This record presents new Sensitive High Resolution Ion MicroProbe (SHRIMP) U– Pb zircon results for eighteen samples from the Cairns, Cape York and Georgetown regions in Queensland. Samples from the Cairns region comprise one granite and one microgranite. Eight samples from the Cape York region and three from the Georgetown region comprise Paleozoic igneous rocks, all but one of which are part of the Carboniferous to Permian Kennedy Igneous Association. Of particular interest are the results for two rhyolitic intrusions from the Coen Inlier that are host to gold mineralisation and gave ages of approximately 280 Ma. These results are supported by similar ages reported by Kositcin et al. (2016), also from felsic dykes spatially associated with gold mineralisation. Together, they suggest a widespread, early-Permian gold (Kungurian) event in this region. The results for two felsic dykes spatially associated with gold mineralisation much farther to the south in the Georgetown region, also gave similar early-Permian ages. The geochronology of five metamorphic rocks from the Cape York region, which were analysed in support of the Coen–Cape Weymouth geology mapping project has resulted in all samples being reassigned to other formations. The work contained in this report was carried out under the auspices of the National Collaborative Framework (NCF) between Geoscience Australia and the Geological Survey of Queensland. The data and age interpretations are also available in Geoscience Australia’s Geochronology Delivery database (http://www.ga.gov.au/geochron-sapub-web/). <b>Bibliographic Reference: </b>CROSS, A.J., DHNARAM, C., BULTITUDE, R.J., BROWN, D.D., PURDY, D.J. & VON GNIELINSKI, F.E., 2019. Summary of results. Joint GSQ–GA geochronology project: Cairns, Cape York and Georgetown regions, 2015–2016. <i>Queensland Geological Record</i> <b>2019/01</b>.

New SHRIMP U-Pb zircon ages from the New England Orogen, New South Wales July 2014-June 2015

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.

The Thomson Orogen of eastern Australia is a major component of the Tasmanides and has historically been poorly understood and overlooked for exploration due to extensive sedimentary cover including the Eromanga Basin. To further understanding and encourage exploration of this area, Geoscience Australia, the Geological Survey of Queensland and the Geological Survey of New South Wales (NSW) have undertaken a major multidisciplinary geoscientific programme in the southern Thomson Orogen (STO) as a part of the UNCOVER initiative. A major outcome of this project has been the completion of twelve stratigraphic diamond drill holes between 2016 and 2017. SHRIMP U–Pb zircon dating of magmatic and metasedimentary rocks intersected by the boreholes provide new insights into the geological evolution and mineral prospectivity of this region. Geochronology of three intrusive rocks intersected by new boreholes in the NSW part of STO have late Silurian ages of ~425 Ma (Tongo 1), ~421 Ma (Janina 1) and ~421 Ma (Congararra 1). The age of the granodiorite intersected by Tongo 1 is within uncertainty of the intrusion-related Mo-W and later Au-base metal mineralisation at the Cuttaburra and F1 prospects located ~20 km southeast of the Tongo 1 borehole. Additionally, previously unknown volcanic events have been revealed by a dacitic ignimbrite (~387 Ma) in borehole GSQ Eulo 2 (Queensland) and a rhyolite (~395 Ma) in borehole, Milcarpa 1 (NSW). Detrital zircon geochronology has also played an important role in characterising undercover units such as the Werewilka Formation and Nebine Metamorphics, interpreted from geophysical data sets. This abstract was submitted to and presented at the 2018 Australian Geoscience Council Convention (AGCC) (https://www.agcc.org.au/)

