Chert-hosted small shelly fossils: expanded tool of biostratigraphy in the Early Cambrian.

Small shelly fossils (SSFs) are widely utilized for Cambrian biostratigraphy of shallow-water carbonates. The apparent linkage of SSFs to carbonate facies reflects an observational bias. Our study on the deeper siliceous facies of the Yangtze Craton in Zhejiang and Hunan provinces (China) reveals that SSFs also can be extracted from cherts. For this purpose a quick-etching method with weak hydrofluoric acid is applied. SSFs extracted from cherts are comparable with those from carbonates. Energy-dispersive X-ray spectroscopy analyses indicate a primary composition of SSFs of organic carbon and apatite. Hydrofluoric acid-processing can provide valuable biostratigraphic data of SSFs that are complementary to standard methods. [ABSTRACT FROM AUTHOR]