Pervasive Neoarchean melting of subducted sediments generating sanukitoid and associated magmatism in the North China Craton, with implications for the operation of plate tectonics

<br> Measurements of U-Pb isotopes were carried out by an inductively coupled plasma-mass spectrometer (ICP-MS) coupled with a NewWave 193UC excimer laser ablation system at the China University of Geosciences, Beijing (CUGB). Detailed procedures were described by Zhang et al. (2019). Data off-line analysis was conducted following Ludwig (2003), Andersen (2002), and Liu et al. (2010). <em>In situ </em>zircon Hf isotopes were collected using a <em>Neptune plus</em> multicollector (MC)-ICP-MS system equipped with a NewWave 193UC excimer laser ablation system at CUGB. Instrumental conditions and analytical procedures were described by Wu et al. (2006). During these analyses, the 176Hf/177Hf ratio of standard zircon <em>Plešovice</em> was 0.282481 ± 22 (2σ), which is consistent within error with the recommended value in Sláma et al. (2008). <br> Major element oxides were determined with an X-ray fluorescence spectrometer at the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS). Analytical accuracies are better than 1%. Trace elements were determined by a high-resolution ICP-MS (Element-XR) at CUGB. Based on the USGS standards GPS-2 and BHVO-2, the analytical accuracy of most trace elements is better than 5%. Samples for the whole-rock Sr-Nd isotope analysis were performed using a <em>Neptune Plus</em> MC-ICP-MS at CUGB, following the analytical procedures described by those of Li et al. (2022). Measured 87Sr/86Sr and 143Nd/144Nd ratios were normalized to 86Sr/88Sr = 0.1194 and 146Nd/144Nd = 0.7219, respectively, in exponential law. The measured average 87Sr/86Sr ratio for the SRM 987 standard and 143Nd/144Nd ratio for the Alfa Nd standard during the analytical process were 0.710246 ± 14 (2SD, n=15) and 0.512420 ± 14 (2SD, n=15), respectively. Measured values for the rock standard BHVO-2 were 87Sr/86Sr = 0.703473 ± 15 and 143Nd/144Nd = 0.512990 ± 9, respectively, both of which are consistent with the recommended ratios (http://georem.mpch-mainz.gwdg.de). Zinc (Zn) isotopes were measured with a <em>Neptune Plus</em> MC-ICP-MS at CGUB, following the detailed analytical methodology described by Liu et al. (2016). The instrumental mass fractionation effects were calibrated using the sample-standard bracketing method. About 2 V signals for 66Zn were collected for a 200 ppb Zn solution using high-sensitivity (X) cones in low-resolution mode. All samples were analyzed over three blocks for 40 cycles with ~8 s integration. The measured Zn isotope ratios are presented in δ-notation form in per mil relative to JMC 3-0749L: δ66, 68Zn (‰) = ((δ66, 68Zn/δ64Zn) sample / (δ66, 68Zn/δ64Zn) JMC 3-0749L-1) *1000 Measured values for the GSP-2 and BHVO-2 Zn standards were δ66Zn GSP-2 = 1.02 ± 0.01 ‰ (n = 9) and δ66Zn BHVO-2 = 0.31 ± 0.03 ‰ (n = 12), respectively, both of which are consistent with previously reported values within uncertainty (Liu et al., 2016; Wang et al., 2017b; Sossi et al., 2018; Chen et al., 2021).

U-Pb同位素测试由电感耦合等离子体质谱仪（inductively coupled plasma-mass spectrometer, ICP-MS）搭配NewWave 193UC准分子激光剥蚀系统，在中国地质大学（北京）（China University of Geosciences, Beijing, CUGB）完成，详细实验流程参见Zhang等（2019）的研究。离线数据分析方法遵循Ludwig（2003）、Andersen（2002）及Liu等（2010）的研究方案。原位（in situ）锆石Hf同位素测试采用配备NewWave 193UC准分子激光剥蚀系统的Neptune plus多接收电感耦合等离子体质谱仪（multicollector-ICP-MS, MC-ICP-MS），于CUGB完成，仪器参数与分析流程参见Wu等（2006）的研究。本次分析中，标准锆石Plešovice的¹⁷⁶Hf/¹⁷⁷Hf比值为0.282481 ± 22（2σ），该结果与Sláma等（2008）推荐的标准值在误差范围内一致。
主量元素氧化物测试在中国科学院地质与地球物理研究所（Institute of Geology and Geophysics, Chinese Academy of Sciences, IGGCAS）的X射线荧光光谱仪上完成，分析精度优于1%。微量元素测试采用CUGB的高分辨ICP-MS（Element-XR）完成，以美国地质调查局（USGS）标准物质GPS-2和BHVO-2为质控基准，多数微量元素的分析精度优于5%。
全岩Sr-Nd同位素分析样品在CUGB采用Neptune Plus MC-ICP-MS完成，分析流程遵循Li等（2022）的实验方案。测试得到的⁸⁷Sr/⁸⁶Sr和¹⁴³Nd/¹⁴⁴Nd比值分别以⁸⁶Sr/⁸⁸Sr = 0.1194和¹⁴⁶Nd/¹⁴⁴Nd = 0.7219为基准进行指数法校正。分析过程中，标准物质SRM 987的平均⁸⁷Sr/⁸⁶Sr比值为0.710246 ± 14（2SD, n=15），标准物质Alfa Nd的平均¹⁴³Nd/¹⁴⁴Nd比值为0.512420 ± 14（2SD, n=15）。岩石标准物质BHVO-2的测试结果为⁸⁷Sr/⁸⁶Sr = 0.703473 ± 15、¹⁴³Nd/¹⁴⁴Nd = 0.512990 ± 9，二者均与官方公开的推荐比值（http://georem.mpch-mainz.gwdg.de）一致。
锌（Zn）同位素测试在CUGB采用Neptune Plus MC-ICP-MS完成，分析方法细节参见Liu等（2016）的研究。采用样品-标准穿插法校正仪器的质量分馏效应。以低分辨模式搭配高灵敏度（X）锥对200 ppb的Zn溶液采集⁶⁶Zn信号，信号强度约为2 V。所有样品分3个批次分析，每批次40个循环，积分时间约8 s。锌同位素比值以δ符号表示，相对于JMC 3-0749L标准，计算公式为：δ⁶⁶,⁶⁸Zn (‰) = [((⁶⁶,⁶⁸Zn/⁶⁴Zn)样品 / (⁶⁶,⁶⁸Zn/⁶⁴Zn)JMC 3-0749L) - 1] × 1000。标准物质GSP-2和BHVO-2的测试结果分别为δ⁶⁶Zn_GSP-2 = 1.02 ± 0.01 ‰（n=9）、δ⁶⁶Zn_BHVO-2 = 0.31 ± 0.03 ‰（n=12），二者均与已有文献报道的结果在误差范围内一致（Liu et al., 2016; Wang et al., 2017b; Sossi et al., 2018; Chen et al., 2021）。