The High-pressure Metamorphosed Pelitic and Mafic Rocks in E. Shandong: Ages and Tectonic Nature

The Paleoproterozoic Jiao-Liao-Ji Belt (JLJB) is a NNE-SSW trending continental belt lying in the Eastern Block of the North China Craton, with its southern segment extending across Bohai Sea into the Jiaobei massif. Little work has been done in the southern segment of the belt, and thus the timing for metamorphism and tectonic nature of the JLJB are still controversial, with models ranging from those invoking continent-arc-continent collision to those advocating rifting closure. The presence of the high-pressure pelitic and mafic rocks of the Jiaobei massif (Eastern Shandong) located in the southern segment is crucial to these controversial isues. The aim of this study is to resolve these issues through an integrated study including field study followed by geochronological and metamorphic investigations on the high-pressure pelitic and mafic rocks in the Jiaobei massif. By combining the geochronological and metamorphic data, the results of this study suggest that the JLJB represented a Paleoproterozoic rift-and-collision belt along which the Longgang and Nangrim blocks amalgamated to form the Eastern Block at 1.93?1.90 Ga.