The National Geochemical Survey
of Australia
Patrice de Caritat
Geoscience Australia
A collaborative project under National Geoscience Agreements with
New South Wales Department of Primary Industries, Mineral Resources Tasmania,
GeoScience Victoria, Primary Industries and Resources South Australia,
Geological Survey of Western Australia, Northern Territory Geological Survey,
Geological Survey of Queensland
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Outline of Presentation
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Why geochemical surveys?
Review of pilot projects
Aims of NGSA
Strategy of NGSA
Results and preliminary interpretations
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Total element concentrations
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Weak digestion concentrations
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Visible near-infrared spectroscopy
Conclusions
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Geochemical Surveys 101
What are geochemical surveys?
• GS are the documentation of the chemical composition of the
Earth’s surface: concentration values & patterns
• Fundamental dataset
• Nature of end-product depends on a number of strategic
decisions:
 Purpose (minex, environmental, land-use, etc.)
 Size of area to cover (strategic v tactical)
 Sampling medium
 Sampling density
 Constraints: time, resources, history, etc
Gd+Sm
Ti
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Neutron
Spectrometry
Data
Elphic et al.
(1998, 2000)
Geochemical Surveys 101
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Initially developed for mineral exploration
(“geochemical prospecting”)
Reconnaissance geochemical surveys started in the
1960’s (Nichol et al., 1966)
Gained widespread popularity in many parts of the
world over ensuing decades
Variety of applications: mineral exploration,
environmental baseline, geohealth (e.g., drinking
water!), land rehabilitation, risk assessment, etc.
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Selected Results from Pilot Projects
Curnamona:
Approx area
Number of
Average sampling
(km )
sampling sites
density (1 site per
X km )
 Broken Hill region; base
metal,
Cu-Au
Curnamona
61,915
199
311
Riverina
142
866
• Riverina:122,976
Gawler
53,636
48
1117
 Agriculture,
Murray
Basin;
Au, base metal
Thomson
209,824
99
2119
• Gawler:
 Arid, flat, aeolian influence; Olympic Dam Feoxide-Cu-Au-U, Au
• Thomson:
 Eromanga/GAB Basin cover; borders on
Curnamona and Cobar (base metal, Cu, Au)
districts
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Pilot survey
2
2
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Selected Results from Pilot Projects
Riverina: Th channel airborne radiometrics vs Th (ppm) in <180 um TOS
Caritat et al., GEEA, 2008
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Selected Results from Pilot Projects
Profile 111
Fe
Zn
Profile 133
Riverina: Depth profiles
Fe
Zn
Shallow (<10 cm) and
deep (>50 cm) levels are
geochemically distinct
Caritat et al., GEEA, 2008
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Gawler: Zn (ppm) in <180 um TOS
133°0'E
133°30'E
134°0'E
134°30'E
135°0'E
135°30'E
136°0'E
136°30'E
St Peters
Suite Granite
31°30'S
31°30'S
31°0'S
31°0'S
30°30'S
30°30'S
Lower Gawler
Range Volcanics
Sleeford Complex
Glenloth Granite
Tunkillia Suite
Granite
Ifould Complex
A
32°0'S
32°0'S
I
Upper Gawler
Range Volcanics
Hiltiba Suite
Granite
Harris Greenstone
Belt Volcanics
Hutchinson Group
32°30'S
32°30'S
Lakes
00
3030
Catchment Outline
Zn (<180 um) (ppm) (TOS)
33°0'S
33°0'S
¯
Australian coastline
6060
120
120
1-8
9 - 22
133°0'E
133°30'E
134°0'E
134°30'E
135°0'E
135°30'E
136°0'E
33°30'S
23 - 30
Kilometres
Kilometres
31 - 40
41 - 63
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Caritat et al., GEEA, 2008
Grouped by size fraction:
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Frequency (%)
Cu (ppm)
Selected Results from Pilot Projects
Cu in Gawler: variation between sites >> variation
between grain sizes
Cu (ppm)
Grouped by site:
• N = 72 (6 sites x 2 depths x 6 fractions )
• Finest size fraction has significantly elevated
Cu concentrations compared to coarser
• Thus, analysing a fine and a coarse fraction
adds information
• Regardless of depth or size fractions, some sites
have significantly more elevated Cu values
• This is why low-density geochemical mapping works!
A.
<75 μm
B
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7
C
.
D
E
F
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.
-
1
8
μ
0
m
μ
m
1
8
0
-
5
0
0
5
0
0
-
1
0
0
0
1
0
0
0
2
0
0
<
.
