扬子板块东北缘中元古代的大地构造划分

Middle Proterozoic geotectonics in the northeast margin of the Yangtze plate

扬子板块东北缘存在四条主要的中元古代变质带,自南向北依次为江南变质带、沿江变质带、云台—张八岭变质带和连云港—泗阳变质带。它们分别为中元古代的古弧后盆地、火山岛弧、裂谷及弧前盆地,扬子板块东北缘中元古代为活动大陆边缘构造体系。苏(北)胶(南)变质造山带应解体,其中一部分属扬子大陆边缘体系。

There are four main Middle Proterozoic metamorphic belts in the northeast margin of the Yangtze plate,namely, Jiangnan metamorphic belt, metamorphic belt along the Yangtze River, Yuntai- Zhangbaling metamorphic belt and Lianyungang-Siyang metamorphic belt from south to north. The metamorphic belts belong to the Middle Proterozoic paleo-back-arc basin, volcanic arc, rift valley and forearc basin, respectively. During the Middle Proterozoic era, the northeast Yangtze plate was an active continental margin. The reconstruction of tectonic system of the northeast Yangtze plate shows that the Presinian Su-Jiao （north Jiangsu-south Shandong） metamorphic orogenic belt should be disintegrated into north sector of the Yangtze plate and south sector of North China plate and part of the Su-Jiao metamorphic orogenic belt should belong to the Yangtze continental margin system though no reliable evidence for the recognition of trench belt in the northeast margin of the Yangtze plate during the Middle Proterozoic can be found. A number of isotopic ages show that main Yangtze orogenic events in North China, determined as Indosinian orogenic movement, are only a result of reactivation of the Su-Jiao orogenic belt.