Age and tectonic significance of the Louth Volcanics

Dwyer et al. (2018). Supplementary Papers Australian Journal of Earth Sciences, 65, 1049–1069. https://doi.org/10.1080/08120099.2018.1469392

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Age and tectonic significance of the Louth Volcanics: implications

for the evolution of the Tasmanides of eastern Australia. R. C. Dwyera*, W. J. Collinsa,b, A. C. Hackc, R. Hegartyd and H. Huanga,e

aNSW Institute for Frontiers Geoscience, University of Newcastle, Newcastle, NSW 2308, Australia; bEarth Dynamics Research Group, Department of Applied Geology, Curtin University, GPO Box U1987, Perth, WA 6845, Australia; cDiscipline of Earth Sciences, School of Environmental and Life Sciences, Faculty of Science, The University of Newcastle, University Drive, Callaghan NSW 2308, Australia; dGeological Survey of New South Wales, NSW Department of Planning and Environment, PO Box 344 Hunter Region MC, NSW 2310, Australia; eNow at, Division of Tropical Environments and Societies, James Cook University, Townsville, QLD 4814, Australia [email protected]

SUPPLEMENTARY PAPERS

Australian Journal of Earth Sciences (2018) 65, 1049–1069. https://doi.org/10.1080/08120099.2018.1469392

Copies of Supplementary Papers may be obtained from the Geological Society of Australia's website (www.gsa.org.au), the Australian Journal of Earth Sciences website (www.ajes.com.au) or from the National Library of Australia's Pandora archive (http://nla.gov.au/nla.arc-25194).

Supplementary papers Table SM1. Sample locations, depths and repository location. Table SM2. Summary of petrographic characteristics of key samples. Table SM3. Geochemical and whole-rock εNd samples sources. Table SM4. Whole-rock geochemical data from this study. Table SM5. Whole-rock ɛNd data from this study. Table SM6. Summary of LA-ICP-MS U/Pb zircon results. Figure SM1. (a) TL and CL images of concordant Permo-Triassic aged zircons recovered from

PANGBH7-10 displaying the characteristic grain morphology of the alkaline group. Note the similarities in grain morphology and zoning between zircons from PANGBH7-10 and the two volcaniclastic sample PANGBH5-04 and PANGBH6-01. (b) CL images modified after Grime et al. (2009) displaying the characteristic zoning of zircons recovered from mafic rocks which is broadly similar to the zoning observed in zircons recovered from the alkaline group. All scale bars are 100 µm.


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Figure SM2. TL and CL images of zircons recovered from PANGBH5-04 and PANGBH6-01 displaying the characteristic grain morphology of the alkaline group. Note the similarities in grain morphology and zoning to zircons recovered from PANGBH7-10 suggesting these grains were potentially derived from a similar gabbroic host rock to PANGBH7-10. (a) TL and CL images of concordant Permo-Triassic aged zircons recovered from PANGBH6-01. (b) TL and CL images of concordant Permo-Triassic aged zircons recovered from PANGBH5-04. All scale bars are 100 mm.

Figure SM3. Probability density plots of temperatures obtained from Permo-Triassic aged zircons recovered from PANGBH5-04 and PANGBH6-01 (a) are broadly similar to those from mafic rocks (b) but show a wider temperature range and peaks not observed in the mafic datasets from Fu et al. (2008). When compared with the patterns of volcanic (c) and mafic rocks, the broader pattern potentially represents a mafic pattern superimposed over a volcanic one (Fu et al., 2008).

