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| | | Edmundian Orogeny D1e/M1e (CED1) | S Sheppard, SP Johnson, FJ Korhonen, and MTD Wingate | | | | | Event type | deformation: undivided | Parent event | | Child events | | Tectonic units affected | | Tectonic setting | orogen: intracratonic orogen | Metamorphic facies | | Metamorphic/tectonic features | schistose |
| | | Summary | The first deformation event attributed to the Edmundian Orogeny in the Gascoyne Province, D1e/M1e, is represented by inclusion trails in porphyroblasts from pelites in the Nardoo Hills area in the northern part of the Mutherbukin Zone. SHRIMP U–Pb monazite geochronology from a pelite sample yielded a weighted mean ²⁰⁷Pb*/²⁰⁶Pb* date of 1026 ± 12 Ma, which may approximate the age of D1e/M1e. The metamorphic grade of this event is currently unknown. | | | Distribution | Evidence for D1e is confined to the Nardoo Hills area, in the northern part of the Mutherbukin Zone. | | | Description | Evidence for D1e is restricted to inclusion trails within porphyroblasts in the Nardoo Hills area in the northern
part of the Mutherbukin Zone. | | | | | | Geochronology | | | Edmundian Orogeny D1e/M1e | Maximum age | Minimum age | Age (Ma) | 1026 | 995 | Age | Mesoproterozoic | Neoproterozoic | Age data type | Inferred | | References | | |
| There are no direct age constraints for the timing of D1e. Five samples of schist were collected from the Pooranoo and Leake Spring Metamorphics in the Nardoo Well area of the central Gascoyne Province (GSWA 180911, 180918, 191970, 191975, 191977). All of the schists contained a composite S1e/S2e fabric. Dating of monazite and xenotime revealed a wide range of ages between c. 1026 and c. 995 Ma (Sheppard et al., 2007). However, the oldest date, at 1026 ± 12 Ma, is decidedly older than the rest and may relate directly to the D1e event.
In light of the poor constraints, the maximum and minimum ages for D1e are taken to be the oldest and youngest dates of c. 1026 and c. 995 Ma. | | | Tectonic Setting | Some previous studies attributed the Edmundian Orogeny to far-field reactivation of the Capricorn Orogen during the break up of Rodinia (Powell et al., 1994) and the assembly of Gondwana (Fitzsimons, 2003). In contrast, Myers et al. (1996) suggested that the Edmundian Orogeny resulted from the collision of the North and West Australian Cratons between c. 1300 and c. 1100 Ma. However, dolerite sills dated at c. 1070 Ma (Wingate, 2002) that intrude the Edmund and Collier Groups are also deformed into easterly trending folds. More recent advances in understanding the amalgamation history of the Rodinia supercontinent indicate that the collision of the eastern margin of Australia with Laurentia occurred at c. 1000 Ma (Li et al., 2008 and references therein), a time coincident with the Edmundian Orogeny recorded here in the West Australian Craton. In most Rodinia reconstructions (i.e. Pisarevsky et al., 2003; Li et al,., 2008) the western margin of the West Australian Craton faces an open ocean, so if these configurations are correct, the Edmundian Orogeny must be a response to far-field plate stresses related to Rodinia assembly along the eastern margin of Australia. However, it is possible that the Edmundian Orogeny formed in response to plate collision/accretion along the western margin of the West Australian Craton and that current models of Rodinia are incomplete (Johnson, 2013). Uplift of the southern Capricorn Orogen between c. 950 and c. 850 Ma (Occhipinti, 2004, 2007) has been linked to collision of the Kalahari Craton with the western margin of Australia along the Pinjarra Orogen (Occhipinti, 2004). The Northampton and Mullingarra Inliers in the Pinjarra Orogen are interpreted to be allochthonous terranes, derived from the Albany Fraser Belt (Ksienzyk et al., 2007, 2012) that were metamorphosed at granulite and amphibolite facies, respectively at c. 1080 Ma, and intruded by granites at c. 1070 Ma. The inliers were thought to have been emplaced in their present position relative to the Yilgarn Craton in the Neoproterozoic (Fitzsimons, 2003) although, because they contain undeformed dolerites of the Mundine Well Dolerite, emplacement must have occurred prior to dolerite intrusion at c. 755 Ma. The metamorphism in the central Gascoyne Province is a minimum of 40 Ma younger than that in the Northampton Inlier. However, a pegmatite from the Northampton Inlier has been