Australian Proterozoic orogenic belts are typically characterised by high-temperature, low-pressure, long-lived metamorphism and near-isobaric cooling. However, this is not the case for the Nimbuwah Domain, the easternmost part of the Pine Creek Orogen and part of the oldest core of the North Australian Craton. Here we present new field relationships, geochemical, metamorphic, SHRIMP zircon and monazite U-Pb age, and zircon Lu-Hf and whole-rock Sm-Nd isotopic data for the Nimbuwah Complex and metasedimentary rocks of the Cahill Formation that they intruded in the Nimbuwah Domain. On the basis of these data we propose a new tectonic model for the Paleoproterozoic evolution of the Pine Creek Orogen. SHRIMP zircon U-Pb age data show that granitic to dioritic plutons of the Nimbuwah Complex were emplaced from 1871-1857 Ma at - 9.2 kbar and 650-C into thickened crust during D2-D3 west-directed thrusting and folding. This is termed the Nimbuwah Event. The Nimbuwah Complex was formed by partial melting of Neoarchean granites in the mid to lower crust and mixing with a juvenile magma component. The overthickened crust underwent extensional uplift to <5 kbar by 1855 Ma, constrained by monazite growth during garnet breakdown associated with syn- to late-D2 decompression. We propose that crustal thickening and magmatism occurred in response to collision of Neoarchean to Paleoproterozoic basement of the Pine Creek Orogen (the over-riding plate) with an unknown collider, now concealed beneath younger cover to the east. Exhumation of at least a 15 km crustal thickness within only a few million years indicates a short period of collisional orogenesis, consistent with the observed metamorphic evidence for a low thermal gradient during crustal thickening. Tectonic uplift and erosion of the Nimbuwah Complex fed the retro-arc Cosmo Supergroup and possibly other Paleoproterozoic successions of the North Australian Craton that are dominated by c. 1870 Ma detritus. The low thermal gradient in overthickened crust, which is unusual for Proterozoic Australia, might be a consequence of collision between relatively cool, rigid Archean blocks.

This Record presents new zircon U-Pb geochronological data, obtained using a Sensitive High Resolution Ion MicroProbe (SHRIMP) for five samples of plutonic and volcanic rocks from the central Lachlan Orogen and the Thomson Orogen, New South Wales. The work was carried out under the auspices of the National Geoscience Accord, as a component of the collaborative Geochronology Project between the Geological Survey of New South Wales (GSNSW) and Geoscience Australia (GA) during the reporting periods 2011-2012.

