Abstract: The Weng'an Dome is located in the transitional region between the Hubei-Chongqing-Hunan-Guizhou dome group in near N-S direction and the Qianzhong Uplift in the E-W direction. Our research suggests that the Wengan Dome is essentially a superimposed tectonic dome. Caledonian, Indosinian and Yanshanian unconformities are developed and well retained in the Wengan Dome and its surrounding area. Unconformity characteristics corresponding to key tectonic events and age constraint are important factors in reconstructing regional geology and tectonics. Our results can be summarized as follows: (1) The Wengan Dome experienced three major deformations during the Paleozoic and Mesozoic. It is a superimposed tectonic dome with cratonic basement. The S2/AnS2, T2/AnT2 and J2/AnJ2 unconformities are distinguishable within the Weng'an Dome and its surrounding area, and they correspond to the Caledonian, Indosinian and Yanshanian tectonic movements in the Yangtze Block, respectively. And (2) The ages of unconformities, constrained by using detrital zircon U-Pb method, demonstrate that the Caledonian, Indosinian and Yanshanian tectonic events occurred during 426415, 246233 and 168150 Ma, respectively. Through structural and chronological analyses of unconformities, we also explored the tectonic evolution of the dome, which shall contribute to the in-depth study of the dome structure.

Key words: Yangtze Block, Weng'an Dome, unconformity, detrital zircon analysis