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| | | | Geological Survey of Western Australia |
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| | | Mosquito Creek Orogeny (PCMQ) | AH Hickman | | | | | Event type | tectonic: orogeny | Parent event | | Child events | | Tectonic units affected | | Tectonic setting | orogen: collisional orogen | Metamorphic facies | | Metamorphic/tectonic features | faulted; folded; schistose; sheared |
| | | Summary | The Mosquito Creek Orogeny resulted from a north-northwesterly to south-southeasterly compression of the Mosquito Creek Basin between converging plates of the East Pilbara and Kurrana Terranes. The orogeny commenced following c. 2930 Ma closure of the Mallina Basin in the northwestern Pilbara Craton. Between c. 3165 and 2900 Ma the northwestern Pilbara Craton was subject to northwesterly to southeasterly compression due to convergence of a large plate northwest of the Karratha Terrane. This resulted in a succession of basin closures: firstly, the 3165–3070 Ma closure of the Regal Basin, culminating in the Prinsep Orogeny; secondly, the 2955–2919 Ma closure of the Mallina Basin during the North Pilbara Orogeny; and finally, the compression and closure of the Mosquito Creek Basin, the only remaining belt of thin crust at c. 2930 Ma.
At 2930 Ma the Mosquito Creek Basin is likely to have been at least 100 km wide, but compression during the orogeny converted it into a 30–35 km-wide synclinorium. Unlike the earlier Prinsep and North Pilbara Orogenies, the Mosquito Creek Orogeny was not accompanied by granitic intrusion, a feature consistent with the collision of continental plates. The orogeny evolved in three stages: the first stage producing regional-scale, tight to isoclinal folds plunging shallowly in east-northeast direction, accompanied by an east-northeasterly striking schistosity, extending throughout the basin and into the northern margin of the Kurrana Terrane. The second stage was confined to the local development of northerly trending and northerly plunging folds, producing a crenulation cleavage superimposed on the regional schistosity. The third stage produced regional-scale, tight upright folds, trending east-northeast in the west and east in the east. These folds have an axial plane foliation, and the limbs of the folds are locally disrupted by major shear zones, containing gold mineralization. | | | Distribution | Deformation and metamorphism of the orogeny are concentrated in the Mosquito Creek Basin and in the northern part of the Kurrana Terrane. However, there are only very limited geochronological data from the southeastern part of the East Pilbara Terrane to indicate the regional extent of metamorphism related to the orogeny. For example, a ⁴⁰Ar/³⁹Ar date of 2909 ± 12 Ma (hornblende) was obtained from amphibolite within the Mulgandinnah Shear Zone of the Shaw Dome (T94/215, Zegers, 1996), although it was interpreted to be a cooling age associated with nearby granitic intrusion. | | | Description | The Mosquito Creek Orogeny was the final orogeny in the northern Pilbara Craton and took place when the East Pilbara and Kurrana Terranes were forced together by north-northwesterly to south-southeasterly compression. The timing of the orogeny is indicated by a Pb–Pb model age of 2905 ± 9 Ma from gold mineralization within a shear zone (Thorpe et al., 1992). The orogeny commenced after c. 2930 Ma, following deposition of the Mosquito Creek Formation (Bagas et al., 2004). At 2930 Ma the Mosquito Creek Basin was probably at least 100 km wide, but compression during the orogeny converted it into a 30–35 km-wide synclinorium. Unlike the earlier orogenic events in the Pilbara Craton, the Mosquito Creek Orogeny was not accompanied by granitic intrusion of the basin under compression. Granitic intrusions of the 2954–2919 Ma Sisters Supersuite were emplaced northwest of the Mosquito Creek Basin, but these were related to subduction of a plate northwest of the Pilbara Craton.
The first stage of the orogeny (D18 in the deformation history of the northern Pilbara Craton, Hickman, 2021) produced regional-scale, tight to isoclinal folds shallowly plunging east-northeast, accompanied by an east-northeasterly striking schistosity extending throughout the basin and into the northern margin of the Kurrana Terrane. The second stage (D19) resulted in the local development of northerly trending and northerly plunging folds, producing a crenulation cleavage superimposed on the regional schistosity. The third stage (D20) produced regional-scale, tight upright folds, trending east-northeast in the west and east in the east. These folds have an axial plane foliation, and the limbs of the folds are locally disrupted by major shear zones, containing gold mineralization.
Compression of the Mosquito Creek Basin resulted in basin inversion, with the entire basin fill being tectonically thickened and uplifted. The marginal normal faults that originated during the c. 3200 Ma rift phase of basin development were re-activated as thrusts, and northern sections of the basin being thrust onto the East Pilbara Terrane. On the southern margin of the basin, the Coondamar Formation was thrust onto the Kurrana Terrane. Much of the southern thrusting apparently took place along the Kurrana Shear Zone.
Although the bulk of the Mosquito Creek Formation was deposited before the orogeny, parts of the succession were deposited during the deformation. Nijman et al. (2010) noted that conglomerate units in the North Dromedary and South Dromedary hills, 8 km south-southeast of Nullagine, unconformably overlie folded units of the Mosquito Creek Formation, but are folded and sheared by late deformation of the orogeny. | | | | | | Geochronology | | | Mosquito Creek Orogeny | Maximum age | Minimum age | Age (Ma) | 2930 | 2890 | Age | Mesoarchean | Mesoarchean | Age data type | Inferred | | References | | |
| Geochronological evidence of the timing of the Mosquito Creek Orogeny is provided by a 2905 ± 9 Ma Pb–Pb model age from galena associated with gold mineralization in a shear zone at the Mosquito Creek gold mine (Thorpe et al., 1992; Huston et al., 2002; Bagas, 2005).
