U‐Pb Zircon Age, Geochemical, and Sr‐Nd‐Pb Isotopic Constraints on the Age and Origin of Mafic Dykes from Eastern Shandong Province, Eastern China
U‐Pb Zircon Age, Geochemical, and Sr‐Nd‐Pb Isotopic Constraints on the Age and Origin of Mafic Dykes from Eastern Shandong Province, Eastern China
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DOI：
10.1111/1755-6724.12109
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发表时间：
2013-08
期刊：
影响因子：
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通讯作者：
Liu Shen;Hu Rui-zhong;Feng Caixia;G. Shan;Feng Guangying;Lai Shao-cong;Qi Youqiang;I. Coulson;Yang Yuhong;Yan Chao-gui;Tang Liang
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文献类型：
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作者：
Liu Shen;Hu Rui-zhong;Feng Caixia;G. Shan;Feng Guangying;Lai Shao-cong;Qi Youqiang;I. Coulson;Yang Yuhong;Yan Chao-gui;Tang Liang
本文报道了胶东中国东部镁铁质岩墙的锆石U-Pb年龄、地球化学和锶-钕-铅同位素资料。利用激光烧蚀电感耦合等离子体质谱(LA-ICPMS)对两个镁铁质岩墙样品进行了锆石U-Pb值分析，获得了121.9 Ma±0.47 Ma到122.9 Ma±0.6 Ma的一致年龄。镁铁质岩脉具有高(87Sr/86Sr)i=0.7087~0.7089，低ε(T)值为−16.9~−17.8,206Pb204Pb17.15~17.17,207Pb204Pb15.45~15.47,208Pb204Pb37.59~37.68的特征。目前的研究结果表明，镁铁质岩墙来自古代岩石圈地幔的部分熔融，并与下地壳沉没榴辉岩的熔体发生不同程度的杂化。镁铁质岩脉可能是在岩浆上升过程中通过随后的微不足道的晶体分馏和非常轻微的地壳混染而产生的。结合前人的研究，这些发现提供了新的证据，证明山东东部中国以东的强烈岩石圈减薄发生在∼120 Ma，并且这种减薄是由于下部岩石圈(地幔和下地壳)的剥离造成的。
U‐Pb zircon age, geochemical, and Sr‐Nd‐Pb isotopic data of mafic dykes from eastern Shandong Province, eastern China is reported herein. Laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) U‐Pb zircon analyses of two samples from the investigated mafic dykes yield consistent ages ranging from 121.9 Ma ± 0.47 Ma to 122.9 Ma ± 0.61 Ma. The mafic dykes are characterized by high (87Sr/86Sr)i ranging from 0.7087 to 0.7089, low εNd(t) values ranging from −16.9 to −17.8, 206Pb/204Pb = 17.15 to 17.17, 207Pb/204Pb = 15.45 to 15.47, and 208Pb/204Pb = 37.59 to 37.68. Results from the current study suggest that the mafic dykes are derived from partial melting of ancient lithospheric mantle that was variably hybridized by melts derived from foundered lower crustal eclogite. The mafic dykes may have been generated through subsequent insignificant crystal fractionation and very minor crustal contamination during magma ascent. Combined with previous studies, the current findings provide new evidence that the intense lithospheric thinning beneath the eastern Shandong Province of eastern China occurred at ∼120 Ma, and that this condition was caused by the removal of the lower lithosphere (mantle and lower crust).