<div>This record presents nine new zircon and titanite U–Pb geochronological data, obtained via Sensitive High Resolution Ion Microprobe (SHRIMP) for seven samples of plutonic rocks from the Lachlan Orogen and the Cobar Basin, plus one garnet-bearing skarn vein from the Cobar region. Many of these new ages improve existing constraints on the timing of mineralisation in the Cobar Basin, as part of an ongoing Geochronology Project (Metals in Time), conducted by the Geological Survey of New South Wales (GSNSW) and Geoscience Australia (GA) under a National Collaboration Framework (NCF) agreement. The results herein (summarised in Table 1.1) correspond to zircon and titanite U–Pb SHRIMP analysis undertaken on GSNSW Mineral Systems projects over July 2017–June 2019.</div><div><br></div><div>Our new data establish an episode of c. 427–425 Ma I-type plutonism, coeval with regional S-type granites, which marginally predated opening of the Cobar Basin. Widespread S-type and high-level I-type magmatism accompanied 423–417 Ma basin development. At least two episodes of skarn-related mineralisation are recognised in the southern Cobar Basin: c. 387 Ma (from pre-mineralisation skarn veins) at Kershaws prospect, and c. 403 Ma at the adjacent Hera mine (Fitzherbert et al., 2021).</div><div><br></div><div>Three intrusive rocks were dated at the Norma Vale prospect in the southwestern Cobar Basin, where calcic iron-copper skarn mineralisation is thought to have been caused by I-type but compositionally complex high-level intrusive rocks emplaced along a northeast-oriented fault related to the nearby Rookery Fault (Fitzherbert et al., 2017). A 423 ± 8 Ma I-type quartz diorite potentially constrains the timing of skarn mineralisation, but is indistinguishable in age from a 421.3 ± 3.0 Ma S-type cordierite-biotite granite and a 417.5 ± 3.3 Ma coarse-grained S-type granite, both from deeper in the same drillhole. These results suggest that at least some of the coeval S-type and high-level I-type magmatic activity accompanying opening of the Cobar Basin was associated with early mineralisation, although skarn-forming processes regionally are complex and episodic (Fitzherbert et al., 2021).</div><div><br></div><div>In the Cobar mining belt, our new date of 422.8 ± 2.8 Ma for I-type rhyolitic porphyry at Carissa Shaft (which is one of the southernmost high-level intrusions associated with the Perseverance and Queen Bee orebodies) is coeval with the 423.2 ± 3.5 Ma ‘Peak rhyolite’ (Black, 2007), but marginally older than the 417.6 ± 3.0 Ma Queen Bee Porphyry (Black, 2005). At Gindoono, a 423.0&nbsp;±&nbsp;2.6&nbsp;Ma unnamed dacitic porphyry intruded and hornfelsed the undated I-type Majuba Volcanics, thereby establishing a minimum age for that unit.</div><div><br></div><div>East of Cobar, the I-type Wild Wave Granodiorite intruded the Ordovician Girilambone Group, but was exhumed and eroded to form clasts within pebble conglomerates of the lowermost Cobar Basin. Its new U–Pb SHRIMP zircon age of 424.1 ± 2.8 Ma constrains the timing of I-type plutonism which marginally predated formation of the Cobar Basin. A similar zircon age of 426.7 ± 2.3 Ma was obtained from the concealed Fountaindale Granodiorite north of Condoblin, indicating that this I-type pluton is coeval with the nearby and much larger c. 427 Ma S-type Erimeran Granite. Titanite from the same sample of Fountaindale Granodiorite yielded an age of 421.6 ± 2.7 Ma, which is significantly younger than the zircon age, and is interpreted to constrain the timing of ‘deuteric’ (chlorite-albite-epidote-titanite-sericite-carbonate) alteration during post-magmatic hydrothermal activity (e.g. Blevin, 2003b).</div><div><br></div><div>A garnet-bearing skarn vein at Kershaws prospect, adjacent to the Hera orebody (Fitzherbert et al., 2021), predates the main phase of mineralisation, and yielded a titanite age of 387.2 ±&nbsp;6.2&nbsp;Ma. This indicates that the skarn-forming hydrothermal event at Kershaws prospect is significantly younger than the c. 403 Ma age for the main mineralising event at Hera mine (Fitzherbert et al., 2021).</div>

