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| | | | Geological Survey of Western Australia |
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| | | | AH Hickman | | | | | Event type | tectonic: accretionary orogeny | Parent event | | Child events | | Tectonic units affected | | Tectonic setting | orogen: accretionary orogen | Metamorphic facies | | Metamorphic/tectonic features | diatexitic; banded; gneissose |
| | | Summary | The Prinsep Orogeny was an event of deformation, metamorphism and granitic intrusion resulting from plate convergence and collision between the Mesoarchean West Pilbara Superterrane and the Paleoarchean East Pilbara Terrane. There is evidence of two collisions during the orogeny. Firstly, the West Pilbara Superterrane was formed by collision of the 3130–3093 Ma Sholl Terrane with the Karratha and Regal Terranes along the Sholl Shear Zone. Secondly, closure of the Regal Basin brought the West Pilbara Superterrane into contact with the East Pilbara Terrane. The precise timing of the first collision is uncertain, although it is inferred to have taken place after the c. 3093 Ma formation of the Sholl Terrane. Zircon age components in post-3060 Ma igneous and sedimentary rocks of the northwestern Pilbara Craton suggest that the total duration of collisional events might have spanned about 20 Ma from c. 3080 Ma to 3060 Ma.
During the orogeny, c. 3067 Ma tonalite–trondhjemite–granodiorite (TTG) intrusions of the Elizabeth Hill Supersuite were emplaced close to the western margin of the East Pilbara Terrane and beneath the Maitland Shear Zone in the northwestern Pilbara Craton. Three U–Pb zircon dates on intrusions of the supersuite range between c. 3068 and 3066 Ma. Deformation attributed to the Prinsep Orogeny includes thrusting on the Maitland Shear Zone and sinistral strike-slip movement on the Sholl Shear Zone. Large-scale thrusts close to the western margin of the East Pilbara Terrane in the Pilbara Well and East Strelley greenstone belts are attributed to the second plate collision at c. 3070 Ma. The main part of the East Pilbara Terrane was not significantly affected by the orogeny, although there is local evidence of some pre-existing shear zones being reactivated. | | | Distribution | Deformation, metamorphism and granitic intrusion of the Prinsep Orogeny were mainly restricted to pre-3060 Ma tectonic units of the West Pilbara Superterrane and the western margin of the East Pilbara Terrane. In contrast, a number of studies including ⁴⁰Ar/³⁹Ar dating of hornblende and biotite in the central and eastern parts of the East Pilbara Terrane (Zegers, 1996; Davids et al., 1997; Zegers et al., 1999; Kloppenburg, 2003) revealed only very limited evidence of crustal disturbances during the timeframe of the orogeny. The conclusion that the main part of the East Pilbara Terrane was not significantly affected by the orogeny is consistent with the scarcity of 3080–3060 Ma detrital zircon ages in sedimentary formations of the east Pilbara (data in Hickman, 2021). | | | Description | Recognition of the Prinsep Orogeny (Van Kranendonk et al., 2006) as an important event in the evolution of the northwestern Pilbara Craton was based on evidence from geological mapping on DAMPIER (Hickman, 2001, 2004; Hickman et al., 2001) and ROEBOURNE (Hickman (2002). Conclusions from the mapping and accompanying geochronology include:
1. Following 3130–3093 Ma volcanism and granitic intrusion, the Sholl Terrane (south of the Sholl Shear Zone) was tectonically juxtaposed against the Karratha and Regal Terranes and the Nickol River Formation (north of the Sholl Shear Zone).
2. Based on a complete mismatch of the stratigraphy of these units north and south of the Sholl Shear Zone, it is inferred that strike-slip movement exceeded 100 km.
3. The tectonic juxtaposition of the terranes was accompanied by intrusion of c. 3068 Ma tonalite (later assigned to the Elizabeth Hill Supersuite).
4. Post-3068 Ma erosion of the tonalite and of the Sholl Terrane led to c. 3130 to 3060 Ma detrital zircons being included in 3060–3015 Ma sandstone units of the Gorge Creek Group, some of which were deposited on both sides of the Sholl Shear Zone.
