On the formation age and developing process of Yong'an Stone Forest

摘要

Several tuffaceous rock samples, collected from different elevations at Yong'an Stone Forest,were measured using Uranium-series disequilibrium method. The results showYong'an Stone Forest was formed approximately 450 ka ago, during the Pleistocene epoch, and about 1 million years later than the Lunan Stone Forest. These results are interpreted in the context of the history of the Yong'an area geologic structure and the evolution process of the surrounding Minjiang River Basin. In the process of gradual weathering and erosion of the rock overlying on Carboniferous and Permian, Yong'an Stone Forest is formed accompanied by uplift of crust,in the background of Minjiang river drainage area formation and Dahu basin under erosion since Quaternary.