The fundamental geological framework of the concealed Paleoproterozoic East Tennant area of northern Australia is very poorly understood, despite its relatively thin veneer of Phanerozoic cover and its position along strike from significant Au–Cu–Bi mineralisation of the Tennant Creek mining district within the outcropping Warramunga Province. We present 18 new U–Pb dates, obtained via Sensitive High Resolution Ion Micro Probe (SHRIMP), constraining the geological evolution of predominantly Paleoproterozoic metasedimentary and igneous rocks intersected by 10 stratigraphic holes drilled in the East Tennant area. The oldest rocks identified in the East Tennant area are two metasedimentary units with maximum depositional ages of ca. 1970 Ma and ca. 1895 Ma respectively, plus ca. 1870 Ma metagranitic gneiss. These units, which are unknown in the nearby Murphy Province and outcropping Warramunga Province, underlie widespread metasedimentary rocks of the Alroy Formation, which yield maximum depositional ages of 1873–1864 Ma. While parts of this unit appear to be correlative with the ca. 1860 Ma Warramunga Formation of the Warramunga Province, our data suggest that the bulk of the Alroy Formation in the East Tennant area is slightly older, reflecting widespread sedimentation at ca. 1870 Ma. Throughout the East Tennant area, the Alroy Formation was intruded by voluminous 1854–1845 Ma granites, contemporaneous with similar felsic magmatism in the outcropping Warramunga Province (Tennant Creek Supersuite) and Murphy Province (Nicholson Granite Complex). In contrast with the outcropping Warramunga Province, supracrustal rocks equivalent to the 1845–1810 Ma Ooradidgee Group are rare in the East Tennant area. Detrital zircon data from younger sedimentary successions corroborate seismic evidence that at least some of the thick sedimentary sequences intersected along the southern margin of the recently defined Brunette Downs rift corridor are possible age equivalents of the ca. 1670–1600 Ma Isa Superbasin. Our new results strengthen ca. 1870–1860 Ma stratigraphic and ca. 1850 Ma tectono-magmatic affinities between the East Tennant area, the Murphy Province, and the mineralised Warramunga Province around Tennant Creek, with important implications for mineral prospectivity of the East Tennant area. Appeared in Precambrian Research Volume 383, December 2022.

To test existing geological interpretations and the regional stratigraphic relationships of the Carrara Sub-basin with adjacent resource-rich provinces, the deep stratigraphic drill hole NDI Carrara 1 was located on the western flanks of the Carrara Sub-basin, on the seismic line 17GA-SN1. The recovery of high quality near-continuous core from the Carrara Sub-basin, in concert with the spectrum of baseline analytical work being conducted by Geoscience Australia through the EFTF program, as well as other work by government and university researchers is greatly improving our understanding of this new basin. While recently published geochemistry baseline datasets have provided valuable insight into the Carrara Sub-basin, the age of the sedimentary rocks intersected by NDI Carrara 1 and their chronostratigraphic relationships with adjacent resource rich regions has remained an outstanding question. In this contribution, we present new sensitive high-resolution ion microprobe (SHRIMP) geochronology results from NDI Carrara 1 and establish regional stratigraphic correlations to better understand the energy and base-metal resource potential of this exciting frontier basin in northern Australia.

NDI Carrara 1 is a deep stratigraphic drill hole (~1751m) completed in 2020 as part of the MinEx CRC National Drilling Initiative (NDI) in collaboration with Geoscience Australia and the Northern Territory Geological Survey. It is the first test of the Carrara Sub-basin, a depocentre newly discovered in the South Nicholson region based on interpretation from seismic surveys (L210 in 2017 and L212 in 2019) recently acquired as part of the Exploring for the Future program. The drill hole intersected approximately 1100 m of Proterozoic sedimentary rocks uncomformably overlain by 630 m of Cambrian Georgina Basin carbonates. This report presents SHRIMP U-Pb zircon geochronology on 10 volcaniclastic rocks taken from NDI Carrara 1.

This Record presents data collected in September 2019 as part of the ongoing Northern Territory Geological Survey–Geoscience Australia (NTGS–GA) SHRIMP geochronology project under the National Collaborative Framework (NCF) agreement and Geoscience Australia's Exploring for the Future (EFTF) Program. Two new U–Pb SHRIMP zircon geochronological results derived from two samples of the Balbirini Dolostone (southern McArthur Basin, Northern Territory) are presented herein. The Balbirini Dolostone is part of the early Mesoproterozoic Nathan Group, and is a thick unit of interbedded dolostone and dolomitic siliciclastic rocks that include evaporitic redbeds. The two samples were collected in June 2019 from the type section of the Balbirini Dolostone in southern BAUHINIA DOWNS (MALLAPUNYAH). <b>Bibliographic Reference:</b> Kositcin N, and Munson TJ, 2020. Summary of results. Joint NTGS–GA geochronology project: Balbirini Dolostone, southern McArthur Basin, June 2019–September 2019. <i>Northern Territory Geological Survey</i>, <b>Record 2020-002</b>.

