海南蓬莱地幔橄榄岩全岩Re-Os同位素组成

海南蓬莱地幔橄榄岩全岩和橄榄石的Re-Os同位素组成限定出该区域TRD年龄为0.8-1.6Ga。该数据在中国地质大学（北京）科学研究院同位素地球化学实验室完成，采用的是同位素稀释剂法，详细的分 析流程见Xu et al.（2020）。流程简述如下：（1）大概0.6-1g的200目样品粉末和HSE混合稀释剂（包括99Ru、105Pd、185Re、190Os、191Ir和194Pt）一起加入到含有反王水的Carius管中，240℃加热72 h。（2）利用CCl4将Os从反王水中萃取出来，之后反萃取到HBr中，并通过微蒸馏进一步提纯。（3）Os提取出来后，用阳离子交换树脂（AG50 W-X8，100-200目）将Ir-Ru-Pt-Pd-Re从残留溶液中分离纯化，其具体流程如表2-1所示。为了去除Zr-Mo-Hf-W对过柱后收集的HSE溶液产生影响，需将溶液进行BPHA氯仿溶剂萃取。此外，一些样品的Cd含量较高，会对Pd的测试结果产生影响，需要进一步用AG50 W-X8（100-200目）树脂（2 ml）进行淋洗，淋洗介质为0.2 mol/L的HCl，淋洗体积为2-5 ml（Fisher-Gödde et al., 2010）。
Os同位素是以OsO3-的形式通过负离子模式的热电离质谱仪（N-TIMS）分析测定的（详细测试方法见Liu and Pearson， 2014），采用法拉第杯（Faraday Cup）或二次电子倍增器（SEM）进行接收（根据样品的信号强度选择）。Os样品点在Pt带上，利用电流烘干后，均匀地涂上一层Ba(OH)2助发剂。Os原始数据的校正包括：（1）校正氧同位素干扰，其中氧同位素17O/16O = 0.0003749，18O/16O = 0.0020439；（2）扣除稀释剂对样品187Os/188Os的贡献；（3）使用192Os/188Os = 3.08271进行仪器质量分馏校正。187Os/188Os的测试精度和整个实验流程数据的可靠性和准确性，可以通过测试参考物质溶液UMD（马里兰大学；UMD = 0.113794 ± 0.000038，2σ，n = 5）、DROSS（Durham Romil Os标样；DROSS = 0.160922 ± 0.000026，2σ，n = 7）和岩石标样UB-N（蛇纹石化二辉橄榄岩；UB-N = 0.12742 ± 0.00009，2σ，n = 3；Os含量为3.36 ppb；）、MUH-1（方辉橄榄岩；MUH-1 = 0.12506 ± 0.00019，2σ，n = 1；Os含量为5.72 ppb）来监控，本论文的测试结果在误差范围内与文献中报道的值一致（Luguet et al., 2008; van de Löcht et al., 2018）。
HSE的含量是通过Thermo Fisher Scientific公司生产的Element 2/XR型 HR-ICP MS完成测试的。分析方法的精度是通过参考标样UB-N（Ir = 3.35 ppb；Ru = 8.19 ppb；Pt = 7.13 ppb；Pd = 5.78 ppb；Re = 0.22 ppb）和MUH-1（Ir = 3.22 ppb；Ru = 9.04 ppb；Pt = 9.28 ppb；Pd = 12.32 ppb；Re = 0.20 ppb）的值来监测，与文献中报道值和GEOREM推荐值误差范围内一致（Ishikawa et al., 2014; van de Löcht et al., 2018）。整个实验流程的平均本底为（n = 3）：Os = 1.3 pg；Ir = 3.4 pg；Ru = 4.7 pg；Pt = 3.0 pg；Pd = 2.0 pg；Re = 0.87 pg，对于所有样品来说可以忽略不计（＜1%）。

Whole-rock and olivine Re-Os isotopic compositions of mantle peridotites from Penglai, Hainan Province constrain the TRD model age of this region to be 0.8–1.6 Ga. This dataset was generated at the Isotope Geochemistry Laboratory, School of Science, China University of Geosciences (Beijing), using the isotope dilution method. Detailed analytical procedures are described in Xu et al. (2020).

