Neoproterozoic tectonic evolution of the Xuefeng orogenic zone in Hunan

The present paper deals, on the basis of abundant lithogeochemical and geochronologic data, with the reconstruction of the Neoproterozoic tectonic evolution in the Xuefeng orogenic zone and its southeastern margin. During 880-820 Ma, the Xuefeng orogenic zone was initiated in the stage of island-arc magmatism, and the Chengbu region on its southeastern margin appeared as a forearc basin. During 820-810 Ma, the Xuefeng orogenic zone experienced the stage of arc-continent collision, and the Chengbu region displays the transition from a forearc basin to an island arc. During 810-800 Ma, the Xuefeng orogenic zone went into the post-collision stage, and a new island arc came into being in the Chengbu region. Till 800-630 Ma, both the Xuefeng orogenic zone and its southeastern margin were developed into the rift basin without exception. The Neoproterozoic tectonic evolution outlined above suggests the island arc accretion on the southeastern margin of the Yangtze landmass, and overlapping of the Xuefengian and Nanhuan deposits upon the Huanan residual oceanic basin.