Dating of the Hiltaba-GRV event and associated mineral systems

Dating of the Hiltaba-GRV event
and associated mineral systems
Elizabeth Jagodzinski
11th August 2016, Mineral Systems Drilling Program Open Day
Dating of the Hiltaba-GRV event
and associated mineral systems
1. Recent high-precision TIMS dating of the
Hiltaba-GRV thermal event
2. Dating of Olympic Dam and other IOCG deposits
3. Dating of Hiltaba-associated mineral systems on the
southern margin of the Gawler Range Volcanics
4. Dating of the MSDP holes and future directions.
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Gawler Range Volcanics & Benagerie Volcanic Suite SLIP
estimated volume ~ 100 000 km3
~ 70 000 km3 GRV, ~ 30 000 km3 Hiltaba
+ BVS in Curnamona Province
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Gawler Range Volcanics & Benagerie Volcanic Suite SLIP
• 25 000 km2 of GRV exposed in the
central Gawler Craton.
• Evolution of the GRV is separated into
two main stages:
• lower GRV 1591 ± 3 Ma
• upper GRV 1592 ± 3 Ma
• BVS correlated with the upper GRV
1584–1587 ± 6 Ma
• Hiltaba Suite ~ 1595–1575 Ma
with some indication of spatial-temporal
variation, with the oldest Hiltaba Suite
occurring in the OD region
Fanning et al. Precambrian Research 40-41 (1988) 363 – 386
Wade et al. Precambrian Res. 206–207 (2014) 17-35
Jagodzinski (2014 AESC)
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lower GRV
Lavas from 1 km3
to 150–200 km3
Myall Creek
~ 2.4 Km
Roopena
~ 500 m
Glyde Hill >1km
Chitanilga
Agangi (2011) PhD Thesis CODES
S.R. Allen et al. JVGR 172 (2008) 132–147
McAvaney & Wade (2015) DSD RB 2015/00021
5
Menninnie Dam
~ 3km
~ 200 m
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Lavas are an order of magnitude bigger than lower GRV units
200-300 m thick
600–2400 km3
upper GRV
6
S.R. Allen et al. Australian Journal of Earth Sciences 50:1 (2003) 97-112
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Ca-TIMS Results
 Concordia diagrams
Benagerie Volcanic Suite
Age Ma
error 2σ
2049213
Finlay Dam Rhyolite
1587.3
0.5
2049215
Finlay Dam Rhyolite
1588.2
0.6
Upper Gawler Range Volcanics
1998160
Moonaree Dacite Member
1587.2
0.5
1998158
Eucarro Rhyolite
1587.5
0.6
Lower Gawler Range Volcanics, central Gawler Craton
1998163
Mangaroongah Dacite
1587.7
0.6
2018616
Bittali Rhyolite
1589.3
0.5
2016125
Ealbara Rhyolite
1591.2
0.5
Gawler Range Volcanics, Stuart Shelf
2000366166
Felsic dyke Olympic Dam
1593.0
0.5
2131365
undifferentiated, Red Dam
1593.6
0.4
2131354
undifferentiated, SAE 11
1595.4
0.6
7
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Ca-TIMS Results
 Ranked date plot
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8
Ca-TIMS Results
 The duration of volcanism in the GRV-BVS SLIP was ~ 8 Myr
 The extensive upper GRV lavas erupted instantaneously, in ≤ 1 Myr,
possibly from large fissures.
 The BVS in the Curnamona is temporally equivalent to the upper GRV
 There is significant age variance in the lower GRV, indicating
each small volcanic centre represents a discrete temporal event
 The oldest zircons are from the Olympic Dam region, where the GRV
extends below the Stuart Shelf to the east (Olympic Domain)
 The Mangaroonah Dacite from the lower GRV (Glyde Hill Volcanic Complex)
is the same age as the upper GRV lavas, suggesting ‘lower GRV- style’
volcanic centres continued erupting into upper GRV time
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CFBPs: a modern analogue
3 eruptive phases
 The time span, eruptive history and volcanic facies of GRV are analogous with CFBPs
1.
Initial phase: low volume eruptions from spatially scattered
volcanic centres. Location controlled by pre-existing crustal
weaknesses ≡ lower GRV ~ 8 Myr
2.
Main phase: repeated large volume eruptions of extensive
tabular tholeiitic flows, and in some cases silicic magma, from
a number of spatially restricted eruption sites and fissures
≡ upper GRV ~ 1 Myr
3.
Waning phase: usually more protracted, decrease in eruption
volume, longer hiatuses between eruptions, increasing silica
content and explosive eruptions, more widely distributed or shifts
in locus of magmatism ? ≡ ongoing Hiltaba intrusion* ~ 10 Myr
5–10 Myr
* The Hiltaba granites intruded co-evilly with GRV, and
continued intruding post-eruption, until ~ 1575 Ma
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1 Myr
10
CFBPs: a modern analogue
CFBPs
Initial phase 5–10 Myr
≡ lower GRV
~ 8 Myr
Main phase ~ 1 Myr
≡ upper GRV
~ 1 Myr
≡ ? Hiltaba
?10 Myr
Waning phase
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GRV
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Future directions
Chandabook
a
Dacite
Roopena MSDP01
 Wheepool Rhyolite, Glyde Hill
Lake
Gairner
Rhyolite
 Chitanilga Volcanic Complex
Wheepo
ol
Rhyolite
 Angle Dam Volcanics at Roopena
 MSDP holes, southern Gawler Ranges
Glyde Hill
Wheepool
Chitanilga
Mangaroongah
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Angle Dam
Volcanics
 Relationship between Roxby Downs
Granite/Hiltaba and GRV at Olympic
Dam: intrusive? unconformity?