5
1
8
0
-
μ
m
μ
0
m
μ
m
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Caritat et al., GEEA, 2008
National Geochemical Survey of Australia
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In August 2006, the Australian Government
announced support for Onshore Energy Security
Program (OESP)
$59M over 5 years (2006-2011)
Uranium, thorium, geothermal, petroleum
Geoscience Australia established a multidisciplinary program to tackle this new focus
(seismic, AEM, AWAGS2, geothermal, NGSA, etc.)
NGSA is but one of the OESP projects
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Aims of NGSA
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To provide pre-competitive data and knowledge to support
exploration for energy resources in Australia
Specifically
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To improve the existing knowledge on the concentration
and distribution of energy-related elements such as
uranium (U) and thorium (Th) at the national scale
•
But it will also provide new data for a range of commodity
related elements such as gold (Au), copper (Cu), nickel (Ni)
and zinc (Zn), among others, as well as several elements of
interest for other applications, e.g. environmental
management, at the national scale
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Strategy for NGSA
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To keep costs down, an ultra-low sampling density strategy
was adopted, backed by results from pilot projects
Transported sediment: ‘a well-mixed composite sample of
dominant lithologies upstreams’ as sampling medium
Collect a proper sediment sample (fine-grained material,
overbank/floodplain environment, outlet sediment, away from
disturbed or polluted sites)
Sample at 2 depths and separate 2 grain-size fractions to
enhance geochemical information
Analyse for major, minor & trace elements after total + aqua
regia + Mobile Metal IonTM digests
Identify areas where sediment chemistry indicates lithologies
or mineralisation of interest
Industry can focus further exploration investment in those
selected areas and save $$
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
National Geochemical Survey of Australia (NGSA)
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Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Landscape divided in
large catchments
Only mainland
Australia + Tas
Topographic analysis
to split or amalgamate
catchments
Hydrologic analysis to
determine catchment
outlets
Ignore catchments
<1000 km2 (mostly
coastal)
91% coverage
Emphasis on QA/QC
from field to reporting
National Geochemical Survey of Australia (NGSA)
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www.ga.gov.au/ngsa
Contact: Patrice.deCaritat@ga.gov.au
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Sample transported
regolith at outlets of
1186 catchments over
mainland Australia
123 of these
catchments have
been sampled in
duplicate for quality
control
6 other, large
catchments also
sampled higher up
Average density
~1 site/5200 km2
(similar to FOREGS
European Atlas)
86% of the
catchments have
been sampled
Over 6 million km2 (or
80% of Australia) has
been sampled
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
National Geochemical Survey of Australia
0-10 cm depth:
Top Outlet Sediment (TOS)
ca 60-80 cm depth:
Bottom Outlet Sediment (BOS)
www.ga.gov.au/ngsa
Air-dried, homogenised, split into
‘Bulk’, or sieved to <2 mm
(‘Coarse’) and to <75 um (‘Fine’)
grain size fractions
Analysed for TOTAL,
AQUA REGIA and
MMITM element
content
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Geology
Geology
Paleoproterozoic basins &
complexes
Mesozoic sedimentary basins
Paleozoic metamorphic &
igneous rocks
Archean cratons & basins
Neoproterozoic basins
Mesoproterozoic basins &
complexes
Cenozoic & Quaternary
sediments
Distribution of MMI™ extractable Ga (ppm) in Australia
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Validation of NGSA pH against existing datasets
Caritat et al. (2011)
Caritat et al. (2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Preliminary interpretation of NGSA results
B
C
F
G
A
D
E
H
Caritat et al. (2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Comparison airborne vs soil geochemistry
TOS U ppm vs Airborne eU ppm (300m radius average)
with > 25% 2mm fraction removed
8
R2 = 0.3319
Airborne eU ppm
7
(p<0.01)
6
5
4
3
2
1
0
0
