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| | | | Geological Survey of Western Australia |
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| | | | HM Howard, R Quentin de Gromard, and RH Smithies | | | | | Type | Basin | Lithology | sedimentary and volcanic rocks | Parent unit | | Child units | No child units | Constituent lithostratigraphic units | | Affected by events | | Tectonic setting | |
| | | Summary | The Ramarama Basin is the basin into which the protoliths to the 1340–1270 Ma Wirku Metamorphics were deposited. Evidence for the basin is preserved in the rafts of banded gneiss from the Wirku Metamorphics found in younger granitic rock of the Musgrave Province. The Wirku Metamorphics consist of pelitic, arkosic, and near-orthoquartzitic interlayers, and is interpreted to have protoliths of sedimentary and rarer volcaniclastic and volcanic origin. Volcanic units of the Wankanki Supersuite are a component of the Wirku Metamorphics and are interlayered with the sedimentary rocks. The age of the Ramarama Basin is defined by the 1340–1270 Ma age of the Wirku Metamorphics. | | | Distribution | The Ramarama Basin is preserved by the outcrop of the Wirku Metamorphics (P_-_wm) as rafts within younger granitic rocks of the Musgrave Province. Since only relict fragments of the basin remain, the original extent of the Ramarama Basin is unknown. | | | Description | The basin into which the protoliths to the Wirku Metamorphics were deposited is referred to as the Ramarama Basin (Evins et al., 2012). The Wirku Metamorphics consist of banded gneiss, mainly preserved as rafts in granitic rocks of the west Musgrave Province. Based on locally continuous layering, the presence of pelitic, arkosic, and near-orthoquartzitic interlayers, and on complex zircon age spectra, this gneiss is interpreted to have had protoliths of sedimentary and rarer volcaniclastic and volcanic origin (e.g. Evins et al., 2012) deposited between c. 1340 and 1270 Ma. Volcanic units of the Wankanki Supersuite are a component of the Wirku Metamorphics and are interlayered with the sedimentary rocks. | | | | | | Geochronology | | | Ramarama Basin | Maximum age | Minimum age | Age (Ma) | 1340 | 1270 | Age | Mesoproterozoic | Mesoproterozoic |
| The age of the Ramarama Basin is defined by sixteen samples of the Wirku Metamorphics that have been dated by ion microprobe (SHRIMP). The approximate maximum depositional age is interpreted from an average of the youngest detrital zircon components (c. 1340 Ma; Evins et al., 2012). The minimum depositional age is constrained by crosscutting c. 1300 Ma granitic rocks of the Wankanki Supersuite in the Tjuni Purlka Tectonic Zone, and a 1319 ± 7 Ma felsic volcanic layer that is interleaved with metasedimentary units of the Wirku Metamorphics south of Mount Holt (GSWA 180867, Kirkland et al., 2009a). Together, these ages suggest that protoliths to the Wirku Metamorphics were, in most cases, deposited between c. 1340 and 1300 Ma. However, some exposures of paragneisses contain detrital zircon grains with cores apparently as young as c. 1270 Ma (GSWA 187115; Kirkland et al., 2009b). Thus, detailed analysis of detrital zircon age patterns from a large number of samples of the Wirku Metamorphics, collected throughout the west Musgrave Province (Evins et al., 2012), indicates that deposition of these supracrustal rocks into the Ramarama Basin took place between c. 1340 and 1270 Ma. | | | | Rocks of the Ramarama Basin form inclusions in the igneous rocks of the Pitjantjatjara and Wankanki Supersuites. | | | Tectonic setting | Sedimentary deposition of the protoliths to the c. 1340 and 1270 Ma Wirku Metamorphics into the Ramarama Basin, and magmatism of the c. 1345 to 1293 Ma Wankanki Supersuite, can be regarded as components of the Mount West Orogeny (Evins et al., 2012). Volcanic units of the Wankanki Supersuite are interlayered with, contributed detritus to, and are thus a component of, the Wirku Metamorphics in both the Mamutjarra Zone and the Tjuni Purlka Zone. However, no volcanic or intrusive rocks of this age are known from the Walpa Pulka Zone (BATES).
