U-Pb-Hf zircon data from Bruce Rise and Naturaliste Plateau

These dataset files (2 tables) are supplementary material to: Halpin, J.A., Daczko, N.R., Direen, N.G., Mulder, J.A., Murphy, R.C., Ishihara, T., 2020. Provenance of rifted continental crust at the nexus of East Gondwana breakup. Lithos 354-355. https://www.sciencedirect.com/science/article/pii/S0024493719305237?via%3Dihub https://doi.org/10.1016/j.lithos.2019.105363 They include: Supplementary Table 1. Zircon U-Pb datasets Supplementary Table 2. Zircon Lu-Hf datasetsSample details from Halpin et al. (2020):Ishihara et al. (1996) made initial reports of the dredge sites from which our analyses have been made. Dredging at four sites on the eastern margin of the Bruce Rise was undertaken during cruise TH-94 of the R/V Hakurei-Maru during the austral summer of 1994/5, along with other geophysical data acquisition reported in Ishihara et al. (1996). Of the four sites dredged, sites D1502, D1503 and D1504 all recorded hauls of basement rocks, including crystalline basement fragments. These dredge sites and hauls are summarised in Table 1. The recovered dredge samples have variable shapes, but the samples analysed here (two granites from D1502; Fig. 3) contain sharp and unweathered faces consistent with dredging from in situ basement. The interpretation of composite seismic profiles TH94/21 and GA-229/19 from the eastern flank of the Bruce Rise (Fig. 1b) shows a folded and faulted syn-rift sequence that thickens towards the south and is separated from flat-lying post-rift sediments by a prominent erosional unconformity (Stagg et al., 2006). The outermost ridge, flanked by the Vincennes Fracture Zone, is interpreted to comprise exposed crystalline basement, and we interpret the granitic samples studied here to represent parts of this basement complex.Sample D1502-A is a medium to coarse-grained (~2–4 mm) red granite, whereas sample D1502-B is a fine to medium-grained (~1–1.5 mm) cream-grey granite (Fig. 3a). Both samples comprise quartz, plagioclase, alkali feldspars (including microcline), biotite and accessory magnetite and zircon. Sample D1502-B additionally contains minor biotite-amphibole-rich schlieren. Biotite is variably orientated suggesting weak magmatic foliation. The low-strain character of the samples is supported by very limited undulose extinction of some grains, minor development of sub grains in quartz, and preserved igneous microstructures that include subhedral feldspar grains presenting some crystal faces (red lines, Fig. 3b), quartz-feldspar interstitial textures (blue ‘i’, Fig. 3b), low dihedral angles (double blue arrow heads, Fig. 3b), elongate mineral films along grain boundaries that are inferred to have pseudomorphed former melt, and growth twinning in plagioclase. Minor low-temperature alteration of feldspar and biotite to sericite ± chlorite is observed in sample D1502-A. High resolution whole thin section photomicrographs are available at https:// imagematrix.science.mq.edu.au/.Details of analytical methods from Halpin et al. (2020):Initial sample preparation including zircon separation and mounting was performed at Curtin University. Zircon grains were imaged via cathodoluminescence (CL) on a FEI Quanta 600 SEM at the Central Science Laboratory, University of Tasmania, to reveal internal structure in order to optimise and contextualise U-Pb analyses. U-Pb zircon analyses were performed on an Agilent 7500cs quadrupole ICPMS with a 193nm Coherent Ar-F gas laser and the Resonetics S155 ablation cell at the Discipline of Earth Sciences, University of Tasmania. Each analysis was pre-ablated with 5 laser pulses to remove the surface contamination then the blank gas was analysed for 30 s followed by 30 s of zircon ablation at 5 Hz and ~2 J/cm2 using a spot size of 29 μm. Isotopes measured include 49Ti, 56Fe, 91Zr, 178Hf, 202Hg, 204Pb, 206Pb, 207Pb, 208Pb, 232Th and 238U. The down hole fractionation, instrument drift and mass bias correction factors for Pb/U and Pb/Th ratios on zircons were calculated using the primary standard (91500, Wiedenbeck et al., 1995) and secondary standards (TEMORA 1, Black et al., 2003; Plešovice, Sláma et al., 2008) analysed at the beginning of the session and every 15–20 unknowns using the