Kuridala

Marimo-staveleyBlock

Squirrel HillGranite

Yellow WaterholeGranite

Mt DoreGranite

Selwyn

Canningtion

MaramungeeGranite

Snake Creek Anticline

Weatherly Creek Syncline

Middle Creek Anticline

Eloise

Maronan

Fairmile

Mitakoodi Blook

Duc

kC

reek

Ant

iclin

e

TommyCreekBlock

Mt AngelayGranite

SaxbyGranite

Osborne

Mt IsaInlier

Mt Isa

50 km

o

1410 0’o

1390 0’

o

190 0’

o

210 0’

Cloncurry

N

Earnest Henry

Pil

gra

mF

ault

Zone

Cloncurry

Clo

ncu

rry

Fau

ltGranite

Tommy Creek Block

WimberuGranite

Mario-staveley BlockMarimo SlateAnswer SlateStavely Formation

Roxmere Quartzite

NarakuBatholith

Soldiers Cap Group

Kuridala Formation

Corella / Doherty Formatiion

Undefferentiated Cover Sequence-II

Late Fault

Major Folds

140 141

21

220 10 20km

Major lithological subdivisions of theEastern Fold Belt (modified fromGiles and MacCready, 1997)

Gin CreekGranite

StudyArea

44

70

00

mE

44

90

00

mE

45

10

00

mE

45

30

00

mE

45

50

00

mE

45

70

00

mE

45

90

00

mE

46

10

00

mE

46

30

00

mE

46

50

00

mE

46

70

00

mE

7580000mN

7578000mN

7576000mN

7574000mN

7572000mN

7570000mN

7568000mN7568000mN

7570000mN

7572000mN

7574000mN

7576000mN

7578000mN

7580000mN

447000m

E

44

90

00

mE

451000m

E

453000m

E

455000m

E

457000m

E

459000m

E

461000m

E

463000m

E

465000m

E

46

70

00

mE

5035 35

48

49

66

51

55

55

4141

50

50

65

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43

64

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71

82

79

73

77

Grid numbers refer to Australian Map Grid (AMG), Zone 54

SAN

DY

CR

EEK

ANITRAPROSPECT

JASPER RIDGE

CAMEL DAM

Creeks

�29

�21

�20

�45

�29

�25

�30

�15

�

35

�30

�20

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30

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28

32

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26

15

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�10

�12

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�33

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�20

�22

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�17

�15

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15

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15

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�25

37

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15

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30

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15

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�

30

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�30

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�10

�21

�20

�21

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20

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29

24

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30

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21

20

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40

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20

N=18

N=40

TOBURNHUM

OUTSTATION

TO

TO

OL

BU

CH

OM

EST

EA

D

OSBORNE MINE(~10 KM SOUTH)

Sandy Creek Domain

2L 3

n=55

2L 4

n=66

n=12

3L 4

n=153

2L 2

N=88

0/1L 2

N=80

S /S0 1

S2

S2

n=566

8%4%2%1%

S3

n=89

n=78

S4

D3 effect

Anitra Domain

n= 22

n= 19

S0/1

n= 33

n= 23

S2

n= 154

S2/4

Calculatedmean fold axis

n= 16

S3

n= 19

S4

2L 2

2L 4

n= 14

2L 3

Jasper Ridge sub-domian

n= 21

2L 5

n=11

S0/1

n= 16

S2

n= 81

S2/4

n= 9

S3

n= 15

S4

2L 2

2L 4

n=6

2L 3

Calculatedmean fold axis

n= 17

n= 17

Camel Dam sub-domain

n= 91

S3

n= 51

S4

n= 43

2L 3

n= 45

2L 4

n= 58

2L 2

S0/1

n= 59

n= 285

S2

8%4%2%1%

S2

0/1L 2

n= 23

n= 8

3L 4

D3 effect

Soldiers Cap Group

Undeformed Pegmatite

Phyllite

Amphibolite

Phanerozoic Cover

STRATIGRAPHYTN

MN6.5

0 500 1000

Meters

~N

S1

S0

~N

S0

S1

~E

S2

S3

~E

~E

S3

S2S4

~W

S3

S4

~E ~E

S4

AMG: 0452796

7572500

AMG: 0454963

7570764

AMG: 0460700

7571196

AMG: 0463251

7573111

AMG: 0457070

7570800

AMG : 0465616

7573220

AMG: 0458928

7568616

AMG : 0453711

7570587

D structures1

D , D , D structures2 3 4

Structural modelGeophysical worms (Selwyn region)

450 475 500 525 550 575 600 625 650 675 700

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

chl-ctd

chl-ctd-g

Ctd-g

ctd-g-ky

g-ky

chl-g-ky

st-g-ky

st-g

bi-g-ky

bi-g-sill

bi-sill

chl-st-g

st-ctd-g

bi-st-g

bi-st

bi-st-sil

l

KFMASHSample 8.1North of Camel Dam,Selwyn RangeAMG: 0446489mE 7593215mN

bi-and

bi-st-and

chl-bi

-stch

l-st

-ctd

chl-st

chl-ctd-and chl-bi-and

chl-and

chl-st-and

KFMASH P-T pseudosection (mu+qtz+H Oin excess) showing stable phase 2

assemblages. The rock consists of staurolite-andalusite (replaced by muscovite)-biotite schist (Al O =15.6%, MgO=1.25%, FeO=5.57%, K O=3.12%; all in 2 3 2

wt %) collected from north of the Camel Dam sub-domian. Dashed line with arrow shows possible P-T path based on the appearance and disappearance of mineral phases. Metamorphic field gradient is shown on the P-T diagram for Jasper Ridge - Camel Dam (zone-1) and Anitra and Sandy Creek domains (zone-2). Second sillimanite isograd is plotted on the diagram for zone-2 rocks. Al SiO2 5

triple pints after (H) Holdaway (1971) and (P) Pattison (1992).