Future directions
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OLYMPIC DAM
Host Rocks
 pitchbende maximum crystallisation
~1400 Ma, about 200 m.y. younger
than the Roxby Downs Granite
(Trueman 1986)
 ODBC, alteration and mineralisation
~1590 Ma, associated with the GRVHiltaba thermal event (Johnson and
Cross 1995)
 CODES dating of sulphide phases
(galenas), preliminary interpretations
1200-1400 Ma (Meffre et al., 2010
GODs conference)
Jagodzinski (2014 AESC)
Department of State Development
Timing of mineralization in
Olympic Cu-Au Province
Manxman West: 1567 ± 10 Ma (titanate, U-Pb)
Prominent Hill: 1585 ± 8 Ma (zircon, U-Pb)
Vulcan: 1586 ± 8 Ma (molybdenite, Re-Os)
Olympic Dam: 1572 ± 99 Ma (sulphides, Sm-Nd)
~ 1400 Ma
(pitchblende, U-Pb)
1258 ± 28 Ma (sulphides, Re-Os)
Acropolis: 1604 ± 9 Ma (apatite, U-Pb)
Torrens: 1575 ± 11 Ma (muscovite Ar-Ar)
Murdie: 1576 ± 5 Ma (titanate, U-Pb)
Oak Dam: 1455 ± 20 Ma (monazite, U-Pb)
Punt Hill: 1577 ± 5 Ma (garnet-diopside, Sm-Nd)
Hillside: 1584 ± 6 Ma (titanite, U-Pb)
Moonta-: 1599 ± 6 Ma (molybdenite, Re-Os)
Wallaroo 1577 ± 6 Ma (molybdenite, Re-Os)
1574 ± 6 Ma (molybdenite, Re-Os)
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Reid et al. Economic Geology 108 (2011) 883–894
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OLYMPIC DAM
 hydrothermal zircon ~ 1690 Ma, with Musgravian–Delamerian
resetting/remobilisation (Jagodzinski 2014)
 hematites 1577 ± 5 Ma, 1590 ± 8 Ma, (Ciobanu et al., 2013)
 BHP-Billeton-CODES concur that the mineral system is
co-eval with the GRV and associated Hiltaba Suite, and is a
multi-stage, prolonged hydrothermal system evolving
progressively over ~1.0 Ga, in response to major
tectonothermal events
 1600 Ma breakup of Columbia Supercontinent
 1400 Ma final cratonisation, rebrecciation
and incorporation of Pandurra Fm
 1.3 -1.1 Ga Rodinia assembly
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
825 Ma Ga breakup of Rodinia
 500 Ma Delamerian Orogeny –Gondwana
assembly
Timing of mineralization in other Hiltaba-GRV-related prospects
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Timing of mineralization in other Hiltaba-GRV-related prospects
Mawson
Host rock is c. 1790–1740 Ma Cleve Group : quartz-feldspar-sillimanite gneiss Dmax c. 1740 Ma
Kimban metamorphism (titanite in amphibolite) 1718 ± 6 Ma
Kimban intrusion (leucogranite) c. 1685 Ma
Skarn alteration 1581 ± 9 Ma (Sm-Nd)
1604–1548 Ma (Re-Os)
Weednana
•
•
•
•
•
Hiltaba granite intruding host gneisses 1584 ± 5 Ma
Telephone Dam base metal Pb-Zn
•
Host rock is Sleaford Complex:
leucocratic felsic gneiss Dmax 2473 ± 8 Ma
Menninnie Dam Pb-Zn
•
Basement to metasedimentary host sequence:
Sleaford Complex biotite-rich gneiss 2511 ± 4 Ma
Paris epithermal Ag-Au
•
Monzogranite porphyry 1593 ± 8 Ma
•
Rhyodacite feeder dyke 1597 ± 14 Ma
18
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Future directions MSDP holes
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Future directions MSDP holes
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Disclaimer
The information contained in this presentation has been compiled by the Department of State
Development (DSD) and originates from a variety of sources. Although all reasonable care has been
taken in the preparation and compilation of the information, it has been provided in good faith for
general information only and does not purport to be professional advice. No warranty, express or
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Acknowledgements
Our study stands on the shoulders of giants and we have built on the contributions of earlier
workers in the GRV, particularly the CODES team at U.Tas and their studies of the physical
volcanology. Thanks to Jocelyn McPhie for giving me carte blanche to use diagrams from
their many publications. And to Kathy Ehrig, our collaborator at BHP Billiton, for permission
to refer to unreleased TIMs dates from Olympic Dam.
This study has been submitted to the J.Geol.Soc.Lond. for publication.
Contact
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