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| | | | R Quentin de Gromard, HM Howard, and RH Smithies | | | | | Event type | tectonic: intracratonic orogeny | Parent event | _Top of Event list | Child events | | Tectonic units affected | | Tectonic setting | orogen: intracratonic orogen | Metamorphic facies | | eclogite: undivided | granulite: undivided | amphibolite: kyanite | greenschist: muscovite |
| Metamorphic/tectonic features | gneissose; mylonitic; foliated; C-S fabric; porphyroblastic; sheared; stretched; phyllonitic; phyllitic; schistose; migmatitic |
| | | Summary | The 630–520 Ma Petermann Orogeny is a large-scale intracontinental transpressional event that reactivated the boundary between the North, South and West Australian Cratons. This event is largely amagmatic and deformation is mainly localized along the northern edge of the Musgrave Province and the southern Amadeus Basin. Deformation during the Petermann Orogeny produced or reactivated east-trending crustal-scale faults and shear zones, over 600 kilometres long, that dissect the entire Musgrave Province, the most prominent of which include the Woodroffe Thrust and the Mann Fault. Thrusting along the gently south-dipping Woodroffe Thrust juxtaposed high-pressure granulite facies rocks of the Fregon Domain (hanging wall) against amphibolite facies rocks of the Mulga Park Domain (footwall). Peak metamorphic conditions during the Petermann Orogeny were attained in the Bates and Mann Ranges regions, between the Woodroffe Thrust and the Mann Fault (orogenic core), and approached eclogite facies (P = 10–14 kbar and T = 700–800°C). The older age bracket for the Petermann Orogeny was defined in the western end of the west Musgrave Province, in the Mitika area, which records metamorphic zircon growth at c. 630 Ma. Deformation ages related to the Petermann Orogeny are younger towards the east: peak metamorphic conditions in the orogenic core were attained at c. 570 Ma, and the development and exhumation of the Petermann Nappe Complex and eastern Musgrave Province continued at least until c. 520 Ma. | | | Distribution | The main locus of deformation and metamorphism related to the 630–520 Ma Petermann Orogeny is along the northern part of the Musgrave Province, north of the east-trending Mann Fault and along the southern margin of the Amadeus Basin where basement rocks of the Musgrave Region are tectonically interleaved with sedimentary rocks of Supersequence 1 of the Centralian Superbasin. The high-grade core of the orogen, with pervasive deformation, is between the Mann Fault and the Woodroffe Thrust. South of the Mann Fault, in the hinterland, deformation related to the Petermann Orogeny is largely restricted to narrow mylonite zones along faults and shear zones. The area north of the Woodroffe Thrust and up to the southern margin of the Amadeus Basin, commonly referred to as the Petermann Nappe Complex, forms the foreland fold-and-thrust belt of the Petermann Orogen. | | | Description | The 630–520 Ma Petermann Orogeny is a large-scale intracontinental transpressional event that reactivated the boundary between the North, South and West Australian Cratons (Sandiford and Hand, 1998; Camacho and McDougall, 2000; Li and Evans, 2011). Shortening and exhumation related to the Petermann Orogeny at least partly resulted in the 800 km long and 300 km wide, east-trending, positive gravity anomaly of the Musgrave Province in central Australia (Lambeck and Burgess, 1992; Aitken et al., 2009a,b). Teleseismic data, gravity modeling and deep seismic reflection data suggest a crustal-scale flower structure for the eastern part of the Musgrave Province (Lambeck and Burgess, 1992; Aitken et al., 2009b; Korsch and Kositcin., 2010), while the deep crustal architecture in the western Musgrave Province is largely asymmetric and north-verging (Howard et al., 2013; Quentin de Gromard et al., 2017a,b). Apart from minor pegmatite vein intrusions, the Petermann Orogeny is largely amagmatic.
