Transcript Preliminary potential-field interpretation of the Capricorn Orogen

Potential Field Interpretation of the
Capricorn Orogen
Worms, forward modelling and 3D inversion
JAMES GOODWIN
Potential Field Interpretation of the Capricorn Orogen
Purpose
• Investigate regional-scale crustal architecture
• Relationship between Pilbara/Capricorn/Yilgarn
• Compare with seismic line interpretation
Interpretation Techniques
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Image processing
Multiscale edge detection (worms)
Forward modelling
3D inversion (unconstrained)
Potential Field Interpretation of the Capricorn Orogen
Seismic line 10GA-CP1
Surface
Magnetics
Geology
RTP
Hamersley
Hamersley
Ashburton
Hamersley
Potential Field Interpretation of the Capricorn Orogen
Seismic line 10GA-CP1
• Leake Springs Metamorphics = correlative of Upper Wyloo
Group (Cawood and Tyler 2004; Sheppard et al., 2007)
Hamersley Group
Leake Springs
Metamorphics
Ashburton Fm
Edmund Group
Collier
Potential Field Interpretation of the Capricorn Orogen
Seismic line 10GA-CP1
Bouguer
Magnetics
Gravity
Gravity
Worms
Hamersley
Hamersley
Karra Well Fault
(SW dipping)
Continuation Height
56703
40502
Ashburton
Baring Downs
Fault
28930
Hamersley
20664
14760
10543
7531
5379
3842
2744
1960
Potential Field Interpretation of the Capricorn Orogen
1400
0 mGals
S
N
GRAVITY
-100 mGals
Hamersley
1000 nT
3.2 / 0.10
MAGNETICS
RTP
-1000 nT
Depth (km)
LWG
0
UWG
2.67
2.8
2.6
2.8
Bandee
30
2.6
2.7
2.7
2.9
2.7
Granite-Greenstone
2.6
Fortescue
Group
2.8
2.9
Lower Crust
2.9
2.9
Mantle
3.2
60
MAGNETIC INVERSION
GRAVITY INVERSION
Potential Field Interpretation of the Capricorn Orogen
Off line effects
Hamersley
Group
Seismic line 10GA-CP2
Surface
Gravity
Magnetics
Bouguer
Geology
Worms
Gravity
RTP
Edmund
Group
Lyons
River Fault
Moorarie
Supersuite
Collier
? contact
Durlacher
Supersuite
Durlacher
Supersuite
Cardilya
Fault
Moogie
Metamorphics
Potential Field Interpretation of the Capricorn Orogen
Leake Springs
Metamorphics
S
GRAVITY
N
Leake Springs
Metamorphics
-50 mGals
MAGNETICS RTP
2.7 / 0.05
2.6
Durlarcher
Edmund Group
2.6
2.67
2.67
2.9
2.8
2.77
500 nT
-500 nT
Moorarie
2.6
2.6
2.85
Glenburgh
Terrane
-10 mGals
UWG
2.8
2.8 / 0.02
Bandee Seismic Province
2.9
2.9
2.9
Mantle
3.2
MAGNETIC INVERSION
Edmund Group
Glenburgh Terrane
Bandee Seismic Province
GRAVITY INVERSION
Potential Field Interpretation of the Capricorn Orogen
LWG
Seismic line 10GA-CP3
Gravity
Magnetics
Bouguer
Surface
Worms
RTP
Geology
Gravity
Dalgaringa Supersuite
Narryer Terrane
Potential Field Interpretation of the Capricorn Orogen
Seismic line 10GA-CP3
10GA-CP3
BIF 74257
Potential Field Interpretation of the Capricorn Orogen
Seismic line 10GA-CP3
Potential Field Interpretation of the Capricorn Orogen
MAGNETIC
INVERSION
Narryer Terrane
Glenburgh Terrane
GRAVITY
INVERSION
Errabiddy Shear
Zone
Potential Field Interpretation of the Capricorn Orogen
Key Findings
• Forward models suggest the seismic line
interpretation is consistent with potential field data.
• Hamersley Group has the potential to extend as far
south as the Edmund Basin
• Magnetic anomalies attributed mainly to the
Hamersley Group, Leake Springs Metamorphics and
BIF 74257
• Yilgarn-Capricorn boundary is south-dipping
Potential Field Interpretation of the Capricorn Orogen