geodynamic implications of the goma deep seismic …goma workshop 25 november 2010 geodynamic...
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GOMA Workshop 25 November 2010
Geodynamic implications of the GOMA deep seismic reflection line
(08GA-OM1)Russell Korsch1, N. Kositcin1, R. Blewett1, G.
Fraser1, G. Baines2, B. Kennett3, N. Neumann1, A. Reid4, W. Preiss4, D. Giles2,
R. Armit5 and P. Betts5
1Geoscience Australia, 2U.Adelaide, 3ANU,4GSGA, PIRSA, 5Monash U.
GOMA Workshop 25 November 2010
Seismic interpretation
Series of discrete basement crustal blocks
Speculations on the geodynamic evolution of
the region(poor geological
constraints)
GOMA Workshop 25 November 2010
GOMA seismic line – Provinces and domains
GOMA Workshop 25 November 2010
GOMA seismic and MT profiles
GOMA Workshop 25 November 2010
Time-space plot(GA’s digital PROV and
EVENTS database)
Comparison of provinces and domains
Wil Chr CP Nawa Mus War1100
2600
+MC
•Different geological histories•Different seismic reflective character
GOMA Workshop 25 November 2010
Wil Chr CP Nawa Mus War1100
2600
+MC
Key province and domain boundaries
GOMA Workshop 25 November 2010
Wilgena to Christie DomainsS N
0
6
Sec
TWT
Cedric Bore FaultWilgena Domain Christie Domain
ArckaringaHangingwall
anticline
Similar reflectivity between Wilgena and Christie DomainsBoth have late Neoarchean (Mulgathing) in upper crust One coherent block?
GOMA Workshop 25 November 2010
Karari Shear ZoneChristie - Coober Pedy boundary
GOMA Workshop 25 November 2010
Karari Shear Zone(crustal-scale structure)
S N0
6
Sec
TWT
Christie Coober Pedy Mabel Creek NawaKarari SZ Horse Camp F Box Hole Creek F
GOMA Workshop 25 November 2010
Previous seismic lines in Gawler
Craton-Curnamona Province
2008-2009Eyre Peninsula +Arrowie +Curnamona-Gawler Link
2003Olympic Dam
Curnamona -Mt Painter
Eyre Peninsula
GOMA
Curnamona -Gawler
Arrowie Basin
Olympic Dam
GOMA Workshop 25 November 2010
Kalinjala Mylonite Zone
• Middle and lower crust not tracked to the surface
• West of Kalinjala Mylonite Zone •Yeltana Seismic Province –Reflective crust • Late Neoarchean (Sleaford) at surface to west of KMZ
• East of Kalinjala Mylonite Zone•Warrakimbo Seismic Province - Much less reflectivity than to west•No Late Neoarchean at surface to east of KMZ
•Kalinjala Mylonite Zone – major crustal suture?
GOMA Workshop 25 November 2010
South NorthOlympic Dam seismic survey 2003
ODBurgoyne Burgoyne BatholithBatholith
Proterozoic crust?Archean crust?
Paleoprot crust
Elizabeth Creek Fault
GOMA Workshop 25 November 2010
Gawler-Curnamona 3D model
Kalinjala MZ
Aliena SZ
Elizabeth Creek Fault
Yeltana Seismic Province Warrakimbo Seismic Province
Yarramba Seismic Province
N
250 km
EP line
OD line
GOMA Workshop 25 November 2010
Curnamona -Mt Painter
Eyre Peninsula
GOMA
Curnamona -Gawler
Arrowie Basin
Olympic dam
Late Neoarchean(Mulgathing &
Sleaford)
Possible linkage of:
Kalinjala Mylonite ZoneElizabeth Creek Fault
Karari Shear Zone
Late reactivation?
GOMA Workshop 25 November 2010
A model for formation of proto-Kalinjala Mylonite Zone (? = proto-Karari Shear Zone)
Implies later reactivation on Kalinjala MZ and Karari SZ
GOMA Workshop 25 November 2010
Absence of 2000-1850 Ma rocks and events in GOMA region
Younger extensional basins – possible backarc environment(? arc to east to northeast)
Karari SZ?
GOMA Workshop 25 November 2010
Coober Pedy and Mabel Creek Domains
upper crust - possible north-directed (south-dipping) thrust duplex or antiformal stack between two north-dipping crustal-scale faults?younger succession thrust to north over Neoarchean?younger succession deposited on Neoarchean& detached later
GOMA Workshop 25 November 2010
Box Hole Creek Fault Mabel Creek – Nawa boundary
? Significance of Neoarchean in GOMA 4
GOMA Workshop 25 November 2010
Subdomains within Nawa Domain
GOMA Workshop 25 November 2010
Subdomains within Nawa DomainBoundaries of subdomains: north-dipping, subparallel reflections = crustal-scale faults?Nawa Domain = imbricated, crustal-scale thrust stack?Imbrication in Kimban (1740-1690 Ma) or Kararan (~1570 Ma) or Coorabie (~1450 Ma – M. Hand et al. SAREIC data)?