<p>The Isotopic Atlas of Australia is one of the fundamental datasets in Geoscience Australia (GA)’s Exploring for the Future program. It is underpinned by a nationwide coverage of high-quality U-Th-Pb radiometric dates, mostly determined by Sensitive High Resolution Ion Micro Probe (SHRIMP). For the past decade, GA and the international SHRIMP community have relied on SQUID 2.50 software to process isotopic data acquired by SHRIMP for U-Th-Pb geochronology. However, SQUID 2.50 is obsolete because of dependency on Excel 2003, which is unsupported by Microsoft and will not operate on Windows 10. As a result, GA collaborated with the Cyber Infrastructure Research and Development Laboratory for Earth Sciences (CIRDLES.org) at the College of Charleston (USA) to redeploy SQUID 2.50 algorithms in an open-source, platform-independent and freely available Java application (Squid3). Squid3 replicates (rather than seeking to enhance) SQUID 2.50 logic and arithmetic, with substantial improvements in flexibility and interactivity. In this paper, we review documentation detailing widely trusted but little-known SQUID 2.50 algorithms and provide an overview of Squid3, focusing on the implementation and improvement of SQUID 2.50 functionality. The beta version of Squid3 is capable of end-to-end U-Th-Pb data processing, from ingestion of raw SHRIMP .xml files, through finalised summary calculations, to reporting of data arrays suitable for visualisation via packages such as Isoplot, Topsoil and IsoplotR. In production, Squid3 will enable users to sever links with Excel 2003, while ensuring the sustainability, reliability and relevance of SHRIMP data. <p><b>Citation:</b> Bodorkos, S., Bowring, J.F., and Rayner, N.M., 2020. Squid3: Next-generation data processing software for Sensitive High Resolution Ion Micro Probe (SHRIMP). In: Czarnota, K., Roach, I., Abbott, S., Haynes, M., Kositcin, N., Ray, A. and Slatter, E. (eds.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, 1–4.

Database containing analytical data and interpretations from the Geoscience Geoscience (GA) geochronology program. Includes some legacy methods and externally sourced data. A collection of analytical data to support geochronology data or ages used in other reporting and publications.

This Record presents new zircon U-Pb geochronological data, obtained using a Sensitive High Resolution Ion MicroProbe (SHRIMP), and thin section descriptions for four samples of plutonic and sedimentary rocks from the Captains Flat 1:50, 000 special map sheet, Eastern Lachlan 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 2012 and 2013. The four samples (Table 1.1 and Figure 1.1) were collected from CANBERRA (small and large capitals refer to map sheet names in the 1:100 000 and 1:250 000 Topographic Series respectively); one sample from CANBERRA (northcentral CANBERRA), two from MICHELAGO (southcentral CANBERRA) and one from ARALUEN (southcentral CANBERRA).