Figure SM4. Wetherill-type concordia diagrams and probability density plots of concordant data for additional samples from the Permo-Triassic alkaline group. (a) Sample NBHT1-05 underlying NBHT1-06. Both samples return the same emplacement/MDA. NBHT1-05 features a provenance signal similar to that of detrital samples from Louth and the NLO including a 415 ± 15 Ma, which is in error of the Early Devonian age of the calcalkaline Louth Volcanics. (b) Sample GETTY5/6-1-02. This was found within an alkaline breccia sequence but only returned discordant Permo-Triassic ages. Provenance signals are similar to samples from Louth and the NLO and include Devonian to Carboniferous ages suggesting incorporation of detrital components from the Lower Devonian Louth Volcanics and the Winduck/Mulga Downs Groups. (c) A large quantity of zircons were recovered for PANGBH7-01 but they were so fine (~ 20–30 mm) that analytical options were limited and returned mostly discordant results. This sample is located at the same approximate depth as PANGBH6-01 and appear to represent the same sequence of volcanogenic and volcaniclastic sedimentary rocks. The results from this samples are so limited that it is possible the youngest component was not analysed, and this age is considered unlikely to represent this unit’s true MDA. (d) Discordia regression of apatite data from the Getty Gabbro. Analysis of apatite grains separated from the Getty Gabbro did not return concordant ages but a discordia regression is suggestive of a Permian age. The precision is so poor that the only conclusion that can be drawn is that the Getty Gabbro is unlikely to be Neoproterozoic in age as suggested by Glen et al. (2013).


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Table SM1. Sample locations, depths and repository location.

Sample name Alternate name Drill hole Depth (m) Easting (MGA94) Northing (MGA94) Repository PANGBH7-01 RDB7001 BH7b 211.45–211.75

212.30–212.60 213.10–213.30

296754 6648552 UON

PANGBH7-10 RDB7010 Bh7b 337.80–339.30 296754 6648552 UON PANGBH5-04 RDB5004 BH5 325.80–326.16 307378 6634085 UON PANGBH6-01 RDB6001 BH6 190.80–191.70 312983 6636085 UON NBHT1-05 RDT1005 T-1 190.07–191.81 353715 6642183 UON NBHT1-06 RDT1006 T-1 231.65–232.37 353715 6642183 UON MYRTLE-06 RDMD006 MDH1 149.00–150.42 342616 6624822 UON GETTY5/6-1-02 RD5/6002 DH5/6-1 74.70–76.01 334816 6634883 UON GETTY6/7-1-01 RD6/7001 DH6/7-1 96.10–97.09 352915 6652083 UON MINOL21-02 RDL21002 L21RMD10-01 307.25–308.27

309.93–310.33 337230 6627789 UON

MINOL21-05 RDL21005 L21RMD10-01 276.53–276.93 279.33–279.73

337230 6627789 UON

MINOL30-04 RDL30004 L30RMD10-01 303.45–304.01 318.58–319

319153 6610652 UON

MINOL33-05 RDL33005 L33RMD10-01 240.30–241.21 322101 6608659 UON MINOL33-06 RDL33006 L33RMD10-01 284.95–285.53

288.12–288.60 322101 6608659 UON

RDT7 NSWPJG0053 331378 6636398 UON RDT1 NSWPJG0039, Mt Dijou 403042 6582676 UON

UON: University of Newcastle


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Table SM2. Summary of petrographic characteristics of key samples.

Sample/Rock type

Mineralogy Modal abundance

Grain size (mm)

Grain shape

PANGBH7-10 Kaersutitic gabbro

Kaersutite Plagioclase Titanaugite Opaques Apatite

30–60% 20–50% 5–10% 1–10% 1–2%

0.25–10 Up to 2.5 Up to 1.5 0.01–0.35 Up to 0.6

Subhedral poikilitic to squat euhedral Subhedral to euhedral tabular Fine microcrystalline aggregates to subhedral to euhedral and blocky Very fine granular to equant blocky subhedral skeletal grains Acicular to elongate prismatic

NBHT1-06 Alkaline gabbro

Plagioclase Titanaugite Opaques Biotite Apatite

50–60% 30–40% 5–10% 1–2% Minor

0.3–3.0 Up to 3.7 0.05–0.5 Up to 0.6

Elongate tabular euhedral to subhedral Subhedral poikilitic Euhedral to subhedral equant minor skeletal grains Equant to elongate platy Acicular microlites