dated at 989 ± 2 Ma (Bruguier et al., 1999), suggesting that there could be other tectonothermal events in the Pinjarra Orogen coeval with the metamorphism and magmatism dated here (see also Ksienzyk et al., 2007). A comparison of the age of detrital zircons from metasedimentary rocks of the Northampton Inlier with similar, possibly correlative packages from the Maud Belt of Antarctica, reveals different ages suggesting that the Kalahari Craton – West Australian Craton association may not be valid (Ksienzyk et al., 2007). | | | | References | Bruguier, O, Bosch, D, Pidgeon, RT, Byrne, DI and Harris, LB 1999, U-Pb chronology of the Northampton Complex, Western Australia - evidence for Grenvillian sedimentation, metamorphism and deformation and geodynamic implications: Contributions to Mineralogy and Petrology, v. 136, p. 258–272. | Fitzsimons, ICW 2003, Proterozoic basement provinces of southern and southwestern Australia, and their correlation with Antarctica: Geological Society, London, Special Publications, v. 206, p. 93–130. | Johnson, SP 2013, The birth of supercontinents and the Proterozoic assembly of Western Australia: Geological Survey of Western Australia, Perth, Western Australia, 78p. View Reference | Ksienzyk, AK, Jacobs, J, Boger, SD, Kosler, J, Sircombe, KN and Whitehouse, MJ 2012, U-Pb ages of metamorphic monazite and zircon from the Northampton Complex: Evidence of two orogenic cycles in Western Australia: Precambrian Research, v. 198–199, p. 37–50. | Ksienzyk, AK, Jacobs, J, Kosler, J and Sircombe, KN 2007, A comparative provenance study of the late Mesoproterozoic Maud Belt (East Antarctica) and the Pinjarra Orogen (Western Australia): Implications for a possible Mesoproterozoic Kalahari-Western Australia connection, in Antarctica: a keystone in a changing world - online proceedings of the 10th international symposium on Antarctic earth sciences edited by Cooper, Alan and Raymond, C, Santa Barbara, California, USA, 26 August - 1 September 2007; USGS Open-File Report 2007–1047. | Li, ZX, Bogdanova, SV, Collins, AS, Davidson, A, Waele, B, Ernst, RE, Fitzsimons, ICW, Fuck, RA, Gladkochub, DP, Jacobs, J, Karlstrom, KE, Lu, S, Natapov, LM, Pease, V, Pisarevsky, SA, Thrane, K and Vernikovsky, V 2008, Assembly, configuration, and break-up history of Rodinia: A synthesis: Precambrian Research, v. 160, no. 1–2, p. 179–210, doi:10.1016/j.precamres.2007.04.021. | Myers, JS, Shaw, RD and Tyler, IM 1996, Tectonic evolution of Proterozoic Australia: Tectonics, v. 15, p. 1431–1446. | Occhipinti, SA 2004, Tectonic evolution of the southern Capricorn Orogen, Western Australia: Curtin University of Technology, Perth, Western Australia, PhD thesis (unpublished), 220p. | Occhipinti, SA 2007, Neoproterozoic reworking in the Paleoproterozoic Capricorn Orogen: Evidence from ⁴⁰Ar/³⁹Ar ages: Geological Survey of Western Australia, Record 2007/10, 41p. View Reference | Pisarevsky, SA, Wingate, MTD, Powell, CMcA, Johnson, SP and Evans, DAD 2003, Models of Rodinia assembly and fragmentation: Geological Society, London, Special Publications, v. 206, no. 1, p. 35–55, doi:10.1144/GSL.SP.2003.206.01.04. | Powell, CMcA, Preiss, WV, Gatehouse, CG, Krapež, B and Li, ZX 1994, South Australian record of a Rodinian epicontinental basin and its mid-Neoproterozoic breakup (~700 Ma) to form the Palaeo-Pacific Ocean: Tectonophysics, v. 237, p. 113–140. | Sheppard, S, Rasmussen, B, Muhling, JR, Farrell, TR and Fletcher, IR 2007, Grenvillian-aged orogenesis in the Palaeoproterozoic Gascoyne Complex, Western Australia: 1030–950 Ma reworking of the Proterozoic Capricorn Orogen: Journal of Metamorphic Geology, v. 25, p. 477–494. | Williams, SJ, Williams, IR, Chin, RJ, Muhling, PC and Hocking, RM (compilers) 1983, Mount Phillips, Western Australia: Geological Survey of Western Australia, 1:250 000 Geological Series Explanatory Notes, 29p. View Reference | Wingate, MTD 2002, Age and palaeomagnetism of dolerite sills of the Bangemall Supergroup on the Edmund 1:250 000 sheet, Western Australia: Geological Survey of Western Australia, Record 2002/4, 48p. View Reference |
| | | | Recommended reference for this publication | Sheppard, S, Johnson, SP, Korhonen, FJ and Wingate, MTD 2022, Edmundian Orogeny D1e/M1e (CED1): 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 09 March 2022. | | | | | 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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