白粘土
2.Strong acid in pH0.80～1.32 is first recognized and determined from the “white clay” for Meishan section A and B. The finding as more substantial evidence strongly supports the suggestion that a marine acidification event could occur at the span of the Permian-Triassic boundary, 251 million years ago, in our Earth history.
4.At that time,the by-products of salt processing such as mirabiliteand bloedite were as usual abandoned in pile in the pans,maximal thicknesssometimes reaching 4m. Some samples collected from the bottom of these tailaccumulations were dated by determining the isotope ~(14)C as 4.653±87a.
