Deep crustal architecture as a context for mineral discovery in the Curnamona. Stephan Thiel

Geological Survey of South Australia

Broken Hill Symposium, 27th May 2015

www.statedevelopment.sa.gov.au

UNCOVER – template for mineral exploration

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1.  Characterising the cover

2.  Australia’s whole lithosphere architecture

3.  4D geodynamic and metallogenic evolution

4.  Characterising and detecting distal footprints  

Themes Scale

Continental scale

Regional scale

Camp scale

Deposit scale

MT images from a few tens of meters to hundreds of kilometers

Exploration across scales

3 Department of State Development Groves & Santosh, 2015, GF Griffin et al., 2013, Nature Geoscience

Plume interaction with cratonic setting Generalised convergent margin settings

Fast vs slow mantle lithosphere

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Geodynamic model of the Tasmanides

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Moresi  et  al.,  2014  Nature  

Rawlinson  et  al.,  2014  Geology  

Seismic  anisotropy    due  to  slab  roll  back  

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Broken  Hill    

Kate  Robertson,  U  of  A  

Geophysical observables from the Gawler into Curnamona

Seismic reflection

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Flinders AusLAMP MT

8 Department of State Development Kate  Robertson,  U  of  Adelaide  

Regional MT geotransects

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Peter  Milligan,  GA  

Role of deep fluids in mineral genesis – reducing agent?

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Example of high-resolution (1 km) MT survey across Beverley U-mine

Is electrical resistivity a proxy for strain and metamorphism?

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Thiel  et  al.,  in  prep  

Extension  

Compression  1  

Present  compression  

Celerier  et  al.,  2005,  Tectonics  

Terrane scale exploration - AusLAMP SA 50km grid

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AusLAMP extension – University of Adelaide

3D inversion 88 sites included in modelling with emphasis on data quality: •  Red – new AusLAMP

sites •  Blue – legacy long-

period MT sites •  Open – yet to be

collected and included in modelling

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3D resistivity models

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Mantle fertilisation beneath the Gawler

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Rawlinson  et  al,  2014,  Lithos  

Terrane-scale

AusLAMP  SA  MT    

Mantle-crust connection beneath Stuart Shelf

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rox0

00

RO

X001

RO

X003

RO

X005

RO

X006

rox0

07

RO

X009

RO

X011

RO

X012

RO

X013

RO

X014

rox0

15ro

x016

RO

X017

RO

X018

RO

X019

RO

X020

RO

X021

RO

X022

RO

X023

RO

X024

RO

X025

RO

X026

RO

X027

rox0

29

RO

X031

RO

X033

RO

X035

RO

X037

rox0

38

OD

01O

D02

OD

03O

D04

OD

05O

D06

OD

07O

D08

OD

09O

D10

OD

12O

D14

OD

15O

D16

OD

17O

D18

OD

19O

D20

OD

22O

D23

OD

24O

D25

OD

26O

D27

OD

28O

D29

OD

30O

D31

OD

32O

D34

OD

35O

D38

OD

40O

D41

OD

42O

D43

OD

44O

D45

OD

46O

D47

OD

48O

D49

OD

50O

D52

OD

53O

D54

OD

55O

D56

OD

57O

D58

OD

59O

D60

OD

61O

D62

OD

63O

D64

OD

65O

D66

OD

67O

D68

OD

69O

D70

OD

71O

D72

OD

74O

D75

OD

76O

D78

OD

79O

D80

20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200

0-10000-20000-30000-40000-50000-60000-70000-80000-90000

-100000-110000-120000-130000-140000-150000-160000-170000-180000

0-10000-20000-30000-40000-50000-60000-70000-80000-90000

-100000-110000-120000-130000-140000-150000-160000-170000-180000

Distance (Km)

Dept

h (m

)

1000

794

631

501

398

316

251

200

158

126

100

79

63

50

40

32

25

20

16

13

10

8

6

5

4

3

3

2

2

1

1

Ohm.m

Updated from Heinson et al., 2006

Regional-scale

Archaean core

Archaean core

Olympic Dam

Conclusions

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•  AusLAMP SA will highlight the terrane to regional lithospheric architecture of the state

•  Show fluid related metasomatism events (mantle) and fluid pathways (crust) conducive to “fertility corridors”

•  MT needs better integration and analysis with reflection and passive seismic arrays with petrophysical constraints

•  Fluid pathways appear structurally controlled and governed by geodynamic controls (stress, rheology)

•  Future targeted camp-scale MT and other geophysical surveys will greatly benefit from the lithospheric architecture provided through AusLAMP SA

Stephan Thiel

www.statedevelopment.sa.gov.au

Department of State Development Level 4, 101 Grenfell Street Adelaide, South Australia 5000 GPO Box 320 Adelaide, South Australia 5001

T: +61 8 8204 1181 E: stephan.thiel@sa.gov.au

Acknowledgement •  Philippa Mawby, Bruce Goleby and Geoff Axford (AusLAMP core field crew, University

of Adelaide), numerous students for field work •  Katherine Betschart, Ian Hopton and David Love (DSD) for liaison and access •  AARD for Aboriginal liaison •  WPA, National Parks SA, traditional owners and numerous pastoralists for land

access •  AuScope MT equipment pool