This Record presents data collected in July–August 2020 as part of the ongoing Northern Territory Geological Survey–Geoscience Australia SHRIMP geochronology project under the National Collaboration Framework agreement and Geoscience Australia's Exploring for the Future Program. New U–Pb SHRIMP zircon geochronological results derived from eight sedimentary samples from the western Amadeus Basin in the Northern Territory are presented herein. Detrital zircon U–Pb ages were determined from four samples of the Winnall Group: three samples of the Liddle Formation and one of the Puna Kura Kura Formation. Zircon U–Pb ages were also determined from two samples of the Pertaoorrta Group (Cleland Sandstone and Tempe Formation), one sample of the Larapinta Group (Stairway Sandstone) and one sample of the Mereenie Sandstone. <b>Bibliographic Reference:</b> Kositcin N, Verdel C, Normington VJ and Simmons JM, 2021. Summary of results. Joint NTGS–GA geochronology project: western Amadeus Basin, July–August 2020. <i>Northern Territory Geological Survey, Record</i> <b>2021-002</b>.

An important finding of this study is the presence of Williams-Naraku Batholith ages (i.e. ca 1500 Ma) east and (well) north of the currently known extent. Sample 2804770/DPMI013 is a leucocratic biotite granite collected from unnamed unit PLg/k ca 30 km southwest of Burke and Wills Roadhouse at the far northern outcropping extent of the Mary Kathleen Domain. This unit intrudes the Corella Formation and Boomarra Metamorphics as small pods and dykes that likely represent the upper portions of a larger pluton. The results from this sample are complex but indicate a minimum crystallisation age of 1500 ± 6 Ma. This is within error of units assigned to the Williams and Naraku Batholiths (e.g. Mavis Granodiorite, Malakoff Granite, Wimberu Granite – see geochronology compilation of Jones et al., 2018). A similar but more certain age of 1511 ± 4 Ma was determined for an unnamed amphibole granite farther south near Kajabbi (2804772/DPMI049b). It is likely that this intrusion also represents the upper parts of a pluton that is more extensive at depth. Together, these two new ages greatly expand the known extent of magmatism at ca 1500 Ma. The Mount Godkin Granite forms a prominent, topographically high range ca 45km northwest of Cloncurry. It intrudes the Corella Formation and has a distinct ellipsoid mapped extent. On the basis of geochemistry, Budd et al. (2001) included the Mount Godkin Granite in the Burstall Suite. The crystallisation age reported here (1739 ± 3 Ma) for sample 2804771/DPMI041 is within error of the most recent published ages from the Burstall Granite and Lunch Creek Gabbro (i.e. 1740 ± 3 Ma, 1737 ± 3 Ma, 1739 ± 3 Ma; Neumann et al., 2009) confirming broadly synchronous emplacement. We also sampled a fine-grained, leucocratic and miarolitic biotite granite from the far northern tip of the Burstall Granite (mapped as subunit l). Despite being lithologically and texturally distinct from the main body of Burstall Granite, this sample (2804773/DPMI054) yielded a similar crystallisation age (1736 ± 4 Ma) to the main Burstall Granite and Lunch Creek Gabbro bodies (Neumann et al., 2009). A lithologically similar, unfoliated, miarolitic leucogranite was sampled from Exco Resources drill core EMCDD094 (534.85–536.07 m) at Mount Colin mine near the contact between the Burstall Granite and Corella Formation. In drill core, this granite contains large xenoliths of Corella Formation and locally transitions to a crystallised hydrothermal phase. It appears intimately associated with copper mineralisation and the crystallisation age of 1737 ± 3 Ma determined here (2804792/DPMI080) may be similar to the mineralisation age. The Myubee Igneous Complex and Overlander