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| | | | Geological Survey of Western Australia |
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| | | Capricorn Orogeny D2n/M2n (CCD2) | SP Johnson, S Sheppard, AM Thorne, and FJ Korhonen | | | | | Event type | deformation: undivided | Parent event | | Child events | | Tectonic units affected | | Tectonic setting | orogen: intracratonic orogen | Metamorphic facies | | greenschist: chlorite | amphibolite: sillimanite |
| Metamorphic/tectonic features | crenulated; faulted; schistose; sheared; retrogressed |
| | | Summary | The second tectonic fabric that can be attributed to the Capricorn Orogeny is referred to as D2n and the corresponding mineral assemblage M2n. This fabric is recognized in several structural and metamorphic zones in the Gascoyne Province, in the Errabiddy Shear Zone, in the Yarlarweelor Gneiss Complex, and in the Ashburton and Blair Basins in the northern part of the orogen. D2n structures in the Yarlarweelor Gneiss Complex were originally considered to be D3n structures and were correlated with a flat fabric in the rocks of the Bryah Group. However, it is now considered to be likely that these early fabrics formed during the 2005–1955 Ma Glenburgh Orogeny.
In the Yarlarweelor Gneiss Complex, D2n structures mainly comprise conjugate, ductile shear zones and faults. The same may be true of the Errabiddy Shear Zone, although it is difficult to rule out younger orogenic events as the cause of these structures. In the Limejuice Zone, D2n produced a strong foliation or gneissic layering subparallel to compositional layering within schists of the Leake Spring Metamorphics and within syntectonic granite batholiths of the Minnie Creek batholith, such as the Middle Spring Granite. Deformation was associated with amphibolite facies metamorphism at low pressure, as indicated by assemblages containing andalusite, cordierite, and fibrolite within the pelitic schists. In the Boora Boora Zone at the northern end of the Gascoyne Province and in the Ashburton and Blair Basins to the north, D2n structures comprise close to isoclinal, upright, non-cylindrical folds at various scales and associated strike-slip faults. All traces of D2n/M2n structures and mineral assemblages in the Mutherbukin and Mangaroon Zones, if they were originally present, have been obliterated by younger orogenic events. | | | Distribution | Structures that formed during the Capricorn Orogeny are present across the width (up to 300–350 km) of the Capricorn Orogen in several tectonic units. The second deformation recognized in the Yarlarweelor Gneiss Complex (D2n) correlates with northerly trending folds, faults, and locally an upright foliation [‘D3’ and ‘S3’ of Occhipinti and Myers (1999) and Pirajno et al. (2000)] in the Bryah and Padbury Basins to the east and southeast of the complex. In the Yarlarweelor Gneiss Complex, D2n structures consist of conjugate east- to east-southeasterly and southeast- to south-southeasterly striking shear zones and faults [‘D3n’ of Sheppard and Swager (1999) and Occhipinti and Myers (1999)].
Farther north in the Glenburgh Terrane, i.e. in the northern part of the Mooloo Zone, and in the Mutherbukin and Limejuice Zones, only one period of deformation and metamorphism is recognizable. In the southern part of the Mooloo and the Paradise Zones where D1n is prevalent, D2n is most likely to be represented as a composite S1n–S2n low-grade schistosity to foliation. In the Limejuice Zone, metasedimentary schists of the Leake Spring Metamorphics, deformed during intrusion by granites of the Minnie Creek batholith, preserve an S2n gneissic fabric that is invariably folded around F3n folds.
D2n folds and fabrics are well developed at the northern end of the Gascoyne Province in the Boora Boora Zone and in the Ashburton and Blair Basins. Thorne and Seymour (1991) recognized three structural zones within the Ashburton Basin based on the geometry of the D2n structures and the preservation of D1n structures. Zone B represents a relatively high-strain zone formed during D2n, in which the recognition of D1n structures is typically difficult because strong overprinting by D2n has resulted in the early cleavage (S1n) being coaxial, and commonly coplanar with the later fabric (S2n). Zone C to the south occupies the remainder of the Ashburton Basin on ULLAWARRA and CAPRICORN, between the southwestern boundary of Zone B and the Edmund Group unconformity. It is distinguished from Zone B by its generally lower level of D2n strain, leading to the better preservation of D1n structures, and also by the presence of large-scale F2n folds and dextral wrench faults. | | | Description | In the Bryah and Padbury Basins adjacent to the Yarlarweelor Gneiss Complex, D2n structures consist of northerly trending folds, faults, and an upright foliation. The Kinders and Billara Faults are interpreted to be D2n structures. The effects of D2n decrease eastward away from the gneiss complex. The D2n event was also responsible for the doubly plunging nature of the Robinson Syncline and Peak Hill Anticline [D3 of Pirajno et al. (2000)]. Pirajno et al. (2000) interpreted D1n and D2n as a continuum, with a single recognizable metamorphic event [M1n; M2 of Pirajno et al. (2000)].