same spot size and conditions as used on the samples to provide an independent control to assess accuracy and precision. The correction factor for the 207Pb/206Pb ratio was calculated using 17 analyses of the international glass standard NIST610 analysed throughout the analytical session and corrected using the recommended values (Baker et al., 2004). All data reduction calculations and error propagations were done within Microsoft Excel® via macros designed at the University of Tasmania (see Halpin et al., 2014; Sack et al., 2011). No common Pb corrections were applied. However, time-resolved isotopic ratios for each analysis were scrutinised on concordia diagrams to investigate the presence of common Pb and/or ancient Pb-loss and/or mixing of age zones, and analyses (or parts of analyses) were excluded from the dataset where a combination of these trends was detected. Uncertainties quoted in Supplementary Tables and in figures are the internal measured uncertainty only (i.e., those from random based sources of error, e.g., counting statistics). External sources of uncertainty (i.e., from systematic sources of uncertainty, e.g., decay constant uncertainty, uncertainty in the age of the primary zircon standard) calculated after Horstwood et al. (2016) and Thompson et al. (2018) are quoted in parentheses for the standard data below (see also Supplementary Table 1). 206Pb/238U ages for the secondary zircon standards Plešovice and TEMORA 1 over the course of this study (at 95% confidence) are 333.6 ± 2.7 (4.3) Ma (n = 7, MSWD = 1.3) and 415.1 ± 3.2 (5.3) Ma (n = 6, MSWD = 0.4), compared to the published TIMS zircon ages of 337.13 ± 0.37 Ma (Sláma et al., 2008) and 416.8 ± 1.1 Ma (Black et al., 2003), respectively. Although Plešovice is slightly outside 2σ of the internal uncertainties, it is well within the published values when considering the external uncertainties. The primary zircon standard 91500 yields a 207Pb/206Pb weighted mean age of 1065.3 ± 8.8 (10.5) Ma (n = 27, MSWD = 0.71) within error of the recommended value of 1065.4 ± 0.3 Ma (Wiedenbeck et al., 1995). Tera-Wasserburg diagrams and age calculations were made using Isoplot v4.11 (Ludwig, 2003). Uncertainties for individual analyses as quoted in text and as error bars on U\\Pb plots have been calculated to the two-sigma level. Weighted mean and intercept ages are reported at 95% confidence limits.Hf isotope analyses were performed in situ on a subset of the same grains analysed for U-Pb using a Photon Machines Excimer 193 nm Ar-F laser ablation micro-probe attached to a Nu Plasma multi- collector (MC)-ICPMS system at Macquarie University GeoAnalytical (MQGA)(see Griffin et al., 2004 for a detailed methodology). A gas blank was analysed for 30 s followed by up to 120 s of ablation at a beam diameter of 40–50 μm, 5 Hz and ~7.5 J/cm2. Zircon CL images were used to ensure that Hf isotope analyses overlapped the same do- main analysed for U-Pb. The Mud Tank and Temora-2 zircon standards were used as a reference standard for Hf analysis; our weighted average 176Hf/177Hf values for these standards are 0.282526 ± 41 (n = 17, MSWD = 1.6) and 0.282678 ± 10 (n = 7, MSWD = 2.1), respectively, within error of the published values of 0.282523 ± 43 (Mud Tank; Griffin et al., 2006) and 0.282680 ± 24 (Temora-2; Woodhead et al., 2004). Uncertainties quoted are the internal measured uncertainty and do not include any propagation of error from the reference standard. The initial 176Hf/177Hf value (Hfi) in zircon is calculated using the measured 176Lu/177Hf, 176Hf/177Hf and apparent 207Pb/206Pb age and the 176Lu decay constant of Scherer et al. (2001) of 1.865 x 10-11. Model age calculations (TDM) are based on a depleted-mantle source with Hfi = 0.279718 and 176Lu/177Hf = 0.0384. This provides a value of 176Hf/177Hf (0.28325) similar to that of average mid-ocean ridge basalt over 4.56 Ga. The calculated TDM ages use the measured 176Lu/177Hf of the zircon and give a minimum age for the source material of the magma from which the zircon crystallised. Two-stage model ages (TDM2) are calculated assuming that the parental magma was derived from the average continental crust (176Lu/177Hf = 0.015), which in turn was originally derived from the depleted mantle.

