Discovery of the Early Proterozoic Basement in the Middle-Lower Reaches of Yangtze River and Its Significance

The middle-lower reaches of the Yangtze River are a famous copper-ironmetallogenic belt, but many vital basic geologic problems about lithogenesis andmineralization are hard to be solved, since the metamorphic basement has not beendiscovered. Although Dongling Group metamorphic rock series outcrops in Huaining,Anhui Province, and Huangxu System metamorphic rock series outcrops in NingzhenMountain in Jiangsu Province, they are generally considered to be of the Sinian, dueto their low metamorphism and the lack of convincible isotopic age data. Dongling