Detrital zircon U-Pb dating of the Late Cretaceous aeolian sandstones from the Tangbian Formation in the Yiyang area of Jiangxi Province and its provenance significance

The Tangbian Formation of the Late Cretaceous Guifeng Group in the Xinjiang Basin of northeastern Jiangxi Province is characterized by large-scale cross-bedded sandstones. They are generally products of a desert depositional environment under arid climate. The sandstone samples are purple red, fine-to medium-grained feldspar quartz sandstones. Sand particles are mainly composed of quartz, feldspar, mica and rock fragments, which are subangular to subrounded and well sorted. In order to analyze the source rocks of the Tangbian Formation, LA-ICP-MS zircon U-Pb analysis was performed. The zircon grains are mostly larger than 100μm. The results show that the Th/U ratios range from 0.1 to 2.1, and most of the zircons have a clear internal shock band structure, indicating that most of them were magmatic zircons. The mean age of ²⁰⁶Pb/²³⁸U is 141.4±1.2Ma. The age of zircon U-Pb ages are mainly concentrated in five zones of 137~170Ma, 431~506Ma, 798~1172Ma, 1268~2493Ma, 2501~3488Ma, corresponding to the major magmatic events in Southeast China, namely Yanshanian, Caledonian, Jinning, and Lvliang movements, with the Yanshanian volcanic-intrusive complex providing the dominant sediments. In combination with the paleo-wind directions from the aeolian sandstones, the sediments are interpreted to be largely from the northwestern Jiuling mountain area and the northeastern areas.