SHRIMP zircon U-Pb dating of the early Late Cretaceous felsic volcanic rock in southern Jiangxi-northern Guangdong area and its geological significance

The early Late Cretaceous red sedimentary rocks with basalt intercalations at the bottom are widely developed in southeastern China, and the asymmetric bimodal volcanic rocks of felsic volcanic rocks comprising mainly rhyolite and some basalt intercalations at the bottom are extensively spread in Changtang, Renju and Xunwu basin in south Jiangxi-north Guangdong area. The zircon SHRIMP U-Pb dating results of felsic volcanic rocks show that rhyolite ages in Changtang and Renju are 96.8Ma±1.4Ma and 95.5Ma±1.3Ma respectively, and the porphyroclastic lava age in Xunwu is 96.7Ma±1.1Ma. The felsic volcanic rocks belong to early Late Cretaceous. The volcanic rocks are all felsic volcanic rocks in Banshi basin, and the zircon SHRIMP U-Pb age of middle tuff and upper rhyolite are 142.5Ma±1.3Ma and 131.4Ma±1.3Ma respectively, suggesting that they were formed during early Early Cretaceous period. So the volcanic rocks in Changtang, Renju and Xunwu basin cannot be correlated with the volcanic rocks in Banshi basin. Geological age studies of the felsic volcanic rocks in Changtang, Renju and Xunwu basin have proved that asymmetric bimodal volcanic rocks composed mainly of rhyolite with some basalt on west and east sides of Yuyao-Lishui-Zhenghe- Dapu fault occurred in different geological periods, formed earlier in the east and later in the west. These results have important significance for the study of magmatic activity and tectonic evolution during Mesozoic in southeastern China.