New zircon and monazite geochronology from recent GOMA Drilling · 2015-11-29 · New zircon and...
Transcript of New zircon and monazite geochronology from recent GOMA Drilling · 2015-11-29 · New zircon and...
New zircon and monazite geochronology from recent GOMA Drilling
Elizabeth JagodzinskiAnthony Reid
In 2008 Geoscience Australiaas part of its OnshoreEnergy SecurityProgram (OESP)collected deepseismic reflection dataacross the northernGawler Craton into theMusgrave Province. This was the GOMA seismic line
(Gawler-Officer-Musgrave-Amadeus)
The traverse followed the Adelaide to Darwin railway line for ~ 630 km, from Tarcoola in the south to the southern margin of the Amadeus Basin in the Northern Territory.
Due release date December, 2010
89m
4m12m
80m
169m
54m
6m
266m
132m
50m
4m
80m
172m
126m
257m
305m310m
462m
517m
DH1
SouthNorth
DH2 DH3 DH4
basementorthogneiss
basementparagneiss
+ amphibolite dykes
Eromanga Basin(Cretaceous)
Arckaringa Basin(Permian)
1
2
3
4
Tertiary/Quaternary cover
GOMA 1
GOMA 3
GOMA 2
GOMA 4
~1750 Ma~1750 Ma
~1750 Ma
pre-Kimban maximum depositional agesFanning et al., 2007; Payne et al., 2006
~1750 Ma
~1750 Ma
1740±31 Ma 1743±10 Ma
GOMA DH3 155.08-155.91m
R1707903
R1707903 unmetamorphosed well-bedded fine to coarse-grained sandstone GOMA DH3 155.08-155.91m
Provenance:• Gawler Craton• Musgrave Province
R1707903
R1707899
GOMA DH4
R1707899 sillimanite–biotite–quartz–feldspar paragneissGOMA DH2 75.4-75.8 m
R1707899
20 µm
GOMA DH1
285m 310.2 m
256.9 m305.15m
R1707896
R1707895
R1707895 Quartz-feldspar-biotite-magnetite orthogneissGOMA DH1 307.65-307.85 m
• Zoned, resorbed igneous cores• Darker, homogenous
metamorphic rims
R1707896
R1707895
R1707895 OrthogneissGOMA DH1 307.65-307.85 m
R1707895R1707896
GOMA 3
GOMA 2
GOMA 4
1728±10 Ma
1701±9 Ma
Kimban metamorphic agesPayne et al., 2008
1719±8 Ma
GOMA 1
1734±8 Ma
1686±5 Ma
R1707896Fine-grained biotite tonalite GOMA DH1 308.7-308.9 m
• Oscillatory zoned igneous cores • Dark homogenous metamorphic rims
R1707895R1707896
R1707896Fine-grined biotite tonalite GOMA DH1 308.7-308.9 m
R1707895R1707896
1568 ± 6 MaMSWD = 1.3
probability = 0.2n = 18
GOMA DH1
minor resettingat ca 1650 -1570 Ma
metamorphosedat 1690 Ma
emplaced at1920 Ma
emplaced andmetamorphosed
at ca 1570 Ma
R1707895R1707896
GOMA 3
GOMA 2
GOMA 4
1586±8 Ma
‘Kararan’ metamorphic agesFanning et al., 2007; Payne et al., 2006; 2008; Cutts et al., in press
1569±8 Ma
1578±7 Ma
~1560 Ma
~1590 Ma
GOMA 1
1568±6 Ma
GOMA DH4
465.4 m
516.8
494m
502m
R1707908
R1707907
R1707904
R1707908: quartz-feldspar-biotite-hornblende orthogneissGOMA DH4 510 m
• Abundant inheritance as small cores 2680 - 3170 Ma• Homogenous black to zoned cores ca 2520 Ma• Light CL rims ca 1523 Ma
R1707908
• Age pattern of cores consistent with Mulgathing Complex orthogneisses
GOMA 3
GOMA 2
GOMA 4
GOMA 1
• Age pattern of cores consistent with Mulgathing Complex orthogneisses
• No evidence of late Sleaford (2410 - 2450 Ma) or Kimban (1720-1690 Ma)
• Post Kararan (1570-1545) zircon growth at 1521 ± 9 Ma
• Low yield about 15 grains from 30 cm ¼ core
R1707904 quartz monzoniteKspar-quartz-plagioclase GOMA DH4 484 m
R1707904
R1707904quartz monzoniteGOMA DH4 484 m
No sign of zirconovergrowth at
1521 Ma
R1707904
1759 Ma
≤ 1520 Mahigh-level intrusion
1521 Mametamorphism?
magmatism?metasomatism?
DH4
emplaced atca 2520 Ma
ca 2560 Ma metamorphism?
granophyricleucocratic
monzo- to syenogranite
No sign of zirconovergrowth at
1521 Ma
} 1518 Ma
4
• Nearby high level, undeformed intrusions
• Monazites ca 1470 Ma(Swain unpublished)
• No zircon
Acknowledgements
• PIRSA Geological Survey of South Australia responsible for the GOMA Drilling team, in particular Rian Dutch, Marc Davies and Mark Flintoft.
• SHRIMP geochronology is undertaken as part of a National Geoscience Agreement between Geoscience Australa (GA) and PIRSA. The Geochronology group at GA is acknowledged for providing excellent preparation and analytical facilities and for valuable discussions on the methods and specifics of the northern Gawler Craton geochronology.
• Ben Wade at Adelaide Microscopy, the University of Adelaide is acknowledged for his patient and cheerful assistance with the LA-ICPMS work undertaken by AR.
• high resolution drill tray pictures were obtained using HyLoggerTM,a trade mark of CSIRO