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Zircon LA-ICPMS Hf and SIMS O isotopic data for granitic gneiss of the Billabong Complex, Tanami Region

Details:

Title

Zircon LA-ICPMS Hf and SIMS O isotopic data for granitic gneiss of the Billabong Complex, Tanami Region

Creator

Whelan, JA; Woodhead, JD; Cliff, J; Whelan, JA; Woodhead, JD; Cliff, J

Issued by

Northern Territory Geological Survey; Northern Territory Geological Survey

Collection

E-Publications; E-Books; PublicationNT; NTGS Record

Date

2014; 2014

Location

Tanami Region

Abstract

This record presents new laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) Lu Hf isotope results and secondary-ion mass spectrometry (SIMS) O isotope data for zircon from a granitic gneiss of the Billabong Complex, Tanami Region.'; This record presents new laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) Lu Hf isotope results and secondary-ion mass spectrometry (SIMS) O isotope data for zircon from a granitic gneiss of the Billabong Complex, Tanami Region.'

Notes

Made available via the Publications (Legal Deposit) Act 2004 (NT); Available from GEMIS - Geoscience Exploration and Mining Information System; Made available via the Publications (Legal Deposit) Act 2004 (NT)

Language

English

Subject

Geochronology; Isotope Geochemistry; Tanami Region

Publisher name

Northern Territory Government; Northern Territory Government

Place of publication

Darwin

Series

NTGS Record

Volume

2014-002

File type

application/pdf

ISBN

9780724572717 (CD-ROM); 9780724572724 (Web); 9780724572717 (CD-ROM); 9780724572724 (Web)

ISSN

1443-1149; 1443-1149

Use

Attribution International 4.0 (CC BY 4.0)

Copyright owner

Northern Territory Government; Northern Territory Government

License

https://creativecommons.org/licenses/by/4.0/; https://creativecommons.org/licenses/by/4.0/

Related links

https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/82465 [GEMIS]; https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/82465

Parent handle

https://hdl.handle.net/10070/794234; https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/82465