Deformation during the Petermann Orogeny produced or reactivated east-trending crustal-scale faults and shear zones, over 600 kilometres long, that dissect the entire Musgrave Province. The most prominent of these structures are the Woodroffe Thrust, the Davenport Shear Zone, the Mann–Mitika Fault, the Hinckley–Ferdinand Fault, the Wankari–Piltardi Detachment, and magnetic lineaments interpreted as faults or shear zones, including the Wintiginna and Lindsay Lineaments (Bell, 1978; Lambeck and Burgess, 1992; Major and Connor, 1993; Camacho and McDougall, 2000; Aitken et al., 2009a). The shortening component of the transpressive system of the Petermann Orogeny was largely accommodated by north- to northeast-directed tectonic transport along the gently south-dipping Woodroffe Thrust and by folding and thrusting within the Petermann Nappe Complex (Scrimgeour et al., 1999; Edgoose et al., 2004; Flöttmann et al., 2004). The Woodroffe Thrust is a two to three kilometre-thick zone of mylonite, ultramylonite and pseudotachylite (Bell, 1978; Wex et al., 2017), exhumation along which resulted in the juxtaposition of high-pressure granulite facies rocks of the Fregon Domain (hanging wall) against amphibolite facies rocks of the Mulga Park Domain (footwall) (Maboko et al., 1992; Camacho and Fanning, 1995; Scrimgeour et al., 1999; Edgoose et al., 2004). Within the Mulga Park Domain, the Petermann Nappe Complex is the structural system where basement rocks of the Musgrave Region are tectonically interleaved with the basal sedimentary sequence of the Amadeus Basin (Scrimgeour et al., 1999; Edgoose et al., 2004; Flöttmann et al., 2004). The strike-slip component of the Petermann Orogeny transpressive system is mainly accommodated by steeply-dipping structures along and to the south of the Mann Fault (Camacho and McDougall, 2000; Aitken et al., 2009a). Right-lateral component appears to dominate in the eastern Musgrave Province, and left-lateral in the west Musgrave Province, possibly reflecting a component of orogen-parallel lateral extrusion either side the of the Petermann orogenic core (Howard et al., 2015; Quentin de Gromard et al., 2017b).
Peak metamorphic conditions during the Petermann Orogeny were attained in the Bates and Mann Ranges regions, between the Woodroffe Thrust and the Mann Fault (orogenic core), and approached eclogite facies (P = 10–14 kbar and T = 700–800°C) at c. 570 Ma (Scrimgeour and Close, 1999; Raimondo et al., 2010). The existence of regional-scale, flat-lying mylonitic fabrics with opposing sense of shear, which developed over a prolonged deformation history and at slow cooling rates, is consistent with a crustal channel flow model for the exhumation of the orogenic core, similar to that proposed for the Himalayan–Tibetan system (Raimondo et al., 2009, 2010; Walsh et al., 2013). P–T estimates immediately north of the Woodroffe Thrust are 6–7 kbar and ~650°C and were attained at c. 550 Ma (Scrimgeour and Close, 1999; Edgoose et al., 2004). Towards the north and across the Petermann Nappe Complex, metamorphic conditions attributed to the Petermann Orogeny progressively decrease from amphibolite facies to lower greenschist facies (Scrimgeour et al., 1999). Along-strike, orogen-parallel strain and metamorphic gradients are evidenced by the pervasive ductile deformation of the Bates and Mann Ranges regions, while in the eastern Musgrave Province, deformation associated with the Petermann Orogeny is restricted to mylonite and pseudotachylite development adjacent to the Woodroffe Thrust, and to low- to moderate-grade mylonite zones along nearby structures.
The older age bracket for the Petermann Orogeny was defined in the western end of the west Musgrave Province, in the Mitika area, which records metamorphic zircon growth at c. 630 Ma, closely followed by continuous cooling during exhumation along the Woodroffe Thrust from c. 623 to 565 Ma (Quentin de Gromard et al., 2016, 2017a). Deformation ages related to the Petermann Orogeny are younger towards the east: peak metamorphic conditions in the orogenic core were attained at c. 570 Ma and the development and exhumation of the Petermann Nappe Complex and eastern Musgrave Province continued at least until c. 520 Ma (Camacho and Fanning, 1995; Camacho, 1997; Raimondo et al., 2009, 2010; Walsh et al., 2013; Walsh, 2017). | | | | | | Geochronology | | | Petermann Orogeny | Maximum age | Minimum age | Age (Ma) | 630 | 520 | Age | Ediacaran | Cambrian | Age data type | Inferred | | References | | |
| Timing of the 630–520 Ma Petermann Orogeny has been constrained by multiple geochronology techniques including U–Pb zircon, titanite and rutile, K–Ar and Rb–Sr muscovite and biotite, ⁴⁰Ar/³⁹Ar hornblende, muscovite and biotite, and (U–Th)/He zircon and apatite.
