By: Graham Bubner Chris GaughanChris Gaughan Paul Leeverssaemc.com.au/archive/2004/04onesteel.pdf · • brief history of the development of ... of hole from downhole logging. 60

The Iron Magnet DepositBBy:Graham BubnerChris GaughanChris GaughanPaul Leevers

Mines Presentation - Jan 2004

INTRODUCTION

• LOCATION

• BRIEF HISTORY OF THE DEVELOPMENT OF THE IRON MAGNET DEPOSITTHE IRON MAGNET DEPOSIT

• GENERAL GEOLOGY OF IRON MAGNET

• MINERALISATION CONTROLS AND STYLES

• GEOPHYSICAL SIGNATURES


• CURRENT WORK

LOCATION

Port Augusta

WHYALLAIron Knob

Iron BaronIron Duke

IRON KNOB(CLOSED)

N

South Australia

ADELAIDE

Kangaroo Island

Ardrossan

Coffin Bay

Cooyerdoo

Katunga Hills

QUARTZ QUARRY

South Australia

IRON BARONCamel Hills

North Middleback

Range

(CLOSED)

WHYALLARange

IRON KNIGHT

IRON DUCHESS South MiddlebackRange


IRON DUKESpencer Gulf



HISTORY

• EARLY 1960’S - SIGNIFICANT MAGNETITE MINERALISATION INTERCEPTED AT IRON DUKE AND IRON DUCHESS

• 1967 - AN ADIT WAS DEVELOPED AT NORTH END OF IRON DUKE AND ENCOUNTERED SIGNIFICANT MAGNETITE MINERALISATIONMAGNETITE MINERALISATION

• 1989 – FIRST SERIOUS ATTEMPT TO ESTABLISH A MAGNETITE RESOURCE ~ 33 DDH, 7400M CORE, 2.5 KM STRIKE LENGTH

EARLY 2002 A REVIEW OF THE DOWNSTREAM• EARLY 2002 – A REVIEW OF THE DOWNSTREAM PROCESSING BENEFITS OF USING MAGNETITE AS FEED TO THE WHYALLA STEELWORKS LEADS TO THE CURRENT WORK BEING UNDERTAKEN


CURRENT WORK BEING UNDERTAKEN

REGIONAL SETTING


TRADITIONAL MIDDLEBACK SUBGROUP STRATIGRAGHYTRADITIONAL MIDDLEBACK SUBGROUP STRATIGRAGHY

Oxide Facies

Silicate Facies

THIC

K Upper Middleback Jaspilite

CarbonateFacies

500

m

T

Cook Gap Schist

OxideFaciesPR

OX.

2 Cook Gap Schist

Facies

SilicateFacies

Carbonate

APP

Lower Middleback JaspiliteFacies

Sulfide UnitKatunga DolomiteBasal SchistE


1000

m TH

ICK Basal Schist

Warrow Quartzite

IRO

N O

RE

MINE SEQUENCE STRATIGRAPHYCook Gap Schist

Sheared contact

Jaspilite

Magnetite silica MTS

JAS

Magnetite talc

Talc schist and other various talc, magnetite, chlorite & quartz schists

(Lower)Middleback

Iron Formation

MTT

MTSMTT

Hematite-magnetitecarbonate

Magnetite carbonateIron Formation

HMO

MTC

MTCHematite Ore

Basal Seq ence

Hematite Carbonate

BSQ

HEO

HEC

MTC

HEO

BSQ BSQ

Sulphide unit

Basal Sequence

Katunga Dolomitewith intercalated volcanics

BSQ

++++ ++

SBX

DOM


Sleaford Complex ++ ++++++++++ ++ ++

++ ++++++

++++

++++ ++

++++++

++++ ++Lincoln Complex

1500

Regional Deformation HistoryRegional Deformation History

AK

AN

EV

ENT 1500

Broad Cross Folding on E - W AxisNW - SE FaultingD4

WA

TA

East - West Compression.

