The Arabian Nubian Shield (ANS) is one of the largest juvenile continental crust formed after the Archean. To determine the timing and understand the mechanism of its early crustal growth, we conducted geochronological and geochemical studies on granitoids from northern Ethiopia. A plagiogranite, dated at 929.7 ± 2.2 Ma, represents one of the early granitoids from the ANS. It shows low K2O, TiO2, and REE contents, flat REE pattern and absence of Eu anomaly. Moreover, it exhibits (87Sr/86Sr)i, ƐNd(t) and ƐHf(t) values of 0.70341, +5.0 and +8.4, respectively. Its zircon δ18O value is 4.8‰, lower than the mantle value. These characteristics suggest that it was derived from partial melting of altered oceanic crust. The oxygen fugacity obtained from zircon trace elements is ΔFMQ+1.3, consistent with a subduction setting.

中文翻译：

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阿拉伯努比亚地盾中幼年地壳生长过程中的长弧增生：来自埃塞俄比亚北部花岗岩的见解


阿拉伯努比亚地盾 （ANS） 是太古宙之后形成的最大的幼年大陆地壳之一。为了确定时间并了解其早期地壳生长的机制，我们对埃塞俄比亚北部的花岗岩进行了地质年代学和地球化学研究。斜长花岗岩的年代为 929.7 ± 2.2 马，是 ANS 的早期花岗岩之一。它显示 K2O、TiO2 和 REE 含量低，REE 模式平坦，没有 Eu 异常。此外，它的 （87Sr/86Sr）i、ƐNd（t） 和 ƐHf（t） 值分别为 0.70341、+5.0 和 +8.4。其锆石δ18O值为4.8‰，低于地幔值。这些特征表明，它是由蚀变的海洋地壳部分融化产生的。从锆石痕量元素获得的氧逸度为 ΔFMQ+1.3，与俯冲设置一致。