2
4
6
8
10
12
14
Soil U ppm
Existing U channel image
‘Corrected’ U channel image
Green: 0 ppm U --- Red: 12 ppm U
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Wilford et al. (2011)
Comparison airborne vs soil geochemistry
TOS Th ppm vs Airborne eTh ppm (300m radius average)
with > 25% 2mm fraction removed
40
R2 = 0.5768
Airborne eTh ppm
35
30
25
20
15
10
5
0
0
5
10
Wilford et al. (2011)
15
20
25
30
35
40
45
Soil Th ppm
Caritat & Cooper (2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Preliminary interpretation of NGSA results
B
C
A
F
D
E
Caritat et al. (2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Possible causes of geochemical anomalies
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Horizontal/lateral dispersion from ore deposit,
mineralisation, secondary enrichment or alteration
zone
Vertical migration of chemical elements due to
processes to be determined that could include
groundwater (advection & diffusion), soil gas, plants
or micro-organisms, electro-chemical currents over
sulfide bodies or even lightning strikes
Contamination due to mining activities (e.g., dust),
but (1) sites selected away from mines, (2) anomalies
also in deeper BOS sample, (3) found equally around
open-pit and underground mines, and (4) do not
outline ore transport routes
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Preliminary interpretation of NGSA results
B
C
A
Caritat et al. (2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Preliminary interpretation of NGSA results
C
B
A
D
Caritat et al. (2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Preliminary interpretation of NGSA results
Concentration-Area (C-A) fractal analysis of Zn distribution
“Background”
“Anomalous”
Class 1 (4-9 ppm)
Class 2 (9-40 ppm)
Class 3 (40-70 ppm)
Class 4 (70-105 ppm)
Class 5 (>105 ppm)
9 mg/kg
40
72
Class 1
2
3
105
4
5
Zn deposit
Zn occurrence
Caritat et al. (2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Extraction Methods and Bio-Availability
SGS
Mann et al. (2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
MMI extractable Ba (ppm)
TM
Ba (MMI)
<0.01-0.18
0.18-0.34
0.34-0.48
0.48-0.65
0.65-0.89
0.89-1.17
1.17-1.50
1.50-2.19
2.19-3.36
3.36-15.3
Caritat et al. (2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
MMI extractable La (ppm)
TM
La (MMI)
<0.001-0.002
0.002-0.005
0.005-0.010
0.010-0.021
0.021-0.040
0.040-0.068
0.068-0.120
0.120-0.201
0.201-0.336
0.336-3.310
Caritat et al. (2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
MMI extractable Au (ppb)
TM
Au (MMI)
<0.1 ppb
<0.1-0.1
0.1-0.2
0.2-0.3
0.3-0.4
0.4-0.5
0.5-0.7
0.7-0.9
0.9-1.3
1.3-1.98
Telfer
Meekatharra
Coyote
The Granites
Ernest Henry
JundeeNimary
Osborne
Plutonic
Sarsfield
Vera Nancy
Mt Rawdon
Golden Grove
Sons of Gwalia
Agnew, Thunderbox,
Hill 50, Lalwers, Granny
Smith, Darlot-Centenary
Marvel Loch,
Bullfinch
The Peak, Tritton,
Endeavor, North Parkes
Prominent Hill
Olympic Dam
Bounty, Frog’s Leg,
Broken Hill
Norseman, Kundana
Roseberry
Primarily Au Mine
Primarily Cu or Zn Mine
Caritat et al. (2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Cowal, Peak Hill,
Ridgeway, Cadia
Stawell, Fosterville
Average % Bioavailability
MMI/Total: A measure of bio-availability?
N GSA Overbank Sampling
16
14
12
10
8
% Bioav ailability
6
4
2
0
C a C u Fe
Mann et al. (2011)
K
Mg Mn
P
Zn
Bas ed on 1190 Comparis ons MMI vs T otal Analys is for Ca, Fe, P
1176 for Cu, 1188 for K, 1161 for Mg, 1138 for Mn, 1169 for Zn
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
-10
-15
800
-20
600
Arid Zone
-25
Limestone
Lithology
-30
400
200
-35
Nullarbor Plain
(limestone)
0
-40
Ca
-45
110
115
MMI Ca(ppm)
120
125
130
135
140
145
150
155
NGSA Overbank Sampling
Isotropic Kriging MMI Image
Geoscience Australia - SGS
Mann et al. (2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
. Overbank
Sampling
Location
-10
-15
200
-20
150
-25
Arid Zone
and/or
Salt lakes
-30
100
50
-35
0
-40
K
-45
110
MMI K(ppm)
115
120
125
130
135
140
145
150
NGSA Overbank Sampling
Isotropic Kriging MMI Image
Geoscience Australia - SGS
Mann et al. (2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
155
. Overbank
Sampling
Location
-10
-15
8
-20
6
-25
4
-30
2
-35
High
Rainfall
Zones
c.f. Fe
-40
Mn
-45
110
115
120
125
130
0
MMI Mn(ppm)
135
140
145
150
155
NGSA Overbank Sampling
Isotropic Kriging MMI Image
Geoscience Australia - SGS
Mann et al. (2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