S NNawa Domain
GOMA Workshop 25 November 2010
Northern end of GOMA -Woodroffe ThrustMusgrave – Warumpi boundary
GOMA Workshop 25 November 2010
Musgrave to Warumpi ProvincesS N
0
6
12
17
S TWT
Amadeus
Musgrave
Warumpi
Woodroffe Thrust
Moho
GOMA Workshop 25 November 2010
Seismic Lines in central Australia
2008 GOMA
1985 Amadeus-Arunta
(2009 Georgina-Arunta)
2008
1985 2009
GOMA Workshop 25 November 2010
Traverse K
1985 Arunta-Amadeus deep seismic reflection line
GOMA Workshop 25 November 2010
Old processing
BMR85-1AS N
0
20
Sec
TWT
Warumpi Aileron
GOMA Workshop 25 November 2010
Seismic line in southern Amadeus Basin
Amadeus Basin at surfaceInferred Warumpi Province at depth
GOMA Workshop 25 November 2010
Southern end of 1985
seismic line
GOMA Workshop 25 November 2010
Cartoon – crustal architectureGawler Craton to Arunta region
GOMA Workshop 25 November 2010
Crustal units in southern Northern Territory
Source: NTGS
NAC(Aileron)
WARUMPI ??
MUSGRAVE
GOMA Workshop 25 November 2010
Sarda Bluff FaultGawler (Nawa) – Musgrave boundary
GOMA Workshop 25 November 2010
Sarda Bluff Fault
S N0
10
Sec
TWT
Sarda Bluff Fault
Mt Johns Fault
Nawa
Yoolperlunna
Musgrave Musgrave
Everard ThrustMoorilyanna
Officer Basin Musgrave Province
Possible suture between Gawler Craton and Musgrave Province?Timing: possibly Kararan Orogeny (~1570 Ma)
GOMA Workshop 25 November 2010
A model for amalgamation of Gawler-Musgrave-NAC (Arunta)
WF
?Future SBF
GOMA Workshop 25 November 2010
GOMA Workshop 25 November 2010
MUSGRAVE GAWLER(NAWA)
GOMA Workshop 25 November 2010
Yoolperlunna InlierS N
0
9
Sec
TWT
Officer
MusgraveProvince
Yoolperlunna Inlier Mt Johns F
Sarda Bluff F
Cadney Park Seismic Subdomain
Wintinna Hill SS
Wintinna Hill F
GOMA Workshop 25 November 2010
Yoolperlunna Inlier
• Yoolperlunna Inlier (Gawler affinities) backthrust to north over Musgrave Province
• Timing – after amalgamation of Nawa Domain with Musgrave Province
• But, earlier than deposition of Neoproterozoic in Officer Basin
GOMA Workshop 25 November 2010
Later events• Neoproterozoic extension
– Half grabens in Officer Basin• Petermann Orogeny, e.g.
– Everard Thrust (southern outcrop limit of Musgrave Province)
– Southern margin of Amadeus Basin (basement nappe)
• Alice Springs Orogeny, e.g.– Deformation of Moorilyanna Graben– Reactivation of Woodroffe Thrust
GOMA Workshop 25 November 2010
Lithospheric upper mantleS N
0
60
120
km
Preliminary MT model to depth of 150 km
GOMA Workshop 25 November 2010
Preliminary MT model plus seismic interpretation
Low resistivity in lithosphere below Wilgena and Christie Domains (Neoarchean at surface)Very high resistivity below Musgrave ProvinceChange in resistivity – fundamental lithospheric boundary, ?significance for mineral systems
GOMA Workshop 25 November 2010
Shear wave velocity for upper mantle(seismic tomography)
S N
Fast seismic shear-wave speeds to ~200km depth = approximate base of lithosphere
GOMA Workshop 25 November 2010
Shear wave velocity (seismic tomography) and preliminary MT model
GOMA Workshop 25 November 2010
Shear wave velocity (seismic tomography) and preliminary MT model
GOMA Workshop 25 November 2010
Summary
GOMA Workshop 25 November 2010
Conclusions
• Seismic defines several discrete crustal blocks• Speculative implications:
– Karari Shear Zone may link to southeast– Upper crust in Coober Pedy and Mabel Creek
domains possible thrust duplex or antiformal stack– Nawa Domain – several subdomains: imbricated,
crustal-scale thrust stack– Possible amalgamation of Arunta Region
(Warumpi) – Musgrave Province – Gawler Craton (Nawa)
• Paucity of geological data means more samples needed to constrain speculations (drilling!)
GOMA Workshop 25 November 2010
Seismic data available at:www.ga.gov.au/minerals/research/national/seismic/
THANK YOU
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