LA-ICP-MS zircon age of volcanic rock of Shiling Formation in Tunxi area, south Anhui, and redetermination of its epoch

The Tunxi area in south Anhui Province is located in the eastern segment of the Jiangnan Neoproterozoic Orogen and possesses some volcanic rocks of Shiling Formation like rhyolite and tuff. Based on the K-Ar age 115~139Ma by 1:50000 regional geological survey, previous studies believed that these volcanic rocks of Shiling Formation from Tunxi area were formed during Late Jurassic to Early Cretaceous. Owing to the change of the Jurassic-Cretaceous boundary from 135Ma to 145Ma(revised by International Commission on Stratigraphy), the Shiling Formation has thus changed its formation epoch from Late Jurassic-Early Cretaceous to Early Cretaceous. The authors obtained LA-ICP-MS zircon U-Pb weighted average age of 154.7±2.5Ma for the rhyolite from Youxi Village, east Tunxi(D047), south Anhui Province, implying that the volcanic rocks of Shiling Formation was formed in Late Jurassic(older than 145Ma), rather then in Eearly Cretaceous. This precise datum is valuable for a better understanding of tectonomagmatic evolution of south Anhui and even southeast China.