<p>This record presents new zircon and titanite U–Pb geochronological data, obtained via Sensitive High Resolution Ion Microprobe (SHRIMP) for twelve samples of plutonic and volcanic rocks from the Lachlan Orogen and the New England Orogen, and two samples of hydrothermal quartz veins from the Cobar region. Many of these new ages improve existing constraints on the timing of mineralisation in New South Wales, 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 Collaborative Framework (NCF) agreement. The results herein (summarised in Table 1.1 and Table 1.2) correspond to zircon and titanite U–Pb SHRIMP analysis undertaken on GSNSW mineral systems projects for the reporting period July 2016–June 2017. Lachlan Orogen <p>The Lachlan Orogen samples reported herein are sourced from operating mines, active prospects, or regions with historical workings. The new dates constrain timing of mineralisation by dating the units which host or crosscut mineralisation, thereby improving understanding of the mineralising systems, and provide stronger constraints for mineralisation models. <p>In the eastern Lachlan Orogen, the new dates of 403.9 ± 2.6 Ma for the Whipstick Monzogranite south of Bega, and 413.3 ± 1.8 Ma for the Banshea Granite north of Goulburn both provide maximum age constraints for the mineralisation they host (Whipstick gold prospect and Ruby Creek silver prospect, respectively). At the Paupong prospect south of Jindabyne, gold mineralisation is cut by a dyke with a magmatic crystallisation age of 430.9 ± 2.1 Ma, establishing a minimum age for the system. <p>The 431.1 ± 1.8 Ma unnamed andesite and the 428.4 ± 1.9 Ma unnamed felsic dyke at the Dobroyde prospect 10 km north of Junee are just barely distinguishable in age, in the order that is supported by field relationships. The andesite is the same age as the c. 432 Ma Junawarra Volcanics but has different geochemical composition, and is younger than the c. 437 Ma Gidginbung Volcanics. The two unnamed units pre-date mineralisation, and are consistent with Pb-dating indicating a Tabberaberran age for mineralisation at the Dobroyde gold deposit. <p>Similarly, the 430.5 ± 3.4 Ma leucogranite from Hickory Hill prospect (north of Albury) clarifies that this unit originally logged as Jindera Granite (since dated at 403.4 ± 2.6 Ma) is instead affiliated with the nearby Mount Royal Granite, which has implications for the extent of mineralisation hosted within this unit. <p>Cobar Basin <p>Titanite ages of 382.5 ± 2.6 Ma and 383.4 ± 2.9 Ma from hydrothermal quartz veins that crosscut and postdate the main phase of mineralisation at the Hera mine in the Cobar region constrain the minimum age for mineralisation. These ages are indistinguishable from a muscovite age of 381.9 ± 2.2 Ma interpreted to be related to late- or post-Tabberaberan deformation event, and these results indicate that mineralisation occurred at or prior to this deformation event. <p>New England Orogen <p>The new ages from granites of the New England Orogen presented in this record aid in classification of these plutons into various Suites and Supersuites, and these new or confirmed relationships are described in detail in Bryant (2017). Many of these plutons host mineralisation, so the new ages also provide maximum age constraints in the timing of that mineralisation. <p>The 256.1 ± 1.3 Ma age of the Deepwater Syenogranite 40 km north of Glen Innes indicates that it is coeval with the 256.4 ± 1.6 Ma (Black, 2006) Arranmor Ignimbrite Member (Emmaville Volcanics) that it intrudes, demonstrating that both intrusive and extrusive magmatism was occurring in the Deepwater region at the same time. The 252.0 ± 1.2 Ma age for the Black Snake Creek Granite northeast of Tenterfield is consistent with its intrusive relationship with the Dundee Rhyodacite (254.34 ± 0.34 Ma; Brownlow et al., 2010). Similarly, the 251.2 ± 1.3 Ma age for the Malara Quartz Monzodiorite southeast of Tenterfield is consistent with field relationships that demonstrate that it intrudes the Drake Volcanics (265.3 ± 1.4 Ma–264.4 ± 2.5 Ma, Cross and Blevin, 2010; Waltenberg et al., 2016). <p>The 246.7 ± 1.5 Ma Cullens Creek Granite north of Drake was dated in an attempt to provide a stronger age constraint on mineral deposits that also cut the Rivertree and Koreelan Creek plutons (249.1 ± 1.3 Ma and 246.3 ± 1.4 Ma respectively, Chisholm et al., 2014a). However, the new age is indistinguishable from the Koreelan Creek Granodiorite, and timing of mineralisation is not further constrained, but the new age demonstrates a temporal association between the Cullens Creek and Koreelan Creek plutons. <p>The 239.1 ± 1.2 Ma age for the Mann River Leucogranite west of Grafton is indistinguishable in age from plutons in the Dandahra Suite and supports its inclusion in this grouping. The new age also constrains the timing of the distal part of the Dalmorton Gold Field, and implies that the gold vein system postdates the Hunter-Bowen orogeny. <p>The 232.7 ± 1.0 Ma Botumburra Range Monzogranite east of Armidale is younger than most southern New England granites, but this age is very consistent with the Coastal Granite Association (CGA), and the new age, along with the previously noted petrographic similarities (Leitch and McDougall, 1979) supports incorporation of the Botumburra Range Monzogranite into the Carrai Supersuite of the CGA (Bryant, 2017).

This Record presents six previously unpublished U–Pb SHRIMP zircon geochronological results from the Aileron Province in the Northern Territory. The data was collected to investigate the timing of localised and poorly documented granulite facies high-T, low-P metamorphism across isolated outcrops in the central and western Aileron Province. The study was also designed to test the maximum deposition ages of the metasedimentary rocks across this large area, and whether the data are consistent with the samples being high-grade equivalents of the Lander Rock Formation. <b>Bibliographic Reference:</b> Kositcin N, and Scrimgeour IR, 2020. Summary of results: Joint NTGS–GA geochronology project: central and western Aileron Province. <i>Northern Territory Geological Survey</i>, <b>Record 2020-011</b>.