The Chewings Event: Intracratonic Orogeny in Mesoproterozoic ...
The Chewings Event: Intracratonic Orogeny in Mesoproterozoic ...
The Chewings Event: Intracratonic Orogeny in Mesoproterozoic ...
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<strong>The</strong> <strong>Chew<strong>in</strong>gs</strong> <strong>Event</strong>:<strong>Intracratonic</strong> <strong>Orogeny</strong> <strong>in</strong><strong>Mesoproterozoic</strong> AustraliaMart<strong>in</strong> Hand, Ben Wade, Kar<strong>in</strong> Barovich
<strong>Chew<strong>in</strong>gs</strong> <strong>Orogeny</strong>: Rework<strong>in</strong>g <strong>in</strong> theArunta: 1600-1570 MaFraser (2003)
<strong>Chew<strong>in</strong>gs</strong> <strong>Orogeny</strong>: Rework<strong>in</strong>g <strong>in</strong> theArunta: 1600-1570 MaTeyssier and Hobbs (1988)<strong>Chew<strong>in</strong>gs</strong> Range region:• High-stra<strong>in</strong> large-scale top plate Ntransport• Barrovian (600°C, 5-6 kbar)metamorphism.SW Arunta:• Top platesouth• Upperamphibolitegrade(700°C,5-6 kbar)metamorphism.
<strong>Chew<strong>in</strong>gs</strong> <strong>Orogeny</strong>: Rework<strong>in</strong>g <strong>in</strong> theArunta: 1600-1570 Ma400°C2-3 kbarCentral AruntaRegion:Greenschist togranulitegrade HGGmetamorphism800°C5-6 kbarN-Sshorten<strong>in</strong>g(~50%), topSW transport
<strong>Chew<strong>in</strong>gs</strong> <strong>Orogeny</strong>: Rework<strong>in</strong>g <strong>in</strong> theArunta: 1600-1570 MaCentral Arunta Region:N-S shorten<strong>in</strong>g, top SW transportGreenschist to granulite grade HHGmetamorphismTim<strong>in</strong>g of peak metamorphism <strong>in</strong> the AnmatjiraRangeGarnet-cordierite-sp<strong>in</strong>el-sillimanite-biotite-metapeliteTeyssier and Hobbs (1988)Williams et al., (1996)Vry et al., (1996)Rubatto et al., (2001)
Early Isan <strong>Orogeny</strong>: 1600-1570 MaInverted multi-stage rift complex3 phases of bas<strong>in</strong> developmentbetween c. 1760-1595 MaIsan <strong>Orogeny</strong> (c. 1600-1500)Conner & Page, (1995)Page & Sun, (1998)Rubenach et al., (2001)Giles & Nutman, (2002)1532 ± 7 Ma1595 ± 6 Ma1584 ± 17 Ma1585 ± 5 Ma
Early Isan <strong>Orogeny</strong>: 1600-1570 MaTommy Creek Block: prograde zoned up-P garnetsMH1480.55141 gt core141gt rim0.54148 gt core148 gt rim0.53MH141:1581.7 ± 4.879 gtMH148:1581.3 ± 7.1O’Dea et al., (2006)0.52141 WR148 WRMH79:1576.2 ± 6.60.5179 WR147Sm/ 144 Nd0 1 2 3 4
Georgetown Inlier et alGeorgetown InlierEtheridge Group (~ 1700-1600): equivalents to Isan SS2 & 3?Early N-S shorten<strong>in</strong>g & Up-PBarrovian amphibolite-grademetamorphism at and prior to1562 ± 4 Ma (Boger & Hansen,2004; Black et al , 2005).Dargalong and Yambo InliersGranulite-grade metamorphism1585 ± 5 Ma - 1576 ± 5 Ma.(Blewett et al., 1998).
<strong>Intracratonic</strong> <strong>Orogeny</strong> <strong>in</strong><strong>Mesoproterozoic</strong> AustraliaSummary of NAC ICO’st = 1600-1570(ish) MaHigh geothermal gradient’sContractional deformationWhat else washappen<strong>in</strong>g <strong>in</strong> early<strong>Mesoproterozoic</strong>Australia?<strong>The</strong> Musgrave BlockA comparatively juvenile felsicdom<strong>in</strong>atedvolume separat<strong>in</strong>gthe Gawler (SAP) from the NAC.
<strong>The</strong> Musgrave marg<strong>in</strong>? A driverToward a tectonic synthesis of theMusgrave Blockfor c. 1600-1570 Ma NAC ICO’s?• ca. 1.59-1.55 Ga felsic rocks of theMusgrave Block appear to have formed <strong>in</strong> asubduction related environment…..
<strong>The</strong> Musgrave marg<strong>in</strong>? A driverToward a tectonic synthesis of theMusgrave Blockfor c. 1600-1570 Ma NAC ICO’s?• ca. 1.59-1.55 Ga felsic rocks <strong>in</strong> the Musgrave BlockGranitic toGranodioriticCalc-alkal<strong>in</strong>etrendsSteeper REE slopeY and YbDepleted• Felsic rocks are dom<strong>in</strong>antlyjuvenile with respect tosurround<strong>in</strong>g older crustaldoma<strong>in</strong>s, have calc alkal<strong>in</strong>e trendsand HEE depletion.Wade et al., (2006)
<strong>The</strong> Musgrave marg<strong>in</strong>? A driverToward a tectonic synthesis of theMusgrave Blockfor c. 1600-1570 Ma NAC ICO’s?If there was a marg<strong>in</strong> – where might it go?Is there an early<strong>Mesoproterozoic</strong> suturebeneath the Cann<strong>in</strong>gBas<strong>in</strong> that forms part ofthe Musgrave mag<strong>in</strong>?
What controlled the ICToward a tectonic synthesis of theMusgrave Blockresponsiveness of the NAC?<strong>Chew<strong>in</strong>gs</strong>, Early Isan and Georgetown-Yambo systems had GTG ~40-60C km -1 .Early Isan <strong>Orogeny</strong>overlapped withbas<strong>in</strong> development.Were these ICorogens localisedby hot preorogenicbas<strong>in</strong>s?
What controlled the ICToward a tectonic synthesis of theMusgrave Blockresponsiveness of the NAC?1583 ± 9 Ma1577 ± 6 Ma1599 ± 10 Ma1575 ± 5 Ma1570 ± 9 Ma1569 ± 6 Ma1584 ± 17 Mae.g. McLaren et al., (1999)1585 ± 5 Ma1595 ± 6 Ma
<strong>Intracratonic</strong> <strong>Orogeny</strong> <strong>in</strong><strong>Mesoproterozoic</strong> AustraliaToward a tectonic synthesis of theMusgrave Blockca. 1600-1570 Ma high-Trework<strong>in</strong>g of the NAC wassynchronous with thedevelopment of a juvenile arcsystem (Musgrave Prov<strong>in</strong>ce).N-S IC short<strong>in</strong>g <strong>in</strong> the NACreflects convergence on themarg<strong>in</strong>.IC responsiveness of NAC<strong>in</strong>herited from pre-orogenicbas<strong>in</strong>s and localized hhp crust.Is there an early<strong>Mesoproterozoic</strong> suturebeneath the Cann<strong>in</strong>g Bas<strong>in</strong>?
Southern Australian ProterozoicCurnamona Prov<strong>in</strong>ceInversion of 1715-1640……..Ma Willyama Superbas<strong>in</strong>HGG metamorphism @ 1610-1590 Ma
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