite (44) -45 to –176 (-121) 6.3 to 17.1 (11.7)

KAOLINITE MINERAL SETTINGS IN ATHABASCA BASINISOTOPIC COMPOSITION RANGES OF KAOLINITE

GROUP MINERALS


Alteration haloes

d -

U/C

D = - 87 to -116

k - D = - 111 to -168

k - D = - 942

0 = 9.2 to 13.818

0 = 9.4 to 11.918

0 = 9.818

d - D = - 59 to -115

k - D = - 52 to -144

0 = 10.2 to 12.618

0 = 11.1 to 16.718

d - D = - 490 = 11.518

k - D = - 580 = 12.718

k - D = - 105 to -1760 = 7.6 to 16.018

Late Mineralization


Paleoregolith

k - D = - 147 to -1670 = 6.3 to 12.918

Sandstone

d - D = - 55 to -62

k - D = - 52 to -542

0 = 11.7 to 14.518

0 = 11.6 to 12.718

k - D = - 148 to -1680 = 10.1 to 10.718

k - D = - 58 to -610 = 11.4 to 12.718

Regional

D = -530 = 10.418

d -

L e g e n d


Alteration halos

Ore

Fault zone

AthabascaGroup


Formation

WollastonGroup

BARREN

2

Fractures

k -


Summary• Kaolinite

• alteration haloes (mineralized or “barren”)

• “bleached” zone of paleoregolith

• faults and fractures (basement and sandstone)

• Dickite• regional sandstone • alteration haloes (not

common)• faults and fractures

(basement and sandstone)• S-Kaolinite

• regional sandstone• alteration haloes (rare)


Alteration haloes

d -

U/C

k -

k -2

d -

k -

d -

k -k -

Late Mineralization


Paleoregolith

k -Sandstone

d -

k -2

k -

k -

Regional

d -

L e g e n d

k = kaolinite d = dickite k = S-kaolinite (mixed layer)

Alteration halos

Ore

Fault zone

AthabascaGroup


Formation

WollastonGroup

BARREN

2

Fractures

k -

KAOLINITE MINERAL SETTINGS IN ATHABASCA BASIN

Deilman Pit Samples(Ramaekers, 1989)

Sample Paragenesis Kaolin Polytype(SWIR)

D-450-01A early & late kaolinite

D-450-03 late kaolinite

D-458-05A early & late kaolinite

D-458-05B early kaolinite

D-458-11 early kaolinite



D-466-39 early kaolinite

D-474-22 early and late kaolinite

D-474-26 early and late kaolinite

Spectral Analysis of Paragenetically “Late” Kaolinite (Hubregtse, 1987)

Drill Hole Depth Kaolinite Polytype (SWIR)

RL-44A 400.00 dickite

RL-16 185.00 kaolinite

RL-36 451.5 dickite

Implications of Kaolinite Polytype Distributions

• Temperature, depth of burial, fluid to rock ratios and time (duration) together not individually control kaolinite polytypism in the Athabasca Basin

• Dickite and kaolinite are present in alteration haloes as well as fractures and faults where high fluid fluxes would be anticipated

• Mixed layer kaolinite in regional sandstone suggests the polytype transformation process has not been achieved

• All kaolinite polytypes can have low δD (< -90 ‰) values providing evidence that preferential and retrograde hydrogen exchange with post-Cenozoic meteoric waters occurs without dissolution or reprecipitation along selected post Athabascastructures.

• The present distribution of kaolinite polytypes are controlled by earlier processes such as diagenesis and ore formation– Kaolinite polytype distribution is not a product of late

meteoric waters• Clay mineralogy can be related to the primary fluids involved in

the ore forming process and as such can be used to model paleofluids in the Athabasca basin, particularly those associated with uranium mineralization (can be used as a vector towards hydrothermal centres)

Clay Distribution Patterns and Alteration in the Athabasca ...

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