Abstract Reworking or growth of the Hadean (>4.0 Ga) continental crust provides important hints in understanding the early evolution history of Earth. In this study, a comprehensive program of zircon U Pb dating and Hf isotope analyses, as well as whole-rock major and trace element analyses, has been carried out on the Muzidian granitic gneisses from the northern Dabie orogen. The Muzidian gneisses are tonalite or granodiorite in composition, and have geochemical features resembling those typical of the tonalite-trondhjemite-granodiorite (TTG) suites. Zircon U Pb dates range from ~2.5–2.4 Ga in the magmatic cores and from ~2.1–2.0 Ga in the metamorphic rims. Both the zircon cores and the rims have highly negative ɛHf(t) values of −25.2 to −19.9 and − 31.0 to −28.1, respectively, corresponding to Tcrust of 4.25 Ga to 3.98 Ga, thereby, indicating that the protoliths of the orthogneisses in the northern Dabie orogen were formed by reworking of Hadean continental crust. This provides strong evidence for the presence of Hadean continental crust in the northern Yangtze block. These remnants of Hadean rocks resided in the continental crust of the Yangtze block for more than about 1700 Ma before being reworked. Compared to the ancient crustal components in the Kongling area of the Yangtze block, the Muzidian area along the northern margin of the Yangtze block seems to be more prospective for further occurrences of the Hadean zircon and/or rocks.

中文翻译：

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大别造山带中冥河大陆地壳的改造：来自木子甸花岗片麻岩的证据

摘要 Hadean (>4.0 Ga) 大陆地壳的改造或生长为理解地球早期演化历史提供了重要线索。本研究对大别造山带北部的木子店花岗片麻岩进行了锆石U Pb定年、Hf同位素分析以及全岩主微量元素分析的综合方案。木子店片麻岩的成分为闪长岩或花岗闪长岩，具有类似于典型的闪长岩-长闪长岩-花岗闪长岩（TTG）组的地球化学特征。锆石 U Pb 日期范围为岩浆核中的~2.5-2.4 Ga，变质边缘中的~2.1-2.0 Ga。锆石核和边缘都具有非常负的 ɛHf(t) 值，分别为 -25.2 至 -19.9 和 -31.0 至 -28.1，对应于 4.25 Ga 至 3.98 Ga 的 Tcrust，因此，表明大别造山带北部正片麻岩的原岩是由哈德斯大陆地壳改造形成的。这为扬子地块北部存在冥河大陆地壳提供了强有力的证据。这些冥河岩石的残余物在被重新加工之前在扬子地块的大陆地壳中存在了大约 1700 Ma。与扬子地块空岭地区的古地壳成分相比，扬子地块北缘木子店地区似乎更有可能进一步发现冥河锆石和/或岩石。这些冥河岩石的残余物在被重新加工之前在扬子地块的大陆地壳中存在了大约 1700 Ma。与扬子地块空岭地区的古地壳成分相比，扬子地块北缘木子店地区似乎更有可能进一步发现冥界锆石和/或岩石。这些冥河岩石的残余物在被重新加工之前在扬子地块的大陆地壳中存在了大约 1700 Ma。与扬子地块空岭地区的古地壳成分相比，扬子地块北缘木子店地区似乎更有可能进一步发现冥界锆石和/或岩石。