The detailed analytical procedures are summarized as follows:
(1) Approximately 0.6–1 g of 200-mesh sample powder was added to a Carius tube containing reversed aqua regia, along with a mixed highly siderophile element (HSE) spike (including 99Ru, 105Pd, 185Re, 190Os, 191Ir, and 194Pt), and heated at 240 ℃ for 72 h.
(2) Os was extracted from the reversed aqua regia using CCl4, then back-extracted into HBr, and further purified via micro-distillation.
(3) After Os extraction, Ir, Ru, Pt, Pd, and Re were separated and purified from the residual solution using cation exchange resin (AG50 W-X8, 100–200 mesh), with specific procedures presented in Table 2-1. To eliminate the interference of Zr, Mo, Hf, and W on the collected HSE solution after column chromatography, the solution was subjected to BPHA-chloroform solvent extraction. Additionally, some samples have high Cd contents, which would interfere with Pd measurement, requiring further elution with AG50 W-X8 (100–200 mesh) resin (2 mL), using 0.2 mol/L HCl as the elution medium and an elution volume of 2–5 mL (Fisher-Gödde et al., 2010).

Os isotopes were analyzed and measured via negative-ion mode thermal ionization mass spectrometry (N-TIMS) in the form of OsO3- (detailed analytical methods are provided in Liu and Pearson, 2014), with signals detected using a Faraday Cup or secondary electron multiplier (SEM), selected based on sample signal intensity. Os samples were loaded onto Pt filaments, dried using electric current, and uniformly coated with a Ba(OH)2 activator. Corrections for raw Os data include:
(1) Correction for oxygen isotope interference, with 17O/16O = 0.0003749 and 18O/16O = 0.0020439;
(2) Subtraction of the spike contribution to the sample 187Os/188Os ratio;
(3) Instrumental mass fractionation correction using 192Os/188Os = 3.08271.
The measurement precision of 187Os/188Os and the reliability and accuracy of data from the entire experimental procedure can be monitored by analyzing reference material solutions UMD (University of Maryland; UMD = 0.113794 ± 0.000038, 2σ, n = 5), DROSS (Durham Romil Os standard; DROSS = 0.160922 ± 0.000026, 2σ, n = 7), and rock standards UB-N (serpentinized lherzolite; UB-N = 0.12742 ± 0.00009, 2σ, n = 3; Os content = 3.36 ppb), MUH-1 (harzburgite; MUH-1 = 0.12506 ± 0.00019, 2σ, n = 1; Os content = 5.72 ppb). The analytical results of this study are consistent with values reported in the literature within error margins (Luguet et al., 2008; van de Löcht et al., 2018).

The concentrations of HSEs were measured using an Element 2/XR high-resolution inductively coupled plasma mass spectrometer (HR-ICP-MS) manufactured by Thermo Fisher Scientific. The precision of the analytical method was monitored using reference standards UB-N (Ir = 3.35 ppb; Ru = 8.19 ppb; Pt = 7.13 ppb; Pd = 5.78 ppb; Re = 0.22 ppb) and MUH-1 (Ir = 3.22 ppb; Ru = 9.04 ppb; Pt = 9.28 ppb; Pd = 12.32 ppb; Re = 0.20 ppb), with results consistent with reported literature values and GEOREM recommended values within error margins (Ishikawa et al., 2014; van de Löcht et al., 2018).

The average background of the entire experimental procedure (n = 3) is as follows: Os = 1.3 pg; Ir = 3.4 pg; Ru = 4.7 pg; Pt = 3.0 pg; Pd = 2.0 pg; Re = 0.87 pg, which is negligible (<1%) for all samples.

搜集汇总

背景与挑战

背景概述

该数据集提供了海南蓬莱地区地幔橄榄岩全岩的Re-Os同位素组成数据，限定该区域TRD年龄为0.8-1.6Ga，揭示了地幔演化的时间特征。数据在中国地质大学（北京）采用同位素稀释法和负离子模式热电离质谱仪等先进技术分析，并通过参考标样监控确保了高精度和可靠性，适用于地球化学和地质年代学研究。