The maximum age of the orogeny is constrained by two lines of evidence:
1. The Mosquito Creek Formation was deformed by the orogeny so its depositional age provides a constraint. Bagas et al. (2008) used U–Pb dating of detrital zircons in two samples of the formation to interpret maximum depositional ages between c. 2941 Ma (re-interpretation of data from GSWA 169200, Nelson, 2004a) and c. 2930 Ma (re-interpretation of data from GSWA 177131, Nelson, 2004b). Data from other samples of the formation indicated substantially older maximum depositional ages.
2. Compression of the Mosquito Creek Basin is interpreted to have followed closure of the Mallina Basin during the 2955–2919 Ma North Pilbara Orogeny (Hickman, 2021). Convergence of the Pilbara Craton with a large plate to the northwest resulted in a succession of basin closures between c. 3165 and c. 2900 Ma, the Mosquito Creek Basin in the eastern Pilbara being the last to be affected.
The minimum age of the orogeny is indicated by the ages of younger granitic units that contain no evidence of deformation. Two samples of the post-orogenic Cutinduna Supersuite in the Kurrana Terrane were dated at c. 2897 Ma (GSWA 178230, Nelson, 2005a; GSWA 178231, Nelson, 2005b).
Accordingly, the available evidence indicates that the Mosquito Creek Orogeny took place between c. 2930 and 2900 Ma. | | | Tectonic Setting | During extension of the northern Pilbara Craton between c. 3220 and 3165 Ma, the fill of the Mosquito Creek Basin was mainly basaltic, forming a substantial part of the Coondamar Formation. However, from c. 3165 Ma onwards a collision between the Pilbara Craton and a plate converging from the northwest halted plate separation. The East Pilbara Terrane remained isolated from the effects of the plate convergence until closure of the Regal Basin at c. 3070 Ma. There is no evidence of post-3165 Ma igneous activity or sedimentary deposition in either the East Pilbara Terrane or the Mosquito Creek Basin until after 3070 Ma.
Bagas et al. (2008) used U–Pb dating of eight detrital zircons selected from eight samples of the Mosquito Creek Formation to interpret a maximum depositional age of c. 2972 Ma. Alternatively, zircon data from two samples in their study suggested maximum depositional ages between c. 2941 Ma (re-interpretation of data from GSWA 169200, Nelson, 2004a) and c. 2930 Ma (re-interpretation of data from GSWA 177131, Nelson, 2004b). Significant deposition of the Mosquito Creek Formation is likely to have commenced following doming and erosion of the East Pilbara Terrane between c. 3015 and 2940 Ma (D15, Hickman, 2021).
Until c. 2930 Ma, compression of the northern Pilbara Craton was absorbed by closure of the Mallina Basin during the 2955–2919 Ma North Pilbara Orogeny. Deformation then moved to the relatively thin crust of the Mosquito Creek Basin. From c. 2930 and 2900 Ma the East Pilbara and Kurrana Terranes were forced together until they became amalgamated beneath the basin. By c. 2900 Ma all zones of weakness in the northern Pilbara Craton had been eliminated by terrane amalgamation, and the craton remained stable until the commencement of continental breakup at c. 2775 Ma. | | | | References | Bagas, L 2005, Geology of the Nullagine 1:100 000 sheet: Geological Survey of Western Australia, 1:100 000 Geological Series Explanatory Notes, 33p. View Reference | Bagas, L, Bierlein, FP, Bodorkos, S and Nelson, DR 2008, Tectonic setting, evolution, and orogenic gold potential of the late Mesoarchaean Mosquito Creek Basin, North Pilbara Craton, Western Australia: Precambrian Research, v. 160, p. 237–44. | Bagas, L, Farrell, TR and Nelson, DR 2004, The age and provenance of the Mosquito Creek Formation, in Geological Survey of Western Australia Annual Review 2003–04 edited by Geological Survey of Western Australia, Perth, Western Australia, p. 62–70. 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 | Huston, DL, Sun, S-S, Blewett, R, Hickman, AH, Van Kranendonk, MJ, Phillips, D, Baker, D and Brauhart, C 2002, The timing of mineralization in the Archean North Pilbara Terrain, Western Australia: Economic Geology, v. 97, p. 733–755. | Nelson, DR 2004a, 169200.1: coarse lithic–quartz sandstone, Branchies Well; Geochronology Record 94: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Nelson, DR 2004b, 177131.1: coarse-grained metasandstone, Lionel Well; Geochronology Record 529: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Nelson, DR 2005a, 178230.1: biotite granodiorite, Limestone Bore; Geochronology Record 574: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Nelson, DR 2005b, 178231.1: biotite monzogranite, Limestone Bore; Geochronology Record 575: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Nijman, W, Clevis, Q and De Vries, ST 2010, The waning stage of a greenstone belt: the Mesoarchean Mosquito Creek Basin of the East Pilbara, Western Australia: Precambrian Research, v. 180, p. 251–271. | Thorpe, R, Hickman, AH, Davis, DW, Mortensen, JK and Trendall, AF 1992, Constraints to models for Archaean lead evolution from precise U-Pb geochronology from the Marble Bar region, Pilbara Craton, Western Australia, in The Archaean: Terrains, processes and metallogeny: Proceedings for the Third International Archaean Symposium, 17–21 September 1990 edited by Glover, JE and Ho, SE: Geology Department and University Extension, The University of Western Australia, Perth, Western Australia, Publication 22, p. 395–408. | 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. |
| | | | Recommended reference for this publication | Hickman, AH 2024, Mosquito Creek Orogeny (PCMQ): 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 05 March 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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