Magnesium Isotopic Evidence for Ancient Subducted Oceanic Crust in LOMU‐Like Potassium‐Rich Volcanic Rocks
Magnesium Isotopic Evidence for Ancient Subducted Oceanic Crust in LOMU‐Like Potassium‐Rich Volcanic Rocks
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DOI：
10.1002/2017jb014560
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发表时间：
2017-10
期刊：
影响因子：
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通讯作者：
Yang Sun;F. Teng;Jifeng Ying;B. Su;Yan Hu;Q. Fan;Xin-hua Zhou
中科院分区：
文献类型：
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作者：
Yang Sun;F. Teng;Jifeng Ying;B. Su;Yan Hu;Q. Fan;Xin-hua Zhou
为了评价俯冲洋壳在富钾岩浆成因中的作用，我们报道了中国东北一套新生代火山岩的高精度Mg同位素数据。这些岩石的Mg同位素组成总体上比正常地幔轻，并显示出相当大的Mg同位素变化，δ 26 Mg介于− 0.61至− 0.23之间。δ 26 Mg与TiO2的协变表明，轻Mg同位素组成来源于源区碳酸盐榴辉岩形式的再循环洋壳。δ 26 Mg与（Gd/Yb）N比值和Sr-Pb同位素的相关性进一步表明了这些岩石的多组分和多阶段成因。因此，镁同位素可作为幔源岩浆源区再循环洋壳的新示踪剂。
To evaluate the role of subducted oceanic crust in the genesis of potassium‐rich magmas, we report high‐precision Mg isotopic data for a set of Cenozoic volcanic rocks from Northeast China. These rocks overall are lighter in Mg isotopic composition than the normal mantle and display considerable Mg isotopic variations, with δ26Mg ranging from −0.61 to −0.23. The covariation of δ26Mg with TiO2 in these rocks suggests that their light Mg isotopic compositions were derived from recycled oceanic crust in the form of carbonated eclogite in the source region. The strong correlations between δ26Mg and (Gd/Yb)N ratio as well as Sr‐Pb isotopes further indicate a multicomponent and multistage origin of these rocks. Magnesium isotopes may thus be used as a novel tracer of recycled oceanic crust in the source region of mantle‐derived magmas.