Provenance and Crustal Evolution of the Northern Yangtze Block Revealed by Detrital Zircons from Neoproterozoic-Early Paleozoic Sedimentary Rocks in the Yangtze Gorges Area, South China

Detrital zircon U-Pb ages of six sedimentary rocks in the northern Yangtze Block reveal three major age groups of 740-890 Ma, 1.9-2.1 Ga, and 2.4-2.55 Ga and two minor groups of 2.6-2.7 and 2.9-3.1 Ga. Although Lu-Hf isotope analysis suggest both juvenile crustal growth and reworking of old crust for all the age populations, juvenile input occurred mainly in the Archean and Neoproterozoic time, whereas Paleoproterozoic is a period dominated by recycling of preexisting crust. The predominant Neoproterozoic detritus is mainly derived from coeval igneous rocks distributed along the western and northwestern margin of the Yangtze Block. However, most of the pre-Neoproterozoic sediments cannot be matched with exposed basement rocks within the Yangtze Block. The similar age patterns of the sedimentary rocks in this study imply only a slight variation in the source regions from the Neoproterozoic to Silurian.