The tonalite compositions of the Elizabeth Hill Supersuite and of the older 3130–3093 Ma Railway Supersuite (Sholl Terrane), combined with Sm–Nd isotope data (Smithies et al., 2007; Hickman, 2016), are consistent with magma derivation by subduction and partial melting of relatively juvenile basaltic crust during compression and closure of the Regal Basin. Complete closure of the basin amalgamated the West Pilbara Superterrane with the East Pilbara Terrane (Van Kranendonk et al., 2010) during the Prinsep Orogeny. Large-scale thrusts in the Pilbara Well greenstone belt (SATIRIST) and the East Strelley greenstone belt (WODGINA), and major recumbent isoclinal folds in the Wodgina greenstone belt (WODGINA) are evidence of horizontal deformation related to the basin closure (Van Kranendonk et al., 2007, 2010). | | | | | | Geochronology | | | Prinsep Orogeny | Maximum age | Minimum age | Age (Ma) | 3068 ± 4 | 3066 ± 4 | Age | Mesoarchean | Mesoarchean | Age data type | Isotopic | | References | | |
| One constraint on the maximum age of the Prinsep Orogeny is that it followed final magmatic activity in the Sholl Terrane at c. 3093 Ma. Gneiss of the Caines Well granitic complex was dated at 3093 ± 4 Ma (GSWA 118965, Nelson, 1997). The timing of peak metamorphism during the orogeny is indicated by c. 3067 Ma dates on intrusions of the Elizabeth Hill Supersite. A date of 3068 ± 4 Ma was obtained on the Cliff Pool Tonalite (GSWA 142661, Nelson, 1998) and dates of 3068 ± 22 Ma (GSWA 169014, Nelson, 2002a) and 3066 ± 4 Ma (GSWA 169016, Nelson, 2002b) were reported from the Cockeraga Leucogranite in the Yule Dome of the East Pilbara Terrane.
The minimum age of the orogeny is constrained by the maximum depositional age of the Gorge Creek Group that unconformably overlies the Sholl and Karratha Terranes. Geochronology indicating the maximum depositional age of the Gorge Creek Group includes: a maximum depositional age of 3058 ± 7 Ma on sandstone underlying the Cleaverville Formation at Cleaverville (GSWA 127330, Nelson, 1998); and a date of 3060 ± 5 Ma on the same sandstone unit (samples C914 and C915, Kiyokawa et al., 2019). The oldest known igneous unit post-dating the Prinsep Orogeny is the Orpheus Supersuite. A date of 3024 ± 4 Ma was obtained from a mylonitized granitic rock of this supersuite in the Sholl Shear Zone (JS25, Smith et al., 1998), and a date of 3031 ± 9 Ma was reported from quartz porphyry intruding amphibolite-facies metabasalt of the Regal Formation (Kiyokawa et al., 2002). The preferred interpretation is that the Prinsep Orogeny took place between c. 3090 and 3060 Ma, with peak metamorphism at c. 3067 Ma.
| | | Tectonic Setting | The Prinsep Orogeny resulted from a collision between the West Pilbara Superterrane and the East Pilbara Terrane (Van Kranendonk et al., 2006, 2007, 2010; Hickman et al., 2010; Hickman and Van Kranendonk, 2012; Hickman, 2016, 2021). This collision took place within the Central Pilbara Tectonic Zone, although the plate convergence was driven by interaction between the Karratha Terrane and a large plate northwest of the Pilbara Craton. In view of the concealed extent of the Pilbara Craton (Hickman, 2016), the contact is inferred to have been located at least 100 km northwest of the position of the present Pilbara coastline. Following the Prinsep Orogeny, ongoing convergence resulted in the northwestern plate being subducted beneath the northwestern section of the Pilbara Craton. This part of the craton is concealed by submerged Phanerozoic units of the Northern Carnarvon Basin (Hickman, 2004, 2016).
Although no remnants of the northwestern plate have been identified, its subduction indicates that it had a more mafic composition than the Pilbara Craton (Hickman, 2021). One possibility is that the northwestern plate was partly composed of c. 3200 Ma basaltic crust formed during the Paleoarchean breakup of the Pilbara Craton during the East Pilbara Terrane Rifting Event. | | | | References | Davids, C, Wijbrans, JR and White, SH 1997, ⁴⁰Ar³⁹Ar laserprobe ages of metamorphic hornblendes from the Coongan Belt, Pilbara Western Australia: Precambrian Research, v. 83, no. 4, p. 221–242. | Hickman, AH 2001, Geology of the Dampier 1:100 000 sheet: Geological Survey of Western Australia, 1:100 000 Geological Series Explanatory Notes, 39p. View Reference | Hickman, AH 2002, Geology of the Roebourne 1:100 000 sheet: Geological Survey of Western Australia, 1:100 000 Geological Series Explanatory Notes, 35p. View Reference | Hickman, AH 2004, Two contrasting granite–greenstones terranes in the Pilbara Craton, Australia: Evidence for vertical and horizontal tectonic regimes prior to 2900 Ma: Precambrian Research, v. 131, p. 153–172. | Hickman, AH 2016, Northwest Pilbara Craton: A record of 450 million years in the growth of Archean continental crust: Geological Survey of Western