MYRTLE-06 Alkaline gabbro

Plagioclase Titanaugite Opaques Kaersutite Biotite Apatite

50–65% 20–30% 3–10% 2–5% 1–5% 1–5%

Up to 5.0 0.1–3.0 0.08–1.2 Up to 2.5 Up to 0.7 Up to 0.5

Squat to elongate tabular euhedral to subhedral interlocking Medium equant to elongate euhedral through to fine microcrystalline aggregates Subhedral interstitial squat skeletal Anhedral to subhedral elongate Elongate to equant platy interstitial Equant to elongate euhedral prismatic

MINOL33-05 Calc-alkaline gabbro

Plagioclase Augite Opaques Biotite Apatite

50–60% 25–30% 7–15% 1–3% 1–2%

Unclear Up to 3.0 0.08–0.85 Up to .25 Up to 0.4

Intensely altered-tabular where preserved Euhedral to subhedral interstitial Subhedral interstitial skeletal/dendritic Platy to tabular, associated with opaques Microlite acicular through fine elongate and tabular/prismatic


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MINOL33-06 Volcanogenic sandstone

Quartz Calcite Muscovite Opaques Plagioclase Zircons

70–90% 5–15% ~ 3% 1–2% 0.5–1% Minor

0.06–1.0 Up to 0.5 Up to 0.4 Up to 0.1 Up to 0.5 Up to 0.1

Angular to subangular, moderately sorted. Interstitial patchy cement. Elongate lath-like defining tectonic fabric Angular generally equant grain fragments Blocky to tabular grain fragments Euhedral through rounded

MINOL21-02 Calc-alkaline dolerite

Plagioclase Augite Opaques Biotite Apatite

50–70% 25–40% 1–7% 1–2% 1–2%

0.5–3 0.7–2.5 0.1–2.5 0.1–0.3 Up to 0.5

Euhedral to subhedral. Euhedral through interstitial. Subhedral skeletal and elongate dendritic. Interstitial elongate and platy Acicular elongate

Table SM3. Geochemical and whole rock εNd samples sources.

Sample name (this study)

Drill hole Rock type Data type Analytical method Data source

PANGBH7-10 PANG BH7 Kaersutitic gabbro WR-GC εNd ICP-MS Sm–Nd IDA

This study

NBHT1-06 NBH T1 Alkaline gabbro WR-GC εNd ICP-MS Sm–Nd IDA

This study

NBHT2 NBH T2 Alkaline volcanic WR-GC ICP-MS Vickery (2008) MYRTLE-06 Pressugg MDH1 Alkaline gabbro WR-GC ICP-MS This study GETTY5/6-1-02 GETTY 5/6-1 Volcaniclastic sediment WR-GC NS Vickery (2008) GETTY6/7-1-01 GETTY 6/7-1 Alkaline gabbro to diorite WR-GC εNd ICP-MS This study Louth L1 EZ L1 Basalt WR-GC εNd NS Vickery (2008)


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Sm–Nd IDA This study(εNd) Louth L3 EZ L3 Basalt WR-GC NS Vickery (2008) Louth L4 EZ L4 Basalt WR-GC NS Vickery (2008) Mt Dijou FS Basalt εNd Sm–Nd IDA This study MINOL21-02 L21RMD10-02 Dolerite NWR-GC

εNd

ICP-MS ME-MS41 Sm–Nd IDA

GS2012-0157 This study(εNd)

MINOL33-05 L33RMD10-01 Dolerite to gabbro NWR-GC εNd

ICP-MS ME-MS41 Sm–Nd IDA

GS2012-0157 This study (εNd)

Macquarie Arc * Various WR-GC εNd

NS Crawford et al. (2007b)

Lachlan Orogen East * Various εNd Sm–Nd IDA Kemp et al. (2009) ACDWE008 ACDWE008 Basalt–andesite WR-GC

