The Paleozoic tectonic framework and paleo–plate configuration of the northern margin of Gondwana remain controversial. The South Qiangtang terrane is located along the northern margin of Gondwana and records key pro...The Paleozoic tectonic framework and paleo–plate configuration of the northern margin of Gondwana remain controversial. The South Qiangtang terrane is located along the northern margin of Gondwana and records key processes in the formation and evolution of this supercontinent. Here, we present new field, petrological, zircon U-Pb geochronological, and Lu-Hf isotopic data for granitic rocks of the Gemuri pluton, all of which provide new insights into the evolution of the northern margin of Gondwana. Zircon U-Pb dating of the Gemuri pluton yielded three concordant ages of 488.5 ± 2.1, 479.9 ± 8.9, and 438.5 ± 3.5 Ma. Combining these ages with the results of previous research indicates that the South Qiangtang terrane records two magmatic episodes at 502–471 and 453–439 Ma. These two episodes are associated with enriched zircon Hf isotopic compositions(εHf(t) =-10.1 to-3.9 and-16.6 to-6.5, respectively), suggesting the granites were formed by the partial melting of Paleoproterozoic–Mesoproterozoic metasedimentary rocks(Two–stage Hf model ages(TCDM) = 2094–1704 and 2466–1827 Ma, respectively). Combining these data with the presence of linearly distributed, contemporaneous Paleozoic igneous rocks along the northern margin of Gondwana, we suggest that all of these rocks were formed in an active continental margin setting. This manifests that the two magmatic episodes within the Gemuri area were associated with southward subduction in the Proto-(Paleo-) Tethys Ocean.展开更多
目的建立基于糖诱导相分离技术结合超高效液相色谱-高分辨质谱法(ultra performance liquid chromatography-high resolution mass spectrometry,UPLC-HRMS)测定牛奶中高氯酸盐含量的分析方法。方法样品制备采用乙腈为提取溶剂,木糖为...目的建立基于糖诱导相分离技术结合超高效液相色谱-高分辨质谱法(ultra performance liquid chromatography-high resolution mass spectrometry,UPLC-HRMS)测定牛奶中高氯酸盐含量的分析方法。方法样品制备采用乙腈为提取溶剂,木糖为相分离诱导剂。分析物经Poroshell 120(50 mm×2.1 mm,1.9μm)色谱柱分离,以甲醇-1%乙酸水溶液为流动相进行梯度洗脱。采用电喷雾负离子模式与单一离子监测(targeted single ion monitoring,tSIM)扫描模式,结合同位素内标法进行定量。结果在0.1~20.0μg/L的范围内,高氯酸盐线性关系良好(r^(2)=0.9988)。方法检出限(limits of detection,LODs)和定量限(limits of quantification,LOQs)分别为0.1μg/L和0.3μg/L;3个加标水平下,回收率为88.7%~116.8%,相对标准偏差为2.3%~8.1%。在30份牛奶样品的检测分析中,高氯酸盐的检出率达100%。结论该方法操作简便,对样品净化效果良好,具有低成本、高灵敏度的优点,适用于牛奶中高氯酸盐检测。展开更多
基金supported by the Second Tibetan Plateau Scientific Expedition and Research(STEP)(Grant Nos.2019QZKK0703 and 2019QZKK0702)National Science Foundation of China(Grant Nos.91755103 and 41872240)+1 种基金Ministry of Science and Technology of China(Grant No.2016YFC0600304)the Chinese Geological Survey Project(Grant Nos.DD20190060,DD20190370 and DD20190057)。
文摘The Paleozoic tectonic framework and paleo–plate configuration of the northern margin of Gondwana remain controversial. The South Qiangtang terrane is located along the northern margin of Gondwana and records key processes in the formation and evolution of this supercontinent. Here, we present new field, petrological, zircon U-Pb geochronological, and Lu-Hf isotopic data for granitic rocks of the Gemuri pluton, all of which provide new insights into the evolution of the northern margin of Gondwana. Zircon U-Pb dating of the Gemuri pluton yielded three concordant ages of 488.5 ± 2.1, 479.9 ± 8.9, and 438.5 ± 3.5 Ma. Combining these ages with the results of previous research indicates that the South Qiangtang terrane records two magmatic episodes at 502–471 and 453–439 Ma. These two episodes are associated with enriched zircon Hf isotopic compositions(εHf(t) =-10.1 to-3.9 and-16.6 to-6.5, respectively), suggesting the granites were formed by the partial melting of Paleoproterozoic–Mesoproterozoic metasedimentary rocks(Two–stage Hf model ages(TCDM) = 2094–1704 and 2466–1827 Ma, respectively). Combining these data with the presence of linearly distributed, contemporaneous Paleozoic igneous rocks along the northern margin of Gondwana, we suggest that all of these rocks were formed in an active continental margin setting. This manifests that the two magmatic episodes within the Gemuri area were associated with southward subduction in the Proto-(Paleo-) Tethys Ocean.
文摘目的建立基于糖诱导相分离技术结合超高效液相色谱-高分辨质谱法(ultra performance liquid chromatography-high resolution mass spectrometry,UPLC-HRMS)测定牛奶中高氯酸盐含量的分析方法。方法样品制备采用乙腈为提取溶剂,木糖为相分离诱导剂。分析物经Poroshell 120(50 mm×2.1 mm,1.9μm)色谱柱分离,以甲醇-1%乙酸水溶液为流动相进行梯度洗脱。采用电喷雾负离子模式与单一离子监测(targeted single ion monitoring,tSIM)扫描模式,结合同位素内标法进行定量。结果在0.1~20.0μg/L的范围内,高氯酸盐线性关系良好(r^(2)=0.9988)。方法检出限(limits of detection,LODs)和定量限(limits of quantification,LOQs)分别为0.1μg/L和0.3μg/L;3个加标水平下,回收率为88.7%~116.8%,相对标准偏差为2.3%~8.1%。在30份牛奶样品的检测分析中,高氯酸盐的检出率达100%。结论该方法操作简便,对样品净化效果良好,具有低成本、高灵敏度的优点,适用于牛奶中高氯酸盐检测。