1540

1710p

Broad Regional Folding, Variable PlungesUpper Green Schist FaciesP - T 1.5 - 2 Kb 450 - 525 o C

1745

D3

Major Mylonite Development

East - West CompressionTight Isoclinal FoldingA

N

OR

OG

ENY 1745

D2g g

Upper Amphibolite FaciesP - t 5 - 7 Kb 600 - 675 o C

KIM

BA

1795


Early Layer Parallel Schistosity

1845

D1

STRUCTURAL INFLUENCED2 - D2 folding is the major influence on the geometry and

distribution of mineralised host lithologies. The main controlling feature appears to be a large scale parasiticcontrolling feature appears to be a large scale parasitic syncline-anticline pair, which occurs on the west-limb of a much larger syncline.• Thickening in fold hinges is indicated at outcrop scale• Thickening in fold hinges is indicated at outcrop scale

• D3 -Main influence of D3 is the development of regional myolinite and local shear zones which bound the deposit on both sidesboth sides.

• D4 – NNW NW NE AND NNE faults are present


Section @ 16575N


MINERALISATION STYLES• Selective replacement of layers at all scales from

laminae to beds

• Pervasive replacement of layers at all scales from laminae to beds

• Matrix to breccias and clasts within breccias

• Open space filling in fractured carbonate, bedding-parting and any other odd cracks and openings

Di i t d d tt i li ti• Disseminated and spotty mineralisation

• Poorly developed stockwork veining


MINERALISATION• STRATABOUND – MTC-MTS W/MTT AT BOUNDARYS OUN C S W/ OUN

• WITH HIGH GRADE POLYMICT MATRIX SUPPORTED BRECCIAS – MATRIX OF MASSIVE MAGNETITE

•MULTIPLE STYLES

•SPATIAL ASSOCIATION W/ AMPHIBOLITE DYKES ON EASTERN SIDE OF DEPOSITEASTERN SIDE OF DEPOSIT

•FEEDER ZONES?

INTERPRETATION

• HYDROTHERMAL-METASOMATIC SEDIMENTARY CARBONATE REPLACEMENT DEPOSIT

•IN ASSOCIATION WITH GRANITIC INTRUSION?

•IN ASSOCIATION WITH METAMORPHISM?

SKARN STYLE OF MINERALISATION?


•SKARN STYLE OF MINERALISATION?