The maximum age constraint of c. 630 Ma was identified in the western end of the west Musgrave Province, in the Mitika area (Quentin de Gromard et al., 2016, 2017a). No such dates have been reported elsewhere in the Musgrave Province; the central and eastern Musgrave Province preserve a younger deformation and metamorphic history ranging between c. 570 and 520 Ma (Camacho and Fanning 1995; Scrimgeour et al., 1999; Edgoose et al., 2004; Raimondo et al., 2009, 2010; Walsh et al., 2013; Walsh, 2017).
In the Mitika area, high-temperature conditions are indicated by metamorphic zircon growth at c. 630 Ma (GSWA 205194, Kirkland et al., 2014a; GSWA 208414, Kirkland et al., 2014b; Quentin de Gromard et al., 2016, 2017a, 2019). This was followed closely by cooling below ~425°C of the lower-grade periphery of the Mitika area at c. 623 and 613 Ma, as indicated by ⁴⁰Ar/³⁹Ar analyses of muscovite (Quentin de Gromard et al., 2017a). The higher-grade core of the Mitika area in turn cooled below ~425°C at c. 590 Ma, broadly contemporaneous with cooling of the Wanarn area, exhumed along the Woodroffe Thrust. The Wanarn area is traversed by major thrusts that display differential cooling across them. The central part of the Wanarn area, cooled below ~365°C at c. 584 Ma (⁴⁰Ar/³⁹Ar biotite cooling age), while the northwest corner was still at ~585°C and further cooled to ~425°C at c. 565 Ma (⁴⁰Ar/³⁹Ar hornblende and muscovite ages, respectively; Quentin de Gromard et al., 2017a). This suggests differential cooling of the Wanarn area during development of a regional antiformal stack and generation of minor granitic melt as indicated by the age of pegmatite intrusions at 592 ± 6 and 545 ± 39 Ma during exhumation (Quentin de Gromard et al., 2017a).
Thermochronology data across the orogenic core and across the Petermann Nappe Complex indicate a younger tectonometamorphic history. Peak metamorphic conditions (10–14 kbar, 700–800°C) in the core of the orogen were attained at c. 570 Ma, as indicated by U–Pb dates from cores of large titanite grains and from zircon rims (Raimondo et al., 2009, 2010). Subsequent cooling below 600–660°C (closure temperature of Pb diffusion in titanite) occurred between c. 550 and 540 Ma, as indicated by dates obtained from smaller titanite grains (Raimondo et al., 2009). Similarly, in the Cockburn Shear Zone and Mann Ranges region, U–Pb zircon data suggest that peak metamorphic temperatures of 720–760°C were attained at 544 ± 7 Ma, followed by cooling below 600–660°C at c. 521 Ma, indicated by U–Pb titanite data (Walsh et al., 2013; Walsh, 2017). U–Pb analyses of rutile indicate further cooling to 550–560°C at 498–472 Ma (Walsh et al., 2013). ⁴⁰Ar/³⁹Ar muscovite and biotite data from the Petermann Nappe Complex in Western Australia yielded dates ranging between c. 600 and 545 Ma (Walsh, 2017; Quentin de Gromard et al., 2019). The older dates of c. 600 and 598 Ma were obtained from the structurally higher part of the Petermann Nappe Complex and are interpreted as the age of the early stage of development of the fold-and-thrust system (Walsh, 2017). Similarly, in the Northern Territory, muscovite-bearing samples from the structurally higher part of the Petermann Nappe Complex yielded K–Ar dates of 586 ± 5 and 568 ± 5 Ma (Scrimgeour et al., 1999). The younger dates of 562–545 Ma were obtained from a structurally lower part of the Petermann Nappe Complex, the Dog Leg Anticline that folded the previously developed Wankari–Piltardi Detachment system, and are interpreted as the time of subsequent folding and formation of the Dog Leg Anticline. This demonstrates that the early stages of development of the thrust system of the Petermann Nappe Complex were followed by younger, out-of-sequence, internal deformation (Walsh, 2017; Quentin de Gromard et al., 2019). Zircon (U–Th)/He thermochronology from the northern end of the Petermann Nappe Complex indicates that cooling related to development of the backthrust system was completed by c. 520 Ma (Quentin de Gromard et al., 2019).