In the Yarlarweelor Gneiss Complex, D2n structures consist mainly of conjugate ductile shear zones and faults in two orientations: 080–110° and 140–170°. The largest of these structures is the Morris Fault, which is a splay off the Errabiddy Shear Zone. Dykes of medium-grained monzogranite (P_-MO-gmeb), one of which was dated at 1797 ± 4 Ma, are widely intruded into conjugate D2n faults. These faults are associated with small, upright, open to tight folds. The Kerba and Seabrook Faults may be at least in part in D2n structures (Occhipinti and Myers, 1999). In the granitic gneisses and Moorarie Supersuite granites of the Yarlarweelor Gneiss Complex, the M2n overprint consists of recrystallized quartz and biotite, partial replacement of plagioclase by albite, sericite, and clinozoisite, and retrogression of microcline to albite and sericite. Ilmenite crystals are commonly rimmed by titanite. In both the Archean and Paleoproterozoic amphibolites, mineral growth during M2n consists of titanite replacement of ilmenite and partial replacement of andesine by epidote, untwinned plagioclase, and calcite. In addition, hornblende is commonly partly replaced by finer grained actinolite. In the Archean and Paleoproterozoic calc-silicate gneisses, epidote, green hornblende, albite, and titanite partly or largely replace high-grade assemblages.
Farther west, rocks in the Errabiddy Shear Zone are cut by numerous subvertical, brittle–ductile shear zones and faults that trend east or east-southeast and have been assigned to D2n. These structures range from shear zones a few metres wide, up to zones about one hundred metres wide marked by upright, open to close folds, and a foliation of variable intensity. Fold plunges range from shallow to nearly vertical towards the southeast. In strongly sheared granitic gneisses and interlayered amphibolite and metamorphosed ultramafic rock, D2n structures may consist of a crenulation cleavage, the axis of which typically plunges steeply to the southeast. Most of the faults and shears are marked by a dextral offset ranging from 1 cm up to a few hundred metres. In places, probably during D2n, shallowly plunging, east-northeasterly trending F1n folds were rotated into steeply plunging, east-southeasterly trending folds.
In the Errabiddy Shear Zone, medium- and high-grade assemblages that formed during the Glenburgh Orogeny (M2g) in pelitic rocks of the Quartpot Pelite are variably overprinted by a lower grade metamorphic event. However, it is unclear as to how much, if any, of this retrogression belongs to M2n, rather than younger tectono-thermal events (Mangaroon and Edmundian Orogenies). Plagioclase is moderately to extensively replaced by fine-grained sericite, epidote, and albite, and garnet is partly altered to fine-grained biotite and muscovite. Sillimanite is entirely replaced by fine-grained mats of sericite. K-feldspar is partly replaced by sericite, quartz, and albite. Accompanying these mineralogical changes is the recrystallization of quartz and biotite and the development of granophyric and myrmekitic textures.
In the Glenburgh Terrane, only one set of structures has been identified that could be attributed to the Capricorn Orogeny. In the southern part of the Mooloo Zone and in the Paradise Zone this fabric is likely to represent a composite S1n–S2n fabric. Farther north in the northern part of the Mooloo Zone, the fabric most likely represents S2n only. The main difference between the two areas appears to be the grade of metamorphism, which was slightly higher to the south, resulting in the retrogression of peak amphibolite M2g assemblages to upper greenschist facies with the pseudomorphing of garnet with chloritoid. In the northern part of the Mooloo Zone, garnet has been retrogressed to mats of white mica–sericite–chlorite, indicating the lower greenschist facies.