εNd NS Sm–Nd IDA

Vickery (2008) Whalen (2014) (εNd)

ACDWE009 ACDWE009 Basalt–andesite WR-GC εNd

NS Sm–Nd IDA


ACDWE010 ACDWE010 Basalt–andesite WR-GC εNd

NS Sm–Nd IDA


WR-GC, whole rock geochemistry; NWR-GC, near whole rocks geochemistry; ICP-M, laser ablation-inductively coupled plasma-mass spectrometry; Sm–Nd IDA, Samarium Neodymium isotope dilution analysis; NS, not specified; *, multiple field and diamond drill core samples; FS, field sample; ME-MS41, Aqua regia digestion; ME-MS61, HF–HNO3–HClO4 acid digestion, HCl leach.

Table SM4. Whole-rock geochemical data from this study.


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Elements Nb Nd P2O5 Pr Rb Sc SiO2 Sm Sr Ta Tb Th TiO2 Tm Total U V Y Yb Zr LOI-1000

Units ppm ppm % ppm ppm ppm % ppm ppm ppm ppm ppm % ppm % ppm ppm ppm ppm ppm % Detection 0.1 0.1 0.01 0.05 0.1 10 0.01 0.05 0.2 0.1 0.02 0.05 0.01 0.05 0.02 0.05 10 0.5 0.05 1 0.01

Sample numbers

MYRTLE-06 81.6 60.5 0.86 15.86 33.8 X 49.77 11.56 683.8 5.5 1.21 7.33 2.38 0.43 100.08 1.9 91 32.7 2.46 323 2.41 PANGB7-10 60.3 45.1 0.54 10.76 70.5 15 40.2 9.65 1115.6 4 1.08 3.93 4.65 0.31 99.5 1.02 304 26.7 1.84 230 5.97 NBHT1-06 40.9 29.6 0.44 7.36 42.2 16 42.44 6.22 755.3 2.8 0.78 3.46 3.56 0.32 99.99 0.81 341 21.7 1.79 161 3.78 GETTY6/7-01 78.8 39.2 0.77 10.32 59.5 X 43.17 7.66 433.9 5.1 0.9 7.29 2.31 0.34 100.02 1.68 119 26.1 1.85 212 6.83 Checks MYRTLE-06 81 63.4 0.85 16.34 34.5 X 49.89 11.84 690 5.5 1.23 7.66 2.33 0.55 99.98 1.97 93 33.4 2.55 326 2.31 Standards SY-4 13.6 54.6 0.13 14.15 53.7 X 49.89 12.79 1162.2 0.9 2.58 1.33 0.29 2.34 0.86 X 120.2 14.4 539 GSP-2 26.2 203.2 0.28 54.92 250.7 X 67.08 26.92 237.1 0.9 1.21 109.73 0.66 0.29 2.61 58 26.5 1.64 547 OREAS 45d 16.8 14 0.14 3.9 43.1 49 48.53 3.13 32 1.5 0.47 14.65 1.45 0.31 2.91 244 18.5 2.12 321


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Table SM5. Whole rock ɛNd data from this study.

Sample From Geology UOM GSNSW Melbourne University isotope dilution results

name

code Nd ppm approx

Sm ppm

Nd ppm

147Sm/144Nd 143Nd/144Nd eNd (now)

TDM1, Ga

Geol age T, Ga

eNd at age T

PANGB7-10 BH7 Pangaea, northwest

gabbro PG 09 40 13.48 63.21 0.1288 0.512682 1.0 0.84 0.243 3.1

MINOL21-05 L21 Minotaur, central

dolerite PG 06 15 10.10 51.87 0.1175 0.512552 –1.6 0.95 0.415 2.6

MINOL33-05 L33 Minotaur, southwest

gabbro PG 05 25 6.29 31.12 0.1220 0.512592 –0.8 0.93 0.415 3.1

PLJ0039 (RDT1)

Mt Dijou basalt PG39 66 12.30 73.06 0.1017 0.512519 –2.2 0.86 0.480 3.6

G07/982 from L1 hole, Vickery

basalt PG982 53 9.86 53.33 0.1116 0.512589 –0.8 0.84 0.420 3.7

NBHT1-06 NBH T1 hole, northeast

basalt PG1006 40 6.04 30.43 0.1198 0.512561 –1.4 0.96 0.260 1.1


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Table SM6. Summary of LA-ICP-MS U/Pb zircon results for PANGBH7-10.