Citation address

https://hdl.handle.net/10070/794255

Page content

5 Grain 206Pbc (%) U (ppm) 232Th/ 238U 206Pb*/ 238U (%) 207Pb*/ 206Pb* (%) 207Pb/ 206Pb Age (Ma) (1) dis% 176Hf/ 177Hf 2 176Lu/ 177Hf 2 Hf Hfi TDM 18O 1 267.57.1.1 -0.01 129 0.48 2.086 1.4 0.166 0.5 2521 8 0 0.281 0.000 0.000 0.000 -3.1 0.281 3.2 4.5 0.1 267.51.1.1 0.01 105 1.00 2.081 1.5 0.166 0.5 2520 9 0 267.12.1.1 0.03 96 0.78 2.117 1.5 0.166 0.6 2520 9 1 0.281 0.000 0.001 0.000 -0.4 0.281 3.0 5.6 0.2 Metamorphic (n = 2) 267.53.1.1 0.01 548 0.17 2.186 1.1 0.162 0.2 2481 4 3 0.281 0.000 0.001 0.000 2.6 0.281 3 3.8 0.2 267.41.1.1 0.01 201 0.51 2.133 1.3 0.162 0.4 2479 7 0 0.281 0.000 0.002 0.000 6.0 0.281 3 5.2 0.2 Metamorphic/recrystallised grain (n = 1) 267.60.1.1 0.03 1515 0.08 3.222 1.2 0.110 0.2 1805 3 4 0.281 0.000 0.002 0.000 -18.5 0.281 4 6.7 0.2 >5% discordant and/or high common Pb (n = 22) 267.26.1.1 20.84 117 1.42 2.443 4.7 0.189 24.0 2729 390 22 267.21.2.1 0.80 200 0.80 2.438 2.4 0.168 0.8 2542 13 15 267.50.1.1 0.40 418 0.79 2.236 1.1 0.167 0.4 2523 7 7 267.71.1.1 1.50 400 0.67 2.375 1.4 0.166 2.2 2520 36 12 267.43.1.1 1.24 422 0.66 2.246 1.1 0.166 0.6 2520 10 7 267.70.1.1 0.59 403 0.38 2.247 1.3 0.166 1.0 2515 17 7 267.23.1.1 3.06 384 0.75 2.463 1.8 0.166 2.9 2513 48 15 267.37.1.1 0.13 351 0.65 2.240 1.2 0.165 0.6 2507 10 6 267.9.1.1 1.43 393 1.18 2.606 2.4 0.164 0.5 2500 8 19 267.68.1.1 0.35 1025 1.54 2.298 1.9 0.164 0.4 2499 7 8 267.6.1.1 1.58 235 1.00 2.259 1.2 0.164 0.9 2499 16 7 267.32.1.1 0.07 423 1.01 2.243 1.1 0.164 0.4 2497 7 6 267.67.1.1 1.23 1374 0.49 2.215 1.2 0.161 0.3 2468 6 3 267.7.1.1 7.76 568 0.25 3.875 5.6 0.160 8.8 2455 149 44 267.52.1.1 0.99 305 0.34 2.902 1.2 0.160 0.5 2453 8 26 267.61.1.1 0.76 595 0.88 2.462 1.1 0.159 0.4 2444 7 12 267.13.1.1 5.99 545 1.74 3.587 2.0 0.159 4.4 2441 74 39 267.45.2.1 0.49 487 0.19 2.547 2.3 0.158 0.6 2429 10 14 267.14.1.1 0.93 464 0.64 3.211 1.1 0.155 0.5 2396 8 31 267.62.1.1 0.88 823 0.23 2.791 1.5 0.153 0.3 2380 5 20 267.73.1.1 0.32 536 0.12 4.599 10.6 0.128 5.8 2074 102 43 267.8.2.1 1.93 1319 0.06 3.907 2.8 0.109 3.5 1787 64 20 Excess error (n = 1) 267.54.1.1 0.03 389 0.60 2.151 1.5 0.171 4.0 2569 66 5 Table 1. Tabulated U-Pb SHRIMP, O SIMS and Hf LA-ICPMS data for Billabong Complex, NTGS MS11JAW001. U-Pb data from Kositcin et al (2013) (continued from previous page). report. Eighty analyses were collected on 74 individual zircon grains from sample MS11JAW001, 207Pb/206Pb ages for individual grains are provided in Table 1. Twentytwo analyses are more than 5% discordant (and/or have high Pbc (>0.5%), and one analysis has an excessive error. All 23 are removed from further interpretation. Kositcin et al (2013) report two possible interpretations based on the U-Pb data: Thirty-six concordant analyses from distinctive zircon cores form a single population with a weighted mean age of 2532 3 Ma (95% confidence, n = 36, MSWD = 1.19, probability = 0.21), which is interpreted to record an inherited population. Eighteen concordant analyses are from zircon rims surrounding inherited grains and lesser solitary zircon grains (with overall lower Th), which combine to yield a weighted mean age of 2510 4 Ma (95% confidence, n = 18, MSWD = 0.80, probability = 0.69). This is interpreted as the magmatic crystallisation age of this orthogneiss. However, it is equally feasible that the 2532 3 Ma age is recording the igneous crystallisation age of the gneiss (the unimodal population supports this) and the 2510 4 Ma age is recording metamorphic growth. This interpretation is just as significant, perhaps more so, in light of potential links with magmatic and metamorphic events in the Pine Creek Orogen. Further work, including O and Hf analysis, may help differentiate between these possible scenarios. Two analyses, yielding individual ages of 2481 4 Ma and 2479 7 Ma (1), were derived from distinctly different zircons they are small, transparent, colourless and have a weak CL response. They are interpreted as possibly being of metamorphic origin, suggesting that the granitic protolith experienced metamorphic crystallisation at ca 2480 Ma. Alternatively, they could also be interpreted as recording Pb loss. Interestingly, rocks in the Pine Creek Orogen are interpreted to have experienced recrystallisation/ metamorphism, with zircon rims recorded at 2498 14 Ma (Arrarra Gneiss, Carson et al 2010) and 2473 12 Ma (unnamed leucocratic gneiss, Worden et al 2006). One analysis, with low Th/U, returned an age of 1805 3 Ma (1). The mottled nature of its CL response could be consistent with recrystallisation. Although not conclusive, as only one grain of this age was recorded, it is


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