In the central part of the Gascoyne Province, in particular the Mutherbukin Zone, it is commonly difficult to identify any structures related to the Capricorn Orogeny because of the effects of late Paleoproterozoic to early Neoproterozoic reworking. Indications of medium- to high-grade metamorphism in the Mutherbukin Zone are provided by 1772 ± 6 Ma metamorphic rims on detrital grains from a quartzite (GSWA 187403; Wingate et al., 2010a) sampled from northwestern YINNETHARRA, although no structures can be confidently linked to this metamorphism. It is equally possible that these metamorphic zircon rims grew during the D3n event.
In the Limejuice Zone, pelitic and psammitic schists comprise inclusions and rafts within granites of the Minnie Creek batholith. An early gneissic layering or schistosity (S2n) is crenulated by an upright schistosity (S3n) associated with growth of muscovite and chlorite (M3n) and patches of felted sericite 4–7mm in diameter (after ?andalusite). The M2n assemblages in pelitic rocks are wholly retrogressed, but probably consisted of muscovite–biotite–quartz–andalusite. In the Limejuice Zone on PINK HILLS and CANDOLLE a D2n/M2n gneissic layering in pelitic rocks is preserved in widely scattered localities marked by low-D3n strain. Even in most of these localities, the M2n assemblages are strongly retrogressed, although in places relict domains of M2n assemblages persist. In the Pink Hills, for example at site SXSPKH008182 (Zone 50, MGA 492473E 7276916N), pelitic gneiss or granofels comprises andalusite, cordierite, biotite, muscovite, and quartz. The mafic rocks in the Limejuice Zone commonly preserve M2n assemblages (along with a D2n/M2n gneissic fabric) much better than the pelites. The mafic rocks are now amphibolites with a fine-grained polygonal texture, and comprise hornblende (straw-yellow–green–dark green), plagioclase, quartz, titanomagnetite, and minor biotite. The Middle Spring Granite in the Limejuice Zone on PINK HILLS also contains a D2n fabric parallel to that in the pelites and amphibolites.
In the northern part of the orogen, the map patterns in the Boora Boora Zone are primarily a function of structures formed during D2n. Metre-scale upright, close to tight folds are developed throughout the zone and mostly plunge to the northwest. These fold the S1n foliation or gneissic layering and are associated with an axial planar foliation of variable intensity. An intersection lineation (S1n/S2n) that plunges parallel to the F2n fold axes is extensively developed. The vergence of metre-scale folds in the northwestern corner of MAROONAH can be used to define a megascopic, northwesterly plunging synform.
The S2n fabric on MAROONAH is primarily defined by the widespread development in the granitic rocks of chlorite (after biotite) and sericite. All rock compositions are marked by replacement of plagioclase formed during M1n by albite–oligoclase, sericite, and clinozoisite. In mafic rocks, magnetite and ilmenite have been pseudomorphed by epidote and titanite, respectively, in association with plagioclase recrystallization. Pelitic rocks show extensive replacement of garnet by chlorite and pseudomorphs of very fine-grained sericite after andalusite. Biotite and muscovite formed during M1n are largely recrystallized to chlorite and sericite. Collectively, these assemblages suggest greenschist facies conditions during M2n.
Most of the obvious folding and faulting in the Ashburton and Blair Basins results from the D2n event. Within Zone B of the Ashburton Basin, D2n deformation has resulted in tight to isoclinal, non-cylindrical F2n folds with wavelengths of 5–200 m. Folds trend west to northwest and are associated with a pronounced axial plane cleavage (S2n), which typically dips 60–90° to the southwest or northeast. Within the main body of Ashburton Formation rocks, faults are generally associated with subparallel quartz veins and are commonly observed to cut out all or part of the northern limb of the F2n folds. This fact, combined with a lack of marker horizons in the Ashburton Formation and the tight to isoclinal folding, creates a false impression of a simple stratigraphy and southwesterly dipping beds throughout much of Zone B. In such cases, evidence for F2n folding comes from local reversals in younging direction and the presence of isolated F2n fold closures within the otherwise uniformly dipping Ashburton Formation.
F2n folds in Zone C are large (100–6000 m wavelength), non-cylindrical, and trend west to northwest. Most plunge 10–40° (up to 80° locally) to the southeast or northwest. Axial planes dip steeply to the southwest or northeast. Close to the northern margin of Zone C, folds are open to tight (or locally isoclinal), although they are generally more open in central and southwestern parts of the fold belt. S2n is a penetrative slaty cleavage in the more easterly outcrops, although it is present as a crenulation cleavage farther west.