Grain spot

207Pb/ 235U

± 2σ 206Pb/ 238U

± 2σ 238U /206Pb

± 2σ 207Pb/ 206Pb

± 2σ Age (Ma) 206Pb/238U

± Age (Ma) 207Pb/206Pb

± % Disc

U (ppm)

Th (ppm)

Pb (ppm)

U/Th

7010.01 3.937 0.089 0.2172 0.0061 4.604 0.129 0.1328 0.0020 1267 32 2135 27 41 2181 564 2205 4 7010.02 1.415 0.031 0.0659 0.0013 15.175 0.299 0.1530 0.0030 410.9 8 2387 33 83 3783 2075 5214 2 7010.03 0.605 0.015 0.0771 0.0018 12.970 0.303 0.0570 0.0011 479 11 483 45 1 687 174 67 5 7010-04 1.769 0.090 0.1705 0.0063 5.865 0.217 0.0750 0.0022 1013 35 1061 61 5 440 157 228 2 7010-05 4.160 0.150 0.2850 0.0067 3.509 0.082 0.1053 0.0030 1616 34 1722 53 6 1390 40 232 35 7010-06 0.403 0.016 0.03841 0.00073 26.035 0.495 0.0758 0.0028 243 4.5 1080 65 78 3404 5863 2176 1 7010-07 0.375 0.013 0.03844 0.00075 26.015 0.508 0.0703 0.0022 243.2 4.6 918 63 74 2986 3396 1667 1 7010-08 0.404 0.038 0.04001 0.00089 24.994 0.556 0.0732 0.0059 252.8 5.5 1010 110 75 2358 2761 1075 1 7010-09 3.680 0.260 0.1756 0.0043 5.695 0.139 0.1444 0.0070 1045 23 2202 68 53 1281 954 2591 1 7010-10 0.336 0.011 0.0365 0.00081 27.397 0.608 0.0657 0.0020 231.1 5 793 66 71 3868 10994 2743 0 7010-11 0.291 0.012 0.03675 0.00084 27.211 0.622 0.0575 0.0021 232.6 5.2 498 79 53 3170 3231 1583 1 7010-12 2.951 0.092 0.2102 0.0042 4.757 0.095 0.1010 0.0027 1229 22 1646 51 25 926 647 1357 1 7010-13 0.774 0.025 0.0920 0.0020 10.870 0.236 0.0606 0.0016 568 12 620 57 8 2112 1030 1628 2 7010-14 0.787 0.026 0.0942 0.0019 10.616 0.214 0.0603 0.0017 580 11 608 60 5 1252 609 1022 3 7010-15 4.540 0.170 0.3071 0.0074 3.256 0.078 0.1060 0.0029 1726 37 1731 49 0 649 102 506 10 7010-16 0.299 0.011 0.03901 0.00085 25.634 0.559 0.0550 0.0018 246.7 5.3 401 75 38 2863 2610 1676 1 7010-17 4.980 0.200 0.3030 0.0083 3.300 0.090 0.1183 0.0037 1705 41 1925 56 11 960 218 1407 4 7010-18 0.507 0.020 0.0529 0.0020 18.904 0.715 0.0701 0.0031 332 12 950 90 65 1172 527 231 2 7010-19 1.036 0.043 0.1036 0.0026 9.653 0.242 0.0719 0.0024 635 15 984 71 35 676 424 759 2 7010-20 0.305 0.013 0.03949 0.00096 25.323 0.616 0.0545 0.0022 249.6 6 376 91 34 1497 1003 632 1 7010-21 1.543 0.057 0.1457 0.0042 6.863 0.198 0.0775 0.0025 876 23 1127 64 22 1511 731 571 2 7010-22 2.850 0.094 0.2310 0.0048 4.329 0.090 0.0888 0.0023 1339 25 1401 50 4 1146 92 268 14 7010-23 0.303 0.016 0.0426 0.0013 23.474 0.716 0.0522 0.0026 269 7.9 280 110 4 831 389 259 2 7010-24 0.660 0.024 0.0847 0.0019 11.806 0.265 0.0574 0.0019 524 12 507 71 –3 1422 356 480 4 7010-25 0.577 0.024 0.0736 0.0018 13.587 0.332 0.0562 0.0022 458 11 464 88 1 704 211 124 3