Deposition of sedimentary and volcanic rocks, coeval with the widespread magmatism of the calc-alkaline Wankanki Supersuite and the compressional deformation and crustal thickening that followed, are factors consistent with north and north-westward subduction and later arc-accretion on to the distal margin of the North Australian Craton. In this scenario, the Tjuni Purlka Zone may have also been initiated during the Mount West Orogeny as an incipient back-arc rift.
The coincidence of ages between the Mount West Orogeny and Stage I of the Albany–Fraser Orogeny was noted by White (1997) and it was suggested that the Musgrave Province and the Albany–Fraser Orogen formed a continuous orogenic belt at this stage. However, a syn- to post-accretionary tectonic setting is inferred for the Recherche Supersuite during Stage I of the Albany–Fraser Orogeny, immediately following the termination of eastward dipping subduction in the Madura Province to the east of the Albany–Fraser Orogen (Spaggiari et al., 2014). This is in contrast with the syn-subduction setting for the Wankanki Supersuite during the Mount West Orogeny (Howard et al., 2015). However, in a broad sense both the Wankanki and Recherche Supersuites may reflect the final stage in the Proterozoic amalgamation of central, western and southern Australia (e.g. Giles et al., 2004; Betts and Giles, 2006; Smithies et al., 2010).
| BookMark | | | | | Constituent lithostratigraphic units | | | Unit name | Unit code | Rank | GSWA status | | | Member | Informal | | | Formation | Formal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal | | | Member | Informal |
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| | | | | | References | Betts, PG and Giles, D 2006, The 1800-1100 Ma tectonic evolution of Australia: Precambrian Research, v. 144, p. 92–125. | Evins, PM, Kirkland, CL, Wingate, MTD, Smithies, RH, Howard, HM and Bodorkos, S 2012, Provenance of the 1340-1270 Ma Ramarama Basin in the west Musgrave Province, central Australia: Geological Survey of Western Australia, Report 116, 39p. | Giles, D, Betts, PG and Lister, GS 2004, 1.8 - 1.5-Ga links between the North and South Australian Cratons and the Early-Middle Proterozoic configuration of Australia: Tectonophysics, v. 380, p. 27–41. | 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, Bodorkos, S, Wingate, MTD and Smithies, RH 2009b, 187115.1: diatexitic migmatite, Mount Aloysius; Geochronology Record 792: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Kirkland, CL, Wingate, MTD, Evins, PM and Smithies, RH 2010a, 180867.1: quartz monzonite, Pirntirri Mulari; Geochronology Record 910: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Smithies, RH, Howard, HM, Evins, PM, Kirkland, CL, Kelsey, DE, Hand, M, Wingate, MTD, Collins, AS, Belousova, E and Allchurch, S 2010, Geochemistry, geochronology, and petrogenesis of Mesoproterozoic felsic rocks in the west Musgrave Province, Central Australia, and implications for the Mesoproterozoic tectonic evolution of the region: Geological Survey of Western Australia, Report 106, 73p. View Reference | Spaggiari, CV, Kirkland, CL, Smithies, RH, Occhipinti, SA and Wingate, MTD 2014, Geological framework of the Albany–Fraser Orogen, in Albany–Fraser Orogen seismic and magnetotelluric (MT) workshop 2014: extended abstracts: Geological Survey of Western Australia, Perth, Record 2014/6, p. 12–27. | White, RW 1997, The pressure-temperature evolution of a granulite facies terrain, western Musgrave Block, central Australia: Macquarie University, Sydney, New South Wales, PhD thesis (unpublished), 256p. |
| | | | Recommended reference for this publication | Howard, HM, Quentin de Gromard, R and Smithies, RH 2019, Ramarama Basin (RM): 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 20 June 2019. | | | | | 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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