Brief presentation of a pilot study investigating the application of modern thermochronometric techniques to evaluation of post-mineralisation exhumation of orogenic gold deposits in the Austrakian Yilgarn terrane.

1. Geoffrey
Ba*
Research
Associate
Professor
ExxonMobil
Fellow
Goldilocks
and
the
Fi5h
Pillar
Exhuma9on
studies
and
their
relevance
to
orogenic
gold
explora9on
in
the
Yilgarn

2. Exhuma;on
represents
a
significant
contribu;on
to
the
development
of
discoverable
and
economically
recoverable
ore
systems
Pilot
studies
using
modern
single-­‐crystal
(U-­‐Th)/He
techniques
show
promise
Control
of
this
element
of
ore
systems
is
challenging
in
the
orogenic
gold
deposits
of
the
Yilgarn
TAKE-­‐HOME
MESSAGES

4. Metalsource
Scavengingfluid
fluidFocusing
Reactivehostsite
Exhumation

5. Kalgoorlie
mining
opera-ons
Courtesy
Newmont
Australia
Ltd

6. Orogenic
gold
deposit
styles
and
examples
from
the
Yilgarn
Craton,
a5er
Goldfarb
et
al.,
(2005)
0
5km
10km
15km
20km
100°C
10°C
200°C
300°C
400°C
500°C
BrecciaLodes
DisseminatedLodes
ShearZones
LaminatedVeins
VeinSets
Wiluna
Racetrack
Granny Smith
Mt Charlotte
Golden Mile
Lancefield
Sons of Gwalia
Great Eastern
Norseman
Frasers/Hopes Hill
Marvel Loch
Nevoria
Westonia
Griffins Find

7. Economic
Exploitability
Discoverability
Orogenic
gold
deposit
styles
and
examples
from
the
Yilgarn
Craton,
a5er
Goldfarb
et
al.,
(2005)
0
5km
10km
15km
20km
100°C
10°C
200°C
300°C
400°C
500°C
BrecciaLodes
DisseminatedLodes
ShearZones
LaminatedVeins
VeinSets
Wiluna
Racetrack
Granny Smith
Mt Charlotte
Golden Mile
Lancefield
Sons of Gwalia
Great Eastern
Norseman
Frasers/Hopes Hill
Marvel Loch
Nevoria
Westonia
Griffins Find

13. The
Goldilocks
Zone

14. The
Goldilocks
Zone
Not
too
liCle,
not
too
much

17. Diorite King
Auckland
Victor Well
Riviera
Harbour Lights
Tower Hill

18. What
do
the
differences
in
endowment
represent?
Primary
contrast
in
metallogenic
processes
Contras-ng
magnitudes
of
post-­‐mineralisa-on
exhuma-on
Lack
of
preserva-on Inadequate
exhuma-on

19. Orogenic
gold
deposit
styles
and
examples
from
the
Yilgarn
Craton,
a5er
Goldfarb
et
al.,
(2005)
Economic
Exploitability
Discoverability
Zircon (U-Th)/He
Apatite (U-Th)/He
Apatite Fission Tracks
Muscovite Ar
Biotite Ar
Zircon Fission Tracks
0
5km
10km
15km
20km
100°C
10°C
200°C
300°C
400°C
500°C
BrecciaLodes
DisseminatedLodes
ShearZones
LaminatedVeins
VeinSets
Wiluna
Racetrack
Granny Smith
Mt Charlotte
Golden Mile
Lancefield
Sons of Gwalia
Great Eastern
Norseman
Frasers/Hopes Hill
Marvel Loch
Nevoria
Westonia
Griffins Find

20. Previous
a*empt
unsuccessful
Weber,
2002
Ph.D.
thesis,
Melbourne
University

21. Previous
a*empt
unsuccessful
Weber,
2002
Ph.D.
thesis,
Melbourne
University
Technical
developments
2002
Mul9-­‐grain
aliquots
2010
Single
crystal
analysis

22. Discard
Previous
a*empt
unsuccessful
Weber,
2002
Ph.D.
thesis,
Melbourne
University
Technical
developments
2002
Mul9-­‐grain
aliquots
2010
Single
crystal
analysis

23. Zircon
(U-­‐Th)/He
age
(Ma)
3000
1500
750
0
2250

24. Zircon
(U-­‐Th)/He
age
(Ma)
3000
1500
750
0
2250
Alpha
par;cle
fluence
(1015
α/g/M.yr.)
0.1 1000100101

25. Zircon
(U-­‐Th)/He
age
(Ma)
3000
1500
750
0
2250
Alpha
par;cle
fluence
(1015
α/g/M.yr.)
0.1 1000100101

26. Conclusions

27. Quan-fying
exhuma-on
has
significant
poten-al
relevance
in
the
establishment
of
explora-on
models
for
hypogene
mineral
systems

28. Thermochronometric
constraint
is
accompanied
by
significant
technical
challenges
in
the
Australian
Archaean

29. Modern
(U-­‐Th)/He
da-ng
shows
promise
as
a
means
of
resolving
exhuma-on
history
within
the
Yilgarn
terrane,
but
technical
challenges
remain
to
be
addressed

30. Ba#
CET
Science
Day,
December
2010
For
further
comment
on
this
and
other
resource-­‐related
ques-ons,
contact
the
author
at
geoff.baS@uwa.edu.au