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Grain spot

207Pb/ 235U

± 2σ 206Pb/ 238U

± 2σ 238U /206Pb

± 2σ 207Pb/ 206Pb

± 2σ Age (Ma) 206Pb/238U

± Age (Ma) 207Pb/206Pb

± % Disc

U (ppm)

Th (ppm)

Pb (ppm)

U/Th

7010-26 0.306 0.017 0.0430 0.0011 23.256 0.595 0.0516 0.0027 271.2 6.7 270 110 0 464 366 270 1 7010-27 0.581 0.021 0.0632 0.0015 15.823 0.376 0.0673 0.0020 395 9 838 64 53 1727 728 913 2 7010-28 0.704 0.027 0.0817 0.0023 12.240 0.345 0.0625 0.0022 506 14 689 77 27 1348 1347 700 1 7010-29 0.731 0.027 0.0912 0.0020 10.965 0.240 0.0590 0.0021 563 12 571 73 1 909 210 53 5 7010-30 1.591 0.050 0.1599 0.0032 6.254 0.125 0.0725 0.0020 956 18 997 54 4 954 535 971 2 7010-31 0.273 0.011 0.03856 0.0009 25.934 0.605 0.0518 0.0018 243.9 5.6 268 77 9 2545 1904 1112 1 7010-32 0.612 0.027 0.0770 0.0018 12.987 0.304 0.0574 0.0027 478 11 512 93 7 694 776 713 1 7010-33 0.605 0.026 0.0758 0.0020 13.193 0.348 0.0581 0.0024 471 12 518 91 9 929 1480 1770 1 7010-34 0.547 0.035 0.0634 0.0014 15.773 0.348 0.0623 0.0029 396.2 8.5 577 63 31 880 606 695 1 7010-35 2.810 0.093 0.2302 0.0050 4.344 0.094 0.0895 0.0024 1335 26 1413 52 6 1213 83 348 15 7010-36 1.801 0.059 0.0797 0.0021 12.547 0.331 0.1649 0.0048 494 12 2502 49 80 1955 3300 2924 1 7010-37 5.060 0.170 0.2615 0.0055 3.824 0.080 0.1410 0.0039 1497 28 2244 46 33 575 277 1165 2


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Figure SM1. (a) TL and CL images of concordant Permo-Triassic aged zircons recovered from

PANGBH7-10 displaying the characteristic grain morphology of the alkaline group. Note the similarities in grain morphology and zoning between zircons from PANGBH7-10 and the two volcaniclastic sample PANGBH5-04 and PANGBH6-01. (b) CL images modified after Grime et al. (2009) displaying the characteristic zoning of zircons recovered from mafic rocks which is broadly similar to the zoning observed in zircons recovered from the alkaline group. All scale bars are 100 µm.

a.

b.


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Figure SM2. TL and CL images of zircons recovered from PANGBH5-04 and PANGBH6-01 displaying the characteristic grain morphology of the alkaline

group. Note the similarities in grain morphology and zoning to zircons recovered from PANGBH7-10 suggesting these grains were potentially derived from a similar gabbroic host rock to PANGBH7-10. (a) TL and CL images of concordant Permo-Triassic aged zircons recovered from PANGBH6-01. (b) TL and CL images of concordant Permo-Triassic aged zircons recovered from PANGBH5-04. All scale bars are 100 mm.

a. b.