Numerous west-northwesterly to north-northwesterly trending wrench faults are parallel to the F2n fold axes or crosscut them at a shallow angle. Locally, a dextral displacement of up to 3 km can be measured. In general, however, a lack of marker horizons within the Ashburton Formation makes it difficult to assess accurately the amount of relative movement. The northern margin of the Capricorn Range is marked locally by a steep, southward-dipping fracture. Many faults are marked by a line of en echelon quartz veins, dipping 30–90° northeast or southwest. Locally, they are associated with a second suite of steeply dipping veins that trend between north-northwest and north-northeast. Most veins consist of equant to prismatic, subhedral to anhedral quartz with irregular goethite vugs (after sulfide). Locally, quartz crystals are kinked as a result of progressive fault movement. Low-grade metamorphism accompanied D2n in the Ashburton and Blair Basins and caused the retrogression of biotite to chlorite and andalusite to sericite, and the local growth of porphyroblastic muscovite. | | | | | | Geochronology | | | Capricorn Orogeny D2n/M2n | Maximum age | Minimum age | Age (Ma) | 1800 | 1784 | Age | Paleoproterozoic | Paleoproterozoic | Age data type | Inferred | | References | | |
| Geochronological constraints on the age of D2n mainly come from the Yarlarweelor Gneiss Complex and in the Limejuice Zone. Elsewhere, the absolute ages of D2n fabrics are poorly known. In the Yarlarweelor Gneiss Complex, the youngest granitic rock cut by D2n structures is the Kerba Granite dated at 1808 ± 6 Ma (Nelson, 1998a). Dykes of medium-grained monzogranite (P_-MO-gmeb) are widely emplaced into D2n faults and display a range of textures from massive to foliated, implying that they were intruded coevally with D2n. One of these dykes on MARQUIS (Nelson, 1998b) has been dated at 1797 ± 4 Ma (Sheppard and Swager, 1999).
In the Glenburgh Terrane, however, rocks of the Dumbie Granodiorite dated between c. 1811 and 1804 Ma were deformed during the D1n event and are crosscut by undeformed massive granite of the Scrubber Granite, the oldest intrusion of which is dated at 1800 ± 7 Ma (GSWA 168939, Nelson, 2001). This suggests that D2n in the southern part of the orogen did not commence until after c. 1800 Ma.
Farther north in the Limejuice Zone, folded and crenulated metasedimentary rocks of the Leake Spring Metamorphics on EUDAMULLAH are intruded by granitic rocks as old as c. 1810 Ma and as young as c. 1785 Ma. The older granitic rocks contain an upright foliation, although it is not clear whether this fabric is related to D2n or to a younger event. Nevertheless, the younger granitic rocks provide a younger age limit for D2n. The Middle Spring Granite contains a gneissic fabric parallel to that in the Leake Spring Metamorphics. The granite has an igneous crystallization age of 1788 ± 7 Ma (Wingate et al., 2011), which provides an older age limit for D2n/M2n in this zone. The Rubberoid Granite on PINK HILLS, which intrudes the gneissic fabric in the Middle Spring Granite, was sampled at two localities for SHRIMP U–Pb zircon dating. The samples yielded igneous crystallization ages of 1791 ± 4 Ma (GSWA 190660, Wingate et al., 2012) and 1786 ± 6 Ma (GSWA 188974, Wingate et al., 2017a), providing a younger age limit for D2n/M2n. Therefore, the S2n gneissic fabric and the associated high-T/low-P M2n metamorphism, was coeval with the construction of the Minnie Creek batholith. A preliminary U–Pb monazite age of c. 1785 Ma for schist along the northern margin of the Minnie Creek batholith (GSWA, unpublished data) confirms the presence of Capricorn Orogeny-aged deformation and metamorphism. A psammitic schist from the northern part of the Mooloo Zone yielded a single metamorphic zircon rim grown around older detrital cores. This rim was dated at 1788 ± 12 Ma (GSWA 184160; Wingate et al., 2010b) and is within uncertainty of the other ages for D2n/M2n obtained here.