Granite intrude the Corella Formation in the southern part of the Mary Kathleen Domain. They were thought to have been emplaced at about the same time as the nearby Revenue Granite, the Mount Erle Igneous Complex farther south, and the Burstall Granite to the north, based on lithological and chemical similarities (e.g., Bultitude et al., 1978, 1982; Blake et al., 1984). These last three units have yielded U–Pb zircon (SHRIMP) ages in the 1735–1740 Ma range (Neumann et al., 2009; Geoscience Australia, 2011; Kositcin et al., 2019). However, Bierlein et al. (2011) reported slightly younger SHRIMP zircon emplacement ages in the 1718–1722 Ma range for parts of the Revenue Granite and Mount Erle Igneous Complex, suggesting the units are composite. The 1740 ± 5 Ma age yielded by the Overlander Granite as part of the current study is similar to ages recorded for the units listed above and, therefore, supports the interpretations of earlier workers. The granite is associated spatially with several small Cu–Au deposits in nearby country rocks (Corella Formation) including the Overlander group of mines (abandoned) and prospects, and the Andy’s Hill (Cu–Au–Co–La) and Scalper (Cu–Au) prospects (Denaro et al., 2003), but a genetic relationship between the granite and mineralisation has yet to be unequivocally demonstrated. Granite of the Myubee Igneous Complex yielded a slightly younger age of 1727 ± 5 Ma. We interpret this as a minimum age for igneous crystallisation of the granite, because most of the SHRIMP zircon analyses preserve evidence of post-crystallisation isotopic disturbance. However, it does support the conclusion of Passchier (1992) who deduced that the Myubee Igneous Complex is slightly younger than the nearby Revenue Granite, based on structural criteria. According to Passchier D1 (local) structures in the Revenue Granite are not present in the Myubee Igneous Complex. The significance of the anomalously young SHRIMP, zircon age of 1722 ± 5 Ma subsequently reported by Bierlein et al. (2011) for the Revenue Granite has yet to be resolved. The dated sample of Wimberu Granite is from a relatively small lobe, separated from the main outcrop area to the east by an extensive cover of younger Georgina Basin rocks. The lobe is located ~11 km east of the Pilgrim Fault Zone, which marks the eastern boundary of the Mary Kathleen Domain. The analysed sample yielded a U–Pb zircon age of 1518 ± 5 Ma, which is similar to the U–Pb (SHRIMP) zircon ages reported previously for different parts of the main body of Wimberu Granite east of Devoncourt homestead—namely 1508 ± 4 Ma (Page & Sun, 1998) and 1512 ± 4 (Pollard & McNaughton, 1997). <b>Bibliographic Reference: </b>Bodorkos, S., Purdy, D.J., Bultitude, R.J., Lewis, C.J., Jones, S.L., Brown, D.D. and Hoy, D., 2020. Summary of Results. Joint GSQ–GA Geochronology Project: Mary Kathleen Domain and Environs, Mount Isa Inlier, 2018–2020. <i>Queensland Geological Record</i><b> 2020/04</b>.

This Record presents data collected in March 2021 as part of the ongoing Northern Territory Geological Survey–Geoscience Australia (NTGS–GA) SHRIMP geochronology project under the National Collaborative Framework (NCF) agreement and Geoscience Australia's Exploring for the Future Program. New U–Pb SHRIMP zircon geochronological results derived from two drillhole samples of igneous and meta-igneous material from basement to the Amadeus Basin in the Northern Territory are presented herein. <b>Bibliographic Reference:</b> Kositcin N, Verdel C and Edgoose CJ, 2022. Summary of results. Joint NTGS–GA geochronology project: Crystalline basement intersected by the Mount Kitty 1 and Magee 1 drillholes south of Alice Springs, March 2021. <i>Northern Territory Geological Survey</i>, <b>Record 2022-002</b>.