Timing and Provenance Transition of the Neoproterozoic Wuling Unconformity and Xihuangshan Unconformity of the Yangtze Block: Responses to Peripheral Orogenic Events

Middle Neoproterozoic sedimentary strata are widely distributed on the periphery of Yangtze Block. In western Jiangnan Orogen, they divided into Lengjiaxi and Banxi groups by “Wuling unconformity,” Group is further Madiyi Formation Wuqiangxi “Xihuangshan unconformity.” However, timing tectonic significance Wuling Xihuangshan unconformities remain unclear, which hampers our understanding Precambrian evolution Zircon U–Pb dating Lu–Hf isotopic analysis were performed rocks above below two unconformity boundaries in Orogen. These data used to trace provenance provide new insights basin unconformities. Combined with previous studies, bracketed have formed between ~830 813 Ma, sediments remained unchanged. The detrital zircons from upper parts lower show primary peak ages 800–1000 1.0–1.30 Ga, 1.40–1.90 2.30–2.60 mainly derived southwestern margin Block, Cathaysia Block occurred part Group, indicating that merged Orogen earlier than formation time (~830–813 Ma) collisional eastern (~820–800 Ma). Thus, collision blocks may undergone a scissor-like closure process west east. was at ~800–779 Ma. field contact relationships changed an angular disconformity then conformity, north south, controlled movement north. unconformity. zircon age peaks 755–1000 1.90–2.10 2.35–2.70 detritus northern This coeval ~800–780 Ma orogeny northwestern margins likely response induces transition provenance.