Discovery of Eoarchean Gneisses in Northern Dabie Belt
Eoarchean rocks are of great significance for understanding the formation and evolution of the earliest continental crust due to their scarcity.In this study,it reports zircon U-Pb ages of a newly recognized tonalitic gneiss and plagioclase-amphibolitic gneiss assemblage in the northern Dabie belt,which is named as the"Muzidian gneiss complex".The zircon dating results show that the ages of the plagioclase-amphibolitic schist and tonalitic gneiss in the Muzidian gneiss complex are(3 653±43)Ma and(3 701±29)Ma,respectively,which are the oldest rocks known in the Yangtze craton,indicating ancient basement rocks may exist beneath the craton.A comparative study with the basement rocks of the Kongling complex reveals that both the lithology and age of the Muzidian gneiss complex are distinct from those of the Kongling complex,indicating that they may represent independent microcontinental nucleus of the Yangtze craton.
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