•LITHOLOGICAL FACIES CONTROL ON MINERALISATION

BRECCIA AND CARBONATE VEIN


Massive Magnetite in MTC


Breccia with Massive Magnetite


GRADE DISTRIBUTION

%SiO2 MASS REC MAG FE%SiO2 MASS REC

Target Concentrate – 69.5% Fe, 1.8% SiO2


Magnetite Magnetite Resources and ReservesResources and Reserves

Resources

Iron Magnet – 234 Mt at >37% IronIron Magnet 234 Mt at 37% Iron

Reserves

Iron Magnet 72 2Mt @ >43% Iron Iron Magnet – 72.2Mt @ >43% Iron


Project Magnet – In Fill Drilling


Phase 3 Drill Out Programme 26,000m RC

GEOPHYSICS AT IRON MAGNET CONTROLLED GEOPHYSICAL DATA CAN BE

USED TO ACCURATELY MEASURE MAGNETITE DISTRIBUTION AND CONTENT AT

DEPOSIT SCALE DRILLHOLE SCALE BLASTHOLE SCALE BLASTHOLE SCALE

INTERPRETED RESOURCE FIGURE FROM GROUND MAGNETICS


CALCULATION OF MAGNETITE CONTENT FROM DOWNHOLE & CORE PETROPHYSICS

DETAILED GRAVITY & GROUND MAGNETICS WERE ACQUIRED OVER THE MIDDLEBACK RANGES IN 1997

PROFILES OF GROUNDPROFILES OF GROUND MAGNETIC INTENSITY ON

10 x 150 METRE GRID

MAX. ANOMALY ~ 25,000 nTMAX. ANOMALY 25,000 nT

Mines Presentation - Jan 2004 400 METRES

INTERPRETATION ON 100m SECTIONS INCLUDED ALL AVAILABLE ASSAY DATA FROM HISTORICAL DRILLING

OBSERVED GRAVITY IRON MAGNETOBSERVED GRAVITY

CALCULATED GRAVITY9

mG

al

IRON MAGNET

SECTION 6316400N

OBSERVED MAGNETICS

CALCULATED MAGNETICS00

0 n

T

CALCULATED MAGNETICS

10

,0e

tre

s

SCH

HEMATITE ORE

AMPH

50

0 M

e

COOKS

“BASEMENT” HMO

MHO

INTERPRETED MAGNETITE


COOKS

RANGEUNDIFFERENTIATED

MIDDLEBACKS

ORE SHOWN IN PURPLE

DRILLHOLE RESULTS CONSISTENT WITH GEOPHYSICAL INTERPRETATION (VERY FEW ‘WASTED’ DRILLHOLES)

15 000 METRES OF DRILLING15,000 METRES OF DRILLING

HEMATITE

ORE

AMPH

SCHHMO

MHO


INITIAL PRE-DRILLING GEOPHYSICAL MODEL SUGGESTED A RESOURCE OF 71 Mt > 40% mtt

North


CALCULATION OF WEIGHT % MAGNETITE FROM DOWNHOLE & CORE GEOPHYSICS

IRON MAGNETSIX REPEAT LOGS

ALL DOWNHOLE & CORE MEASUREMENTS OF DENSITY & MAG SUSC SUBJECT TO

DD03IM009CALIBRATIONS

19-AUG-200303-NOV-200310-JAN-200417-JAN-200424-FEB-200405-MAR-04

SIX REPEAT LOGS OF CALIBRATION HOLE 150-200m

MAG SUSC (SI)

& MAG SUSC. SUBJECT TO QUALITY CONTROL 150

155

0.0 0.5 1.0 1.5 2.0 2.5

MAGNETIC SUSCEPTIBILITY (SI)0 2.5

DEFINED PROCEDURES DUPLICATES (i.e. REPEAT

READINGS) STANDARDS (i CALIBRATION

160

165

STANDARDS (i.e. CALIBRATION HOLES & STANDARDS)

ALL DOWNHOLE LOGGING COMPLETED WITH SAME VEHICLE

170

175

180COMPLETED WITH SAME VEHICLE & PROBES

ALL QC DATA VERIFIED, DOCUMENTED & STORED IN

80

185

190


READILY RETRIEVABLE FORMAT TO SATISFY AUDIT TRAIL

195

200

PETROPHYSICS DATA FROM FIRST 20 DRILLHOLES PLOTTED AGAINST DTR MAGNETITE CONTENT TO ESTABLISH CORRELATION EQUATIONS

CORRELATION USING DOWNHOLE DATA IN RC HOLESCONTROLLED & FILTERED DATA

70 n = 227TY

50

60

n = 227R2 = 0.910

y = 4.8x2 + 31.2x

R &

DE

NS

IT

40

50

ME

% M

ttE

FR

OM

DT

R

20

30

VOLU

MA

GN

ET

ITE

0

10

VO

LUM

E %


0.0 0.5 1.0 1.5 2.0 2.5SUSCEPTIBILITY (SI)SUSCEPTIBILITY PROBE RESPONSE (SI)

V

SUMMARY GRAPH OF ALL PARAMETERS RELEVANT TO CALCULATION OF MAGNETITE CONTENT

RELATIONSHIP BETWEEN DEVICE RESPONSE, TRUE SUSCEPTIBILITY AND PERCENT MAGNETITE FOR IRON MAGNET LITHOLOGIES

4.0 100Device response in this region

3.2

3.6I)

