Abstract The Abu Dabbab rare-metal granite in the Eastern Desert of Egypt is a highly-evolved alkali-feldspar granite with transitional magmatic-hydrothermal features. Extreme geochemical fractionation and the associated significant Ta Sn resource make the Abu Dabbab intrusion an important feature in the metallogenic evolution of the Arabian-Nubian Shield. U Pb dating by laser ablation sector field (SF)-ICPMS analysis of igneous monazite yields a Concordia age of 644.7 ± 2.3 Ma, identical within uncertainty to a lower intercept Tera-Wasserburg isochron age of 644.2 ± 2.3 Ma obtained from hydrothermal cassiterite. Both ages place tight constraints on the timing of magmatic-hydrothermal processes in the Abu Dabbab granite which represents the oldest highly-evolved granite recognized so far in the Pan-African Arabian-Nubian Shield. Thus, the new ages also date the start of a period of late-orogenic metalliferous granite magmatism, when the basement of the Eastern Desert underwent a geodynamic transition from a compressive subduction-collision regime towards orogenic collapse in the late Cryogenian.

中文翻译：

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埃及 Abu Dabbab 稀有金属花岗岩的独居石和锡石 U Pb 定年：阿拉伯-努比亚地盾中的晚低温纪含金属花岗岩岩浆作用

摘要 埃及东部沙漠的阿布达巴稀有金属花岗岩是一种高度演化的碱长石花岗岩，具有岩浆-热液过渡特征。极端的地球化学分馏和相关的重要 Ta Sn 资源使 Abu Dabbab 侵入体成为阿拉伯-努比亚地盾成矿演化的重要特征。通过激光烧蚀扇形场 (SF)-ICPMS 对火成岩独居石进行 U Pb 测年，得出 Concordia 年龄为 644.7 ± 2.3 Ma，与从热液锡石获得的较低截距 Tera-Wasserburg 等时线年龄 644.2 ± 2.3 Ma 在不确定性内相同。这两个时代都严格限制了阿布达巴花岗岩中岩浆-热液过程的时间，这是迄今为止泛非阿拉伯-努比亚地盾中公认的最古老的高度演化的花岗岩。因此，