Here we report the first set of thallium (Tl) isotope data in alkaline rocks from the North China Craton to constrain the nature of recycled materials in the metasomatized subcontinental lithospheric mantle. Samples from the Hekanzi and Saima alkaline complexes display Tl isotope compositions (ε²⁰⁵Tl) identical to the present-day upper mantle and continental crust, suggesting that neither the recycled low-temperature altered oceanic crust nor the pelagic sediments were involved in their sources. The volcanic rocks from the Liaodong-Jinan region, whose source was previously proposed to contain recycled low-temperature altered oceanic crust, also display modern mantle-like Tl isotope composition, suggesting a significant Tl-loss in the recycled oceanic crust during the subduction due to the dehydration process. Our Tl isotope data provide complementary constraints to the Sr-Nd-Hf-O isotopes on the nature of metasomatic agent in the subcontinental lithospheric mantle.

中文翻译：

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使用铊同位素追踪次大陆岩石圈地幔中的回收地壳材料

在这里，我们报告了华北克拉通碱性岩石中的第一组铊（Tl）同位素数据，以限制交代次大陆岩石圈地幔中再生材料的性质。来自 Hekanzi 和 Saima 碱性配合物的样品显示 Tl 同位素组成 (ε ²⁰⁵Tl) 与今天的上地幔和大陆地壳相同，这表明循环的低温蚀变洋壳和远洋沉积物均不参与其来源。辽东-济南地区的火山岩，其来源之前被认为包含循环的低温蚀变洋壳，也显示出现代地幔状Tl同位素组成，表明在俯冲过程中循环洋壳的Tl损失显着到脱水过程。我们的 Tl 同位素数据为 Sr-Nd-Hf-O 同位素对次大陆岩石圈地幔中交代剂的性质提供了补充约束。