80

90

E

Device response in this region >2.5 SI - Uncontrolled data

2.0

2.4

2.8

SPO

NSE

(S

50

60

70

MA

GN

ETIT

E

1.2

1.6

2.0

DEV

ICE

RES

30

40

50

PER

CEN

T

Susc Probe in NQ hole Susc Probe in RC hole

GMS2 t C

0 0

0.4

0.8

0

10

20 GMS2 meter on Core

Volume % Magnetite Weight % Magnetite


0.00 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

TRUE SUSCEPTIBILITY (SI)

0

CALCULATION OF WEIGHT % MAGNETITE CALCULATED FROM DOWNHOLE & CORE PETROPHYSICS COMPARED WITH DTR

GRAPH SHOWS, FROMLEFT TO RIGHT :1. CALIPER.2 DENSITY

ONESTEELIRON MAGNET

DD03IM001

0 4 8 12 16 20

CALIPER Cm

ONESTEELIRON MAGNET

DD03IM001

0 1 2 3 4 5

DENSITY GM/ccDENSITY VALIDATEDAGAINST CALIPER

CORE DENSITY

ONESTEELIRON MAGNET

DD03IM001

0 0 0 5 1 0 1 5 2 0 2 5

SUSCEPTIBILITY SISUSCEPT.(CORE) SI

ONESTEELIRON MAGNET

DD03IM001CALCULATED WT % Mtt FROM DOWNHOLE DATACALCULATED WT % Mtt

FROM CORE DATA

0 20 40 60 80 100

DTR MASS RECOVERY %

2. DENSITY.3. SUSCEPTIBILITY.4. WEIGHT % MAGNETITE.

0

20

40

0 4 8 12 16 20 0 1 2 3 4 5 0.0 0.5 1.0 1.5 2.0 2.50

20

40

0 20 40 60 80 100

DATA IN UPPER PARTOF HOLE FROM DOWNHOLELOGGING.

60

80

60

80

DATA IN LOWER PARTOF HOLE FROM COREMEASUREMENTS.

100

120

100

120

CALCULATED % Mtt FROMGEOPHYSICS (RED) SHOWS

140

160

180

140

160

180


GEOPHYSICS (RED) SHOWSEXCELLENT CORRELATIONWITH DTR (BLUE).

200

220

200

220

WHAT DOES IT ALL MEAN ? FINE-TUNING GEOPHYSICAL MODEL POST-DRILLING

SUGGESTS RESOURCE OF 70 Mt > 40% MAGNETITE, COMPARED WITH JORC INFERRED STATUS OF 64 MtCOMPARED WITH JORC INFERRED STATUS OF 64 Mt.

ANY SUSCEPTIBILITY MEASUREMENT ON ANY SAMPLE TYPE CAN BE QUICKLY & ACCURATELYSAMPLE TYPE CAN BE QUICKLY & ACCURATELY CONVERTED TO A VOLUME (OR WEIGHT) PERCENT MAGNETITE.

SIGNIFICANT SAVINGS TO DATE THROUGH OPTIMISING DRILLHOLE TARGETING.

TECHNOLOGY & PROCEDURES CAN BE ADAPTED TO BLASTHOLE LOGGING TO AUGMENT GRADE CONTROL – SUBSTANTIAL SAVINGS OVER LIFE-OF-MINE OPERATIONS


MINE OPERATIONS.

GEOPHYSICS AT IRON MAGNET

ADDING VALUE

WITH ZEROWITH ZERO SAFETY,

ENVIRONMENTAL OR CULTURALOR CULTURAL

INCIDENTS, INCURSIONS OR

BREACHES



Bedded MTT / MTO


Magnetite silica


Transgressive Replacement



Sheared Magnetite Carbonate


Documents

By: Graham Bubner Chris GaughanChris Gaughan Paul Leeverssaemc.com.au/archive/2004/04onesteel.pdf · • brief history of the development of ... of hole from downhole logging. 60