Basement components of the Xiangshan-Yuhuashan area, South China: Defining the boundary between the Yangtze and Cathaysia blocks

U-Pb ages of detrital zircons show that the protoliths of the xenoliths are mainly composed of Neoproterozoic, Neoarchean and Paleoproterozoic detritus, similar to the components of the Wuyi terrane in the eastern Cathaysia Block. In contrast, the protoliths of the exposed metasedimentary rocks consist mainly of Neoproterozoic detritus with minor Neoarchean and Paleoproterozoic fragments, similar to those in the southern Yangtze Block. Both geochemistry and zircon U-Pb-Hf isotope compositions suggest that the deep basement metamorphic rocks in the XSYHS area belong to the Wuyi terrane, whereas the surface metamorphic rocks are derived from the southern Yangtze Block. Therefore, the real boundary between the Yangtze and Cathaysia blocks lies north of the study area. The exposed Yangtze-related metamorphic rocks were overthrust southward from the southern Yangtze Block, and onto the Cathaysia basement, during the Indosinian to Yanshanian Orogeny.