oT( C)

P(k

b)

Mu+qtz

Al O+K-fe

ldspar+

HO

23

2Zone-1Camel Dam - Jasper Ridge Domain(Sample-8.1)

Zone-2Sandy Creek

Anitra domains

Field Gradient

A

KFMASH P/T Pseudosection

S2

1001mm

901mm 90

1mm901mm

901mm901mm

S3

S2

S2

S3

S2S2

S3

S4

S4S3

S4

3D successions of near-orthogonal progressive bulk inhomogeneous shortening resulting in multiple generations of folds in the Mount Isa Inlier

Sayab MohammadSchool of Earth Sciences, James Cook University, Townsville QLD 4811

447000m

E

467000m

E

7580000mN

7568000mN7568000mN

449000m

E

466000m

E

7580000mN

Anitra Domain Sandy Creek DomainJasper Ridge sub-Domain

Camel Dam sub-domain

STRUCTURE SYMBOLS

���

Dip and strike of S /S0 1

Dip and strike of S2

Dip and strike of S3

Dip and strike of S4

2L Intersection lineation 4

2L Intersection lineation 3

3L Intersection lineation 4

2L Mineral lineation2

�

North and north-northeast plunging F Antiform / Synform2

Overturned/Recumbent folds

�

0/1L Intersection lineation 2

Composite S foliation2r4

Inferred north-northeast plunging F Antiform / Synform4

in Jasper Ridge - Camel Dam Domain

Vertical composite S foliation2r4

Syn-late D3

Early-syn D3

Late D2

~20km

Anitra Domain Sandy Creek Domian

S2S /S0 1

S2S /S0 1

S3

S2S /S0 1

S3

S2S /S0 1

S3

W EJasper Ridgesub-Domian

Psammite vs pelite 4 : 6

Pelite vs psammite vs quartzite 3.6 : 4.4 : 2

Psammite vs quartzite vs psammopelite vs carbonaceous pelite 2 : 3 : 2 : 3

Integrated macro, meso and microstructural analyses of the Sandy Creek, Anitra and Jasper Ridge-Camel Dam domains (southern Eastern Fold Belt, Mount Isa Inlier) provide an understanding of their structural and metamorphic evolution during the Isan Orogeny. The study area lies north of the Osborne mine and south of the Selwyn mine and hosts structurally controlled Cu-Au prospects in Mesoproterozoic rocks. Therefore, interpreting structural geology of the ore deposits and the timing and controls on mineralization, it is important to establish how deformation is partitioned in the area. Six fabric generating events are recognized from field observations and microstructural analysis. The first deformation D is revealed by 1

outcrop scale north and south verging tight to isoclinal recumbent folds with almost east-west oriented fold axes. D is characterized by close, tight 2

to isoclinal, upright and overturned north-south and north-northeast trending folds with pervasive axial planar S foliation parallel2

to S /S . Strain during D was heterogeneously developed in the area and appears to be controlled by rheological contrast across the structural 0 1 3

domains. In the Sandy Creek and parts of the Anitra domains, where pelites dominate, D is prevalent and distinguished by the development 32

of shallow dipping S and accompanying east and west verging F folds with pronounced north and north-northeast plunging L intersection lineation. 3 3 3

Mesoscopic scale S crenulations are locally developed in the Camel Dam - Jasper Ridge Domain, where dense quartzitic and psammitic units dominate. 3

Deformation during D was intense and pervasive in the Camel Dam - Japser Ridge Domain, reactivating the pre-existing S foliation forming steep 4 2

composite S foliation (S reactivated during D ). However, S can be observed where it has been rotated by D or in low strain zones of D . In the 2/4 2 4 2 3 4

Anitra and Sandy Creek domains, D can be observed as small scale tight to isoclinal upright north-south trending F folds overprinting either S or S4 4 2 32 2

with respective to north and north-northeast plunging L or L intersection lineations. Near-orthogonal shallow D and steep D were weak events3 4 5 6

best observed in thin sections only form the Camel Dam - Jasper Ridge Domain. Detailed matrix and porphyroblast-matrix microstructural relationship are consistent with the meso- and macroscale D to D structures in the area. Field structures have been correlated with 3-dimension geophysical worms,1 5

which appears to be consistent from east to west with steep lithological boundaries and consequently showing steep structural signature deep within the crust. Based on field observations and regional correlation, it is suggested that the first generation D folds were produced by north-south directed compression1

followed by D east-west shortening, producing macro- to mesoscopic scale F folds with steep S fabric. The east-west sub-horizontal shortening continued2 2 2

during D and possible during D with sub-vertical D and D events. However, due to rheological contrast and stain heterogeneity, deformation form D to 4 6 3 5 3

D were unevenly distributed. 6

H

P

Field Photographs

Perspective view

Perspective view

Structural measurements

Sample-65

Sample-61

Sample-63

Sample-7D

Structural domains