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Figure SM3. Probability density plots of temperatures obtained from Permo-Triassic aged zircons recovered from PANGBH5-04 and PANGBH6-01 (a) are broadly similar to those from mafic rocks (b) but show a wider temperature range and peaks not observed in the mafic datasets from Fu et al. (2008). When compared with the patterns of volcanic (c) and mafic rocks, the broader pattern potentially represents a mafic pattern superimposed over a volcanic one (Fu et al., 2008).


14

Figure SM4. Wetherill-type concordia diagrams and probability density plots of concordant data for

additional samples from the Permo-Triassic alkaline group. (a) Sample NBHT1-05 underlying NBHT1-06. Both samples return the same emplacement/MDA. NBHT1-05 features a provenance signal similar to that of detrital samples from Louth and the NLO including a 415 ± 15 Ma, which is in error of the Early Devonian age of the calcalkaline Louth Volcanics. (b) Sample GETTY5/6-1-02. This was found within an alkaline breccia sequence but only returned discordant Permo-Triassic ages. Provenance signals are similar to samples from Louth and the NLO and include Devonian to Carboniferous ages suggesting incorporation of detrital components from the Lower Devonian Louth Volcanics and the Winduck/Mulga Downs Groups. (c) A large quantity of zircons were recovered for PANGBH7-01 but they were so fine (~ 20–30 mm) that analytical options were limited and returned mostly discordant results. This sample is located at the same approximate depth as PANGBH6-01 and appear to represent the same sequence of volcanogenic and volcaniclastic sedimentary rocks. The results from this samples are so limited that it is possible the youngest component was not analysed, and this age is considered unlikely to represent this unit’s true MDA. (d) Discordia regression of apatite data from the Getty Gabbro. Analysis of apatite grains separated from the Getty Gabbro did not return concordant ages but a discordia regression is suggestive of a Permian age. The precision is so poor that the only conclusion that can be drawn is that the Getty Gabbro is unlikely to be Neoproterozoic in age as suggested by Glen et al. (2013).

100 300 500 700 900 1100 1300 1500 1700 1900

Rel

ativ

e pr

obab

ility

Age (Ma)

MDA261±8.9n = 1

414

490

566

536

798

921

1019

1240

1597

0.0

0.1

0.2

0.3

0 1 2 3 4 5

207Pb/235U

206 P

b/23

8 U200

600

1000

1400

1800

data-point error ellipses are 2s

Sample - NBHT1-05Tuffaceous siltstonen = 30 of 32

MDA261±8.9n = 1

100 300 500 700 900 1100 1300 1500 1700

Rel

ativ

e pr

obab

ility

Age (Ma)

n = 52 of 64

InferredMDA241

269438

506

604

811

1067

9771176

1722340

383

0.00

0.04

0.08

0.12

0.16

0.20

0.0 0.4 0.8 1.2 1.6 2.0 2.4207Pb/235U

206 P

b/23

8 U

100

300

500

700

900

1100

data-point error ellipses are 2s

Sample - GETTY5/6-1-02Volcanogenic sandstoneto conglomeraten = 48 of 64

InferredMDA241±8.1

300 500 700 900 1100 1300 1500 1700 1900

Rel

ativ

e pr

obab

ility

Age (Ma)

n = 12 of 13

Youngestconcordantgrain431±15

484

520

1060

1179

10191357

16211923

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

0.4 0.8 1.2 1.6 2.0 2.4207Pb/235U

206 P

b/23

8 U

400

600

800

1000

1200data-point error ellipses are 2s

Sample - PANGBH7-01Sandy siltstonen = 9 of 13

Youngestconcordantgrain431±15

a.b.

c.

d.

Documents

Age and tectonic significance of the Louth Volcanics