本数据集文件（共2张数据表）为以下论文的补充材料：Halpin, J.A., Daczko, N.R., Direen, N.G., Mulder, J.A., Murphy, R.C., Ishihara, T., 2020. 东冈瓦纳裂解交汇处裂谷型大陆地壳的成因。《岩石学》（Lithos）354-355卷。https://www.sciencedirect.com/science/article/pii/S0024493719305237?via%3Dihub https://doi.org/10.1016/j.lithos.2019.105363

本数据集包含：
补充表1 锆石U-Pb数据集（Zircon U-Pb datasets）
补充表2 锆石Lu-Hf数据集（Zircon Lu-Hf datasets）

Halpin等人（2020）中的样品细节如下：
Ishihara等人（1996）首次报道了本研究开展分析所用的拖网采样站位。1994/1995年南半球夏季，“白岭丸”号（R/V Hakurei-Maru）TH-94航次在布鲁斯海隆（Bruce Rise）东缘的4个站位开展了拖网采样，同时采集了其他地球物理数据，相关内容详见Ishihara等人（1996）的报道。4个拖网站位中，D1502、D1503和D1504均采获了基底岩石，包括结晶基底碎块。本研究的拖网站位及采样情况详见表1。采获的拖网样品形态各异，但本研究分析的样品（采自D1502站位的2件花岗岩样品；图3）具有尖锐且未风化的表面，符合原位基底拖网采样的特征。

对布鲁斯海隆东翼的复合地震剖面TH94/21和GA-229/19的解译结果显示，一套经历褶皱和断裂的同裂谷层序向南逐渐增厚，且被显著的侵蚀不整合面与平缓产出的后裂谷沉积物分隔（Stagg等人，2006）。文森斯断裂带（Vincennes Fracture Zone）两侧的最外海岭被解译为裸露的结晶基底，本研究分析的花岗岩样品即属于该基底杂岩的一部分。

D1502-A为中粗粒（约2~4 mm）红色花岗岩，而D1502-B为细中粒（约1~1.5 mm）米灰色花岗岩（图3a）。两件样品均由石英、斜长石、碱性长石（包括微斜长石）、黑云母以及副矿物磁铁矿和锆石组成。D1502-B还含有少量富黑云母-角闪石的析离体条带。黑云母的排列方向存在变化，指示存在微弱的岩浆叶理。

样品的低应变特征得到以下证据支持：部分矿物颗粒的波状消光极弱，石英中仅发育少量亚颗粒，且保留了完整的火成显微结构，包括：具部分晶面的半自形长石颗粒（图3b红色线条）、石英-长石间隙结构（图3b蓝色标记“i”）、低二面角（图3b蓝色双箭头）、沿粒界分布的细长矿物膜（被认为是原熔体假像）以及斜长石的生长双晶。D1502-A样品中可见长石和黑云母发生轻微的低温蚀变，转变为绢云母±绿泥石。高清全薄片显微照片可通过以下链接获取：https://imagematrix.science.mq.edu.au/。

Halpin等人（2020）中的分析方法细节如下：
初始样品制备（包括锆石分选与制靶）在科廷大学完成。在塔斯马尼亚大学中央科学实验室，使用FEI Quanta 600型扫描电镜（Scanning Electron Microscope, SEM）的阴极发光（Cathodoluminescence, CL）系统对锆石颗粒进行成像，以揭示其内部结构，从而优化U-Pb分析点位并明确分析背景。

锆石U-Pb同位素分析在塔斯马尼亚大学地球科学系完成，使用配备193 nm Coherent Ar-F准分子激光器与Resonetics S155剥蚀池的Agilent 7500cs四极杆电感耦合等离子体质谱仪（Inductively Coupled Plasma Mass Spectrometry, ICPMS）。每个分析点位先以5个激光脉冲进行预剥蚀以去除表面污染，随后采集30 s的空白气体本底，接着以29 μm的束斑直径、5 Hz频率、约2 J/cm²的能量密度对锆石进行30 s的剥蚀分析。测试的同位素包括49Ti、56Fe、91Zr、178Hf、202Hg、204Pb、206Pb、207Pb、208Pb、232Th和238U。

锆石Pb/U与Pb/Th比值的井下分馏、仪器漂移及质量分馏校正因子，通过分析标准样品计算得到：分析批次开始时以及每15~20个未知样品时，使用与样品分析相同的束斑直径与实验条件，对一级标准物质（91500，Wiedenbeck等人，1995）以及二级标准物质（TEMORA 1，Black等人，2003；Plešovice，Sláma等人，2008）进行分析，以此作为独立质控以评估分析的准确度与精密度。207Pb/206Pb比值的校正因子通过分析全批次分析过程中的17次国际玻璃标准物质NIST610得到，并采用推荐值进行校正（Baker等人，2004）。