. Overbank
Sampling
Location
Vis-NIR Spectroscopy
Viscarra-Rossel et al. (2010,2011)
PC1
Variance
PC1: hematite (-);
2:1 clay minerals (+)
PC2
Variance
PC2: SOM, smectite (-);
kaolinite (+)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
PC3
Variance
PC3: illite, smectite,
goethite? (-); SOM (+)
Vis-NIR Spectroscopy
Viscarra-Rossel et al. (2010,2011)
4
1
1
2
2
kao
hem
1
3
2
SOM
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
kao
2:1 c
4
2:1 c
2:1 c
4
PC clusters 1 (orange), 2 (red), 3 (blue) and 4 (green)
with central composition (stars) and average
reflectance and continuum-removed spectra (right)
2:1 c
3
2:1 c
goe
3
Vis-NIR Spectroscopy
Australian Soil Classification:
Map of Soil Orders (Isbell 1996)
4
3
1
2
Distribution of PC clusters 1 (orange), 2 (red),
3 (blue) and 4 (green) and comparison
to Map of Soil Orders (right)
Viscarra-Rossel et al. (2010,2011)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Vis-NIR Spectroscopy
Normalised Iron Oxide Difference Index (NIODI):
Red = hematite; Yellow = goethite probability
Map of “true colour” RGB composite
of Australian topsoil
Viscarra-Rossel et al. (2010,2011)
NIODI uncertainty
map (right)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Conclusions
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Geochemical surveys provide a fundamental dataset
for decision making
Low to ultra-low density geochemical surveys yield
data that makes geological sense
Pilot projects in the Riverina, Gawler and Thomson
areas provided proof-of-concept for the NGSA
The Onshore Energy Security Program from the
Australian Government provided the financial support
for the NGSA
From 2007 to 2011, field work was carried out, sample
preparation and analysis took place, and map
production was completed
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Conclusions
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A new national geochemical dataset is available
Comparison with independent datasets indicates
reliability
Data quality assessed in dedicated report
NGSA data identifies a number of areas that may
have potential for discovery, e.g. in terms of U, Th,
Au, Pb, Zn, REEs as shown here
>500 geochemical maps available on website
www.ga.gov.au/ngsa
The dataset and atlas are useful pre-competitive
assets in the exploration for energy and mineral
resources
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)
Acknowledgments
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Australian Government for OESP funding
All States and Northern Territory for entering a National Geoscience Agreement
Land owners for access to sampling sites
Field sampling teams from State/NT geoscience agencies:
 Gary Burton, Paul Flitcroft, Trevor Hegvold (NSW)
 Andrew Wygralak, Darren Bowbridge, Simon Fanning, Rod Maier, Clarke Petrick (NT)
 Joseph Tang, Phil Boyle, Stanley Briggs, Dominic Brown, Philip Burrows, Leonard Cranfield,
Terry Denaro, Glenys Diprose, Courteney Dhnaram, Melanie Fitzell, Dudley Fulton, Janice
Harley, Jimmy Lam, Mark Livingstone, David McIntyre, Jack Skinner, Jack Ryle (Qld)
 Roger Fidler, Katherine Brownlie, Stacey Curtis, Tania Dhu, Adrian Fabris, Claire Fricke,
Georgina Gordon, Tiphaine Lavigne, Josine Parsons, Steve Sutton, Antony Whiting, Tania
Wilson, Ben Uppill (SA)
 Geoff Green, Shane Heawood (Tas)
 Emily House, Ken Sherry, Rachel Roberts (Vic)
 Colin Strickland, Richard Langford, Paul Morris, Amanda Thomson (WA)
Sample preparation and analysis team:
 Christian Thun, Liz Webber, Bill Pappas, Matthew Brown, Jessica Byass, Nounou
Chanthapanya, John Furlonger, Amber Green, Keith Henderson, Zia Husain, Bozana
Krsteska, Benjamin Linehan, Andris Lukss, Ador Makuei, Lucy McCabe, Gregory O’Connell,
Billie Poignand, Mike Smith, Helen Tait, Kylia Wall, Tony Watson (GA)
For assistance and collaboration on various aspects:
 Michelle Cooper, Evgeniy Bastrakov, Lindsay Highet, Subhash Jaireth, Megan Lech, Dan
McIlroy, Andrew McPherson, Donna Phillips, Lara Sedgmen, John Wilford (GA); John
Greenfield, John Watkins (GSNSW); Martin Fairclough (PIRSA); Paul McDonald, Adele
Seymon (GSV); Janet Stein, Mike Hutchinson, Peter Veth (ANU); Clemens Reimann (NGU);
Rudi Dutter (VUT); Alan Mann (Consultant); Pierrette Prince (SGS); Raphael Viscarra-Rossel
(CSIRO); Eric Grunsky (GSC)
Geochemical Atlas of Cyprus Symposium (Lefkosia, Cyprus, 5-7 Sep 2011)