In the northern part of the orogen, the timing of the S2n event is poorly constrained. In the Ashburton and Blair Basins, D2n took place sometime after c. 1800 Ma, which is the age of the oldest post-D1n granitic and felsic volcanic and volcaniclastic rocks that were affected by D2n folding and cleavage formation (Krapež and McNaughton, 1999; Wingate et al., 2014, 2017b,c). The minimum age of D2n is constrained in the Boora Boora Zone by a SHRIMP U–Pb zircon date on a monzogranite dyke (GSWA 169086, Nelson, 2004) that intruded parallel to the axial surface of an F2n fold and which truncates the S1n foliation. The dyke has an igneous foliation parallel to S2n and it was probably intruded during or after D2n. Hence, the date of 1784 ± 5 Ma for this dyke provides an estimate for the age of D2n.
| | | Tectonic Setting | The Capricorn Orogeny has been widely, although not universally, attributed to oblique collision of the Archean Yilgarn and Pilbara Cratons, following the model of Tyler and Thorne (1990) and Thorne and Seymour (1991). Since then, it has been recognized that some structures previously attributed to the Capricorn Orogeny belong to the older Ophthalmia and Glenburgh Orogenies (Powell and Horwitz, 1994; Occhipinti and Sheppard, 2001), although modifications of the earlier interpretation prevail (Evans et al., 2003). Krapež (1999) and Krapež and Martin (1999) considered that the Capricorn Orogeny reflected deformation along a sinistral transcurrent megashear, although little evidence was advanced to support this interpretation. Some objections to the interpretation of the Capricorn Orogeny as reflecting oblique collision of the Yilgarn and Pilbara Cratons were raised by Sheppard (2004, 2005) and Sheppard et al. (2010), who interpreted the orogeny as reactivation in an intracontinental setting.
A difficulty in advancing the understanding of the Capricorn Orogeny is the extensive nature of later Paleoproterozoic and Neoproterozoic reworking of the orogen. These reworking events have obliterated many of the fabrics, kinematic indicators, and mineral assemblages that formed during the Capricorn Orogeny. In the Errabiddy Shear Zone, Occhipinti et al. (2004) and Reddy and Occhipinti (2004) showed that deformation related to the Capricorn Orogeny probably reflects dextral transpression. Along the northern margin of the Capricorn Orogen, Thorne and Seymour (1991) interpreted the Ashburton Basin as a foreland basin to collision between the Yilgarn and Pilbara Cratons, with uplift of the Gascoyne Province and thrust stacking to the south of the basin. In large part, this model was based on the sedimentology of the Ashburton Formation and, even if the orogeny does not reflect continent–continent collision, it clearly involved substantial compression and uplift of the Gascoyne Province. | | | | References | Evans, DAD, Sircombe, KN, Wingate, MTD, Doyle, M, McCarthy, M, Pidgeon, RT and van Niekerk, HS 2003, Revised geochronology of magmatism in the western Capricorn Orogen at 1805-1785 Ma: Diachroneity of the Pilbara-Yilgarn collision: Australian Journal of Earth Sciences, v. 50, no. 6, p. 853–864. | Krapež, B 1999, Stratigraphic record of an Atlantic-type global tectonic cycle in the Palaeoproterozoic Ashburton Province of Western Australia: Australian Journal of Earth Sciences, v. 46, p. 71–87. | Krapež, B and Martin, DMcB 1999, Sequence stratigraphy of the Palaeoproterozoic Nabberu Province of Western Australia: Australian Journal of Earth Sciences, v. 46, no. 1, p. 89–103, doi:10.1046/j.1440-0952.1999.00692. | Krapež, B and McNaughton, NJ 1999, SHRIMP zircon U-Pb age and tectonic significance of the Palaeoproterozoic Boolaloo Granodiorite in the Ashburton Province, Western Australia: Australian Journal of Earth Sciences, v. 46, p. 283–287. | Nelson, DR 1998a, 142851.1: recrystallized monzogranite, Kerba Pool; Geochronology Record 367: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Nelson, DR 1998b, 142852.1: recrystallized monzogranite dyke, Dunes Well; Geochronology Record 368: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Nelson, DR 2001, 168939.1: biotite monzogranite, Trickery Bore; Geochronology Record 209: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Nelson, DR 2004, 169086.1: biotite monzogranite, Boora Boora Bore; Geochronology Record 117: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Occhipinti, SA and Myers, JS 