所有数据处理计算与误差传递均通过塔斯马尼亚大学开发的宏程序在Microsoft Excel®中完成（详见Halpin等人，2014；Sack等人，2011）。本次分析未进行普通Pb校正。但通过谐和图对每个分析点位的时间分辨同位素比值进行了核查，以判断是否存在普通Pb、古老Pb丢失或年龄区间混合的情况；若检测到上述多种趋势的组合，则将该分析（或其部分数据）从数据集中剔除。

补充表与图中给出的不确定度仅为内部测量不确定度（即来源于随机误差的不确定度，例如计数统计误差）。下文标准数据的不确定度（另见补充表1）采用括号标注，其外部不确定度（即来源于系统误差的不确定度，例如衰变常数不确定度、一级锆石标准物质的年龄不确定度）按照Horstwood等人（2016）与Thompson等人（2018）的方法计算得到。

本研究中二级锆石标准物质Plešovice与TEMORA 1的206Pb/238U年龄（95%置信度）分别为333.6±2.7(4.3) Ma（n=7，MSWD=1.3）与415.1±3.2(5.3) Ma（n=6，MSWD=0.4）；而已发表的热电离质谱（Thermal Ionization Mass Spectrometry, TIMS）锆石年龄分别为337.13±0.37 Ma（Sláma等人，2008）与416.8±1.1 Ma（Black等人，2003）。尽管Plešovice的内部不确定度2σ范围与已发表值略有偏差，但考虑外部不确定度后，其结果完全落在已发表值的范围内。

一级锆石标准物质91500的207Pb/206Pb加权平均年龄为1065.3±8.8(10.5) Ma（n=27，MSWD=0.71），与推荐值1065.4±0.3 Ma（Wiedenbeck等人，1995）在误差范围内一致。Tera-Wasserburg图解与年龄计算采用Isoplot v4.11软件完成（Ludwig，2003）。正文与U-Pb图解误差棒中给出的单个分析点位的不确定度均为2σ水平。加权平均年龄与交点年龄均以95%置信限报告。

锆石铪同位素原位分析在麦考瑞大学地球分析实验室（Macquarie University GeoAnalytical, MQGA）开展，使用连接Nu Plasma多接收电感耦合等离子体质谱仪（Multi-collector Inductively Coupled Plasma Mass Spectrometry, MC-ICPMS）的Photon Machines Excimer 193 nm Ar-F准分子激光剥蚀微探针完成，分析对象为部分与U-Pb分析相同的锆石颗粒（详细方法见Griffin等人，2004）。先采集30 s的气体本底，随后以40~50 μm的束斑直径、5 Hz频率、约7.5 J/cm²的能量密度进行最长120 s的剥蚀分析。采用锆石阴极发光图像确保铪同位素分析点位与U-Pb分析点位位于同一区域。

本次分析采用Mud Tank与Temora-2锆石标准物质作为铪同位素分析的参考标准；本研究得到的这两个标准物质的176Hf/177Hf加权平均比值分别为0.282526±41（n=17，MSWD=1.6）与0.282678±10（n=7，MSWD=2.1），与已发表值0.282523±43（Mud Tank；Griffin等人，2006）及0.282680±24（Temora-2；Woodhead等人，2004）在误差范围内一致。报告的不确定度仅为内部测量不确定度，不包含参考标准物质带来的误差传递。

锆石的初始176Hf/177Hf比值（Hfi）通过实测的176Lu/177Hf比值、176Hf/177Hf比值、表观207Pb/206Pb年龄以及Scherer等人（2001）给出的176Lu衰变常数（1.865×10^-11）计算得到。模式年龄（TDM）以亏损地幔为源区，其Hfi=0.279718，176Lu/177Hf=0.0384；该源区的176Hf/177Hf比值为0.28325，与45.6亿年以来的平均洋中脊玄武岩（Mid-Ocean Ridge Basalt, MORB）比值相近。计算得到的TDM年龄采用锆石实测的176Lu/177Hf比值，代表锆石结晶时岩浆源区的最小形成年龄。两阶段模式年龄（TDM2）的计算假设母岩浆来源于平均大陆地壳（176Lu/177Hf=0.015），而该大陆地壳最初起源于亏损地幔。