Australia, Report 160, 104p. View Reference | Hickman, AH 2021, East Pilbara Craton: a record of one billion years in the growth of Archean continental crust: Geological Survey of Western Australia, Report 143, 187p. View Reference | Hickman, AH, Smithies, RH, Pike, G, Farrell, TR and Beintema, KA 2001, Evolution of the West Pilbara granite–greenstone terrane and Mallina Basin, Western Australia — a field guide: Geological Survey of Western Australia, Record 2001/16, 65p. View Reference | Hickman, AH, Smithies, RH and Tyler, IM 2010, Evolution of active plate margins: West Pilbara Superterrane, De Grey Superbasin, and the Fortescue and Hamersley Basins — a field guide: Geological Survey of Western Australia, Record 2010/3, 74p. View Reference | Hickman, AH and Van Kranendonk, MJ 2012, Early earth evolution: evidence from the 3.5 – 1.8 Ga geological history of the Pilbara region of Western Australia: Episodes, v. 35, no. 1, p. 283–297, doi:10.18814/epiiugs/2012/v35i1/028. | Kiyokawa, S, Aihara, Y, Takehara, M and Horie, K 2019, Timining and development of sedimentation of the Cleaverville Formation and a post-accretion pull-apart system in the Cleaverville area, coastal Pilbara Terrane, Pilbara, Western Australia: Island Arc, v. 28, no. 6, article no. e12324, 23p., doi:10.1111/iar.12324. | Kiyokawa, S, Taira, A, Byrne, T, Bowring, S and Sano, Y 2002, Structural evolution of the middle Archean coastal Pilbara terrane, Western Australia: Tectonics, v. 21, no. 1044, p. 1–24, doi:10.1029/2001TC001296. | Kloppenburg, A 2003, Structural evolution of the Marble Bar Domain, Pilbara granite-greenstone terrain, Australia: the role of Archaean mid-crustal detachments: Utrecht University, Utrecht, the Netherlands, PhD thesis (unpublished), 256p. | Nelson, DR 1997, 118965.1: equigranular biotite monzogranite gneiss, old highway – Sherlock River crossing; Geochronology Record 457: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Nelson, DR 1998, 127330.1: volcaniclastic sedimentary rock, Cleaverville; Geochronology Record 442: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Nelson, DR 1998, 142661.1: foliated biotite tonalite, Zebra Hill; Geochronology Record 409: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Nelson, DR 2002a, 169014.1: foliated biotite–hornblende quartz diorite, Mount Gratwick; Geochronology Record 139: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Nelson, DR 2002b, 169016.1: foliated leucocratic biotite quartz diorite, Mount Gratwick; Geochronology Record 140: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Smithies, RH, Champion, DC, Van Kranendonk, MJ and Hickman, AH 2007, Geochemistry of volcanic rocks of the northern Pilbara Craton, Western Australia: Geological Survey of Western Australia, Report 104, 47p. View Reference | Smith, JB, Barley, ME, Groves, DI, Krapež, B, McNaughton, NJ, Bickle, MJ and Chapman, HJ 1998, The Sholl Shear Zone, West Pilbara; evidence for a domain boundary structure from integrated tectonostratigraphic analysis, SHRIMP U–Pb dating and isotopic and geochemical data of granitoids: Precambrian Research, v. 88, p. 143–172. | Van Kranendonk, MJ, Hickman, AH, Smithies, RH, Williams, IR, Bagas, L and Farrell, TR 2006, Revised lithostratigraphy of Archean supracrustal and intrusive rocks in the northern Pilbara Craton, Western Australia: Geological Survey of Western Australia, Record 2006/15, 57p. View Reference | Van Kranendonk, MJ, Smithies, RH, Hickman, AH and Champion, DC 2007, Review: Secular tectonic evolution of Archean continental crust: interplay between horizontal and vertical processes in the formation of the Pilbara Craton, Australia: Terra Nova, v. 19, no. 1, p. 1–38. | Van Kranendonk, MJ, Smithies, RH, Hickman, AH, Wingate, MTD and Bodorkos, S 2010, Evidence for Mesoarchean (~3.2 Ga) rifting of the Pilbara Craton: The missing link in an early Precambrian Wilson cycle: Precambrian Research, v. 177, no. 1–2, p. 145–161, doi:10.1016/j.precamres.2009.11.007. | Zegers, TE 1996, Structural, kinematic, and metallogenic evolution of selected domains of the Pilbara granite–greenstone terrain: Geologica Ultraiectina, Utrecht University, Utrecht, the Netherlands, PhD thesis (unpublished), 208p. | Zegers, TE, Wijbrans, JR and White, SH 1999, ⁴⁰Ar/³⁹Ar age constraints on tectonothermal events in the Shaw area of the eastern Pilbara granite–greenstone terrain (Western Australia): 700 Ma of Archaean tectonic evolution: Tectonophysics, v. 311, p. 45–81. |
| | | | Recommended reference for this publication | Hickman, AH 2024, Prinsep Orogeny (PCO): Geological Survey of Western Australia, WA Geology Online, Explanatory Notes extract, viewed 05 August 2025. <www.dmp.wa.gov.au/ens> |
| | | This page was last modified on 28 May 2024. | | | | | 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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