1999, Geology of the Moorarie 1:100 000 sheet: Geological Survey of Western Australia, 1:100 000 Geological Series Explanatory Notes, 20p. View Reference | Occhipinti, SA and Sheppard, S 2001, Geology of the Glenburgh 1:100 000 sheet: Geological Survey of Western Australia, 1:100 000 Geological Series Explanatory Notes, 37p. View Reference | Occhipinti, SA, Sheppard, S, Passchier, C, Tyler, IM and Nelson, DR 2004, Palaeoproterozoic crustal accretion and collision in the southern Capricorn Orogen: The Glenburgh Orogeny: Precambrian Research, v. 128, p. 237–255. | Pirajno, F, Occhipinti, SA and Swager, CP 2000, Geology and mineralization of the Palaeoproterozoic Bryah and Padbury Basins, Western Australia: Geological Survey of Western Australia, Report 59, 52p. View Reference | Powell, CMcA and Horwitz, RC 1994, Late Archaean and Early Proterozoic tectonics and basin formation of the Hamersley Ranges, in Excursion Guidebook 4: 12th Australian Geological Convention: Geological Society of Australia. | Reddy, SM and Occhipinti, SA 2004, High-strain zone deformation in the southern Capricorn Orogen, Western Australia: Kinematics and age constraints: Precambrian Research, v. 128, p. 295–314. | Sheppard, S 2004, Unravelling the complexity of the Gascoyne Complex, in GSWA 2004 extended abstracts: promoting the prospectivity of Western Australia: Geological Survey of Western Australia, Record 2004/5, p. 26–28. View Reference | Sheppard, S 2005, Does the ca. 1800 Ma Capricorn orogeny mark collision of the Yilgarn and Pilbara Cratons?, in Supercontinents and Earth Evolution Symposium 2005 - program and abstracts edited by Wingate, MTD and Pisarevsky, SA: IGCP 509 inaugural meeting, Fremantle, Western Australia, 26-30 September 2005: Geological Society of Australia and Promaco Conventions Pty Ltd, Canning Bridge, WA; GSA Abstracts no. 81, p. 29. | Sheppard, S, Bodorkos, S, Johnson, SP, Wingate, MTD and Kirkland, CL 2010, The Paleoproterozoic Capricorn Orogeny: Intracontinental reworking not continent-continent collision: Geological Survey of Western Australia, Report 108, 33p. View Reference | Sheppard, S and Swager, CP 1999, Geology of the Marquis 1:100 000 sheet: Geological Survey of Western Australia, 1:100 000 Geological Series Explanatory Notes, 21p. View Reference | Thorne, AM and Seymour, DB 1991, Geology of the Ashburton Basin, Western Australia: Geological Survey of Western Australia, Bulletin 139, 141p. View Reference | Tyler, IM and Thorne, AM 1990, The northern margin of the Capricorn Orogen, Western Australia — an example of an early Proterozoic collision zone: Journal of Structural Geology, v. 12, p. 685–701. | Wingate, MTD, Kirkland, CL, Bodorkos, S, Groenewald, PB and Sheppard, S 2010a, 187403.1: quartzite, Robinson Bore; Geochronology Record 862: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Wingate, MTD, Kirkland, CL, Bodorkos, S and Sheppard, S 2010b, 184160.1: psammitic schist, Weedarrah Homestead; Geochronology Record 863: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Wingate, MTD, Kirkland, CL and Johnson, SP 2011, 190662.1: gneissic metamonzogranite, Recovery Well; Geochronology Record 1005: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Wingate, MTD, Kirkland, CL, Johnson, SP and Sheppard, S 2012, 190660.1: metamonzogranite, Midway Bore; Geochronology Record 1036: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Wingate, MTD, Kirkland, CL, Thorne, AM and Johnson, SP 2014, 169885.1: biotite granodiorite, Stuarts Well; Geochronology Record 1208: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Wingate, MTD, Lu, Y and Fielding, IO 2017b, 219522.1: felsic volcanic rock, Koonong Pool; Geochronology Record 1369: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Wingate, MTD, Lu, Y, Fielding, IO and Johnson, SP 2017c, 219526.1: felsic volcanic rock, Bali Lo deposit; Geochronology Record 1370: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference | Wingate, MTD, Lu, Y, Kirkland, CL and Johnson, SP 2017a, 188974.1: metamonzogranite, Mount James homestead; Geochronology Record 1362: Geological Survey of Western Australia, <www.dmpe.wa.gov.au/geochron>. View Reference |
| | | | Recommended reference for this publication | Johnson, SP, Sheppard, S, Thorne, AM and Korhonen, FJ 2022, Capricorn Orogeny D2n/M2n (CCD2): 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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