In the eastern Musgrave Province, synkinematic muscovite and biotite yielded ⁴⁰Ar/³⁹Ar, K–Ar and Rb–Sr dates ranging between c. 560 and 520 Ma, interpreted as the timing of the development of the Woodroffe Thrust and the timing of thrusting of the Fregon Domain over the Mulga Park Domain (Maboko et al., 1992; Camacho and Fanning, 1995). | | | Tectonic Setting | The 630–520 Ma Petermann Orogeny is an intracontinental compressional event that occurred in central Australia, thousands of kilometres away from any plate boundary and interpreted to result from far field stress generated at a convergent plate boundary during amalgamation of the Gondwana Supercontinent (Li and Evans, 2011; Raimondo et al., 2014; Quentin de Gromard et al., 2019). Alternatively, instead of in-plane stress transmission from a distant convergent boundary, the stress source may have been generated intraplate by mantle downwelling (Gorczyk et al., 2013). | | | | References | Aitken, ARA, Betts, PG and Ailleres, L 2009a, The architecture, kinematics, and lithospheric processes of a compressional intraplate orogen occurring under Gondwana assembly: The Petermann Orogeny, central Australia: Lithosphere, v. 1, no. 6, p. 343–357. | Aitken, ARA, Betts, PG, Weinberg, RF and Gray, DJ 2009b, Constrained potential field modeling of the crustal architecture of the Musgrave Province in central Australia: Evidence for lithospheric strengthening due to crust-mantle boundary uplift: Journal of Geophysical Research, v. 114, no. B12405, doi:10.1029/2008JB006194. | Bell, TH 1978, Progressive deformation and reorientation of fold axes in a ductile mylonite zone: The woodroffe thrust: Tectonophysics, v. 44, no. 1–4, p. 285–320. | Camacho, A 1997, An isotopic study of deep-crustal orogenic processes, Musgrave Block, central Australia: Australian National University, Canberra, Australian Capital Territory, PhD thesis (unpublished). | Camacho, A and Fanning, CM 1995, Some isotopic constraints on the evolution of the granulite and upper amphibolite facies terranes in the eastern Musgrave Block, central Australia: Precambrian Research, v. 71, p. 155–172. | Camacho, A and McDougall, I 2000, Intracratonic, strike-slip partitioned transpression and the formation of eclogite facies rocks: An example from the Musgrave Block, central Australia: Tectonics, v. 19, p. 978–996. | Edgoose, CJ, Scrimgeour, IR and Close, DF 2004, Geology of the Musgrave Block, Northern Territory: Northern Territory Geological Survey, Report 15, 46p. | Flöttmann, T, Hand, M, Close, DF, Edgoose, C and Scrimgeour, IR 2004, Thrust tectonic styles of the intracratonic Alice Springs and Petermann Orogens, central Australia, in Thrust tectonics and hydrocarbon systems edited by McClay, KR: American Association of Petroleum Geologists, Memoir 82, p. 538–557. | Gorczyk, W, Hobbs, B, Gessner, K and Gerya, T 2013, Intracratonic geodynamics: Gondwana Research, v. 24, no. 3–4, p. 838–848. | Howard, HM, Quentin de Gromard, R, Smithies, RH, Kirkland, CL, Korsch, RJ, Aitken, ARA, Gessner, K, Wingate, MTD, Blewett, RS, Holzschuh, J, Kennett, BLN, Duan, J, Goodwin, JA, Jones, T, Neumann, NL and Gorczyk, W 2013, Geological setting and interpretation of the northeastern half of deep seismic reflection line 11GA-YO1: west Musgrave Province and the Bentley Supergroup, in Yilgarn Craton – Officer Basin – Musgrave Province seismic and MT workshop edited by Neumann, NL: Geoscience Australia, Record 2013/28, p. 51–95. | Howard, HM, Smithies, RH, Kirkland, CL, Kelsey, DE, Aitken, A, Wingate, MTD, Quentin de Gromard, R, Spaggiari, CV and Maier, WD 2015, The burning heart - the Proterozoic geology and geological evolution of the west Musgrave Region, central Australia: Gondwana Research, v. 27, no. 1, p. 64–94, doi:10.1016/j.gr.2014.09.001. | Kirkland, CL, Wingate, MTD, Quentin de Gromard, R, Howard, HM and Smithies, RH 2014a, 205194: psammitic gneiss, Mitika Homestead; Geochronology Record 1203: Geological Survey of Western Australia, 5p., <www.dmirs.wa.gov.au/geochron>. View Reference | Kirkland, CL, Wingate, MTD, Quentin de Gromard, R, Howard, HM and Smithies, RH 2014b, 208414: quartzite, Mitika Homestead; Geochronology Record 1205: Geological Survey of Western Australia, 6p., <www.dmirs.wa.gov.au/geochron>. View Reference | Korsch, RJ and Kositcin, N (eds.) 2010, GOMA (Gawler Craton – Officer Basin – Musgrave Province – Amadeus Basin) Seismic and MT workshop 2010: Geoscience Australia, Record 2010/39, 162p. | Lambeck, K and Burgess, G 1992, Deep crustal structure of the Musgrave Block, central Australia: Results from teleseismic travel-time anomalies: Australian Journal of Earth Sciences, v. 39, p. 1–20. | Li, ZX and Evans, DAD 2011, Late Neoproterozoic 40° intraplate rotation within Australia allows for a tighter-fitting and longer-lasting Rodinia: Geology, v. 39, no. 1, p. 39–42. | Maboko, MAH, McDougall, I, Zeitler, PK and Williams, IS 1992, Geochronological evidence for ~530–550 Ma juxtaposition of two Proterozoic metamorphic terranes in the Musgrave Ranges, central Australia: Australian Journal of Earth Sciences, v. 39, no. 4, p. 457–471. | Major, RB and Conor, CHH 1993, Musgrave Block, in The Geology of South Australia: volume 1, the Precambrian edited by Drexel, JF, Preiss, WV and Parker, AJ: Geological Survey of South Australia, Adelaide, SA, Bulletin 54, p. 156–167. | Quentin de Gromard, R, Howard, HM, Kirkland, CL, Smithies, RH, Wingate, MTD and Jourdan, F 2017a, Post-Giles Event evolution of the Musgrave Province constrained by (multi-method) thermochronology, in GSWA 2017 extended abstracts: promoting the prospectivity of Western Australia: Geological Survey of Western Australia, Record 2017/2, p. 42–47. View Reference | Quentin de Gromard, R, Howard, HM, Smithies, RH, Wingate, MTD and Lu, Y 2017b, The deep seismic reflection profile 11GA-YO1 in the west Musgrave Province: An updated view: Geological Survey of Western Australia, Record 2017/8, 20p. | Quentin de Gromard, R, Kirkland, CL, Howard, HM, Wingate, MTD, Jourdan, F, McInnes, BIA, Danišík, M, Evans, NJ, McDonald, BJ and Smithies, RH 2019, When will it end? Long-lived intracontinental reactivation in central Australia: Geoscience Frontiers, v. 10, no. 1, p. 149–164, doi:10.1016/j.gsf.2018.09.003. | Quentin de Gromard, R, Wingate, MTD, Kirkland, CL, Howard, HM and Smithies, RH 2016, Geology and U–Pb geochronology of the Warlawurru Supersuite and MacDougall Formation in the Mitika and Wanarn areas, west Musgrave Province: Geological Survey of Western Australia, Record 2016/4, 29p. View Reference | Raimondo, T, Collins, AS, Hand, M, Walker-Hallam, A, Smithies, RH, Evins, PM and Howard, HM 2009, Ediacaran intracontinental channel flow: Geology, v. 37, no. 4, p. 291–294. | Raimondo, T, Collins, AS, Hand, M, Walker-Hallam, A, Smithies, RH, Evins, PM and Howard, HM 2010, The anatomy of a deep intracontinental orogen: Tectonics, v. 29, doi:10.1029/2009TC002504. | Raimondo, T, Hand, M and Collins, WJ 2014, Compressional intracontinental orogens: Ancient and modern perspectives: Earth-Science Reviews, v. 130, p. 128–153. | Sandiford, M and Hand, M 1998, Controls on the locus of intraplate deformation in Central Australia: Earth and Planetary Science Letters, v. 162, p. 97–110. | Scrimgeour, IR and Close, DF 1999, Regional high pressure metamorphism during intracratonic deformation: The Petermann Orogeny, central Australia: Journal of Metamorphic Geology, v. 17, p. 557–572. | Scrimgeour, IR, Close, DF and Edgoose, CJ 1999, Petermann Ranges, Northern Territory: Northern Territory Geological Survey, 1:250 000 Geological Map Series Explanatory Notes SG52–07, 59p. | Walsh, A 2017, Thermo-mechanical evolution of orogeny in the Musgrave Province: Geological Survey of Western Australia, Report 166, 188p. View Reference | Walsh, AK, Raimondo, T, Kelsey, DE, Hand, M, Pfitzner, HL and Clark, C 2013, Duration of high-pressure metamorphism and cooling during the intraplate Petermann Orogeny: Gondwana Research, v. 24, no. 3–4, p. 969–983, doi:10.1016/j.gr.2012.09.006. | Wex, S, Mancktelow, NS, Hawemann, F, Camacho, A and Pennacchioni, G 2017, Geometry of a large-scale, low-angle, midcrustal thrust (Woodroffe Thrust, central Australia): Tectonics, v. 36, no. 11, p. 2447–2476, doi:10.1002/2017TC004681. |
| | | | Recommended reference for this publication | Quentin de Gromard, R, Howard, HM and Smithies, RH 2020, Petermann Orogeny (PE): Geological Survey of Western Australia, WA Geology Online, Explanatory Notes extract, viewed 16 April 2025. <www.dmp.wa.gov.au/ens> |
| | | This page was last modified on 29 January 2020. | | | | | Grid references in this publication refer to the Geocentric Datum of Australia 1994 (GDA94). Locations mentioned in the text are referenced using Map Grid Australia (MGA) coordinates, Zones 49 to 52. All locations are quoted to at least the nearest 100 m. Capitalized names in text refer to standard 1:100 000 map sheets, unless otherwise indicated. WAROX is GSWA’s field observation and sample database. WAROX site IDs have the format ‘ABCXXXnnnnnnSS’, where ABC = geologist username, XXX = project or map code, nnnnnn = 6 digit site number, and SS = optional alphabetic suffix (maximum 2 characters). All isotopic dates are based on U–Pb analysis of zircon and quoted with 95% uncertainties, unless stated otherwise. U–Pb measurements of GSWA samples were conducted using a sensitive high-resolution ion microprobe (SHRIMP) in the John de Laeter Centre at Curtin University, Perth, Western Australia. Digital data related to WA Geology Online, including geochronology and digital geology, are available online at the Department’s Data and Software Centre and may be viewed in map context at GeoVIEW.WA. | | | Further details of geological publications and maps produced by the Geological Survey of Western Australia are available from: Information Centre Department of Mines, Industry Regulation and Safety 100 Plain Street EAST PERTH, WA 6004 Telephone: +61 8 9222 3459 Facsimile: +61 8 9222 3444 |
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