Biotic characteristics of the Sinian-Cambrian boundary beds in China and the boundary problems

Abstract

There is general agreement that the first appearance of various small shelly fossils should be used to help delineate the beginning of the Cambrian Period. The history of research on this stratigraphic topic in China is briefly outlined and leads on to a discussion of the boundary problem in the light of information available both inside and outside China. The sections across the Precambrian—Cambrian (Sinian—Cambrian) boundary are described with notes on fossils in: (1) Tianzhushan section, Yichang, Hubei; (2) Maidiping section, Emli, Sichuan; (3) Wangjiawan section, Jinning County, Yunnan; and (4) Kunyang section, Yunnan. This is followed by a consideration of the biotic characteristics of Sinian—Cambrian Period. The history of research on this stratigraphic topic in China is briefly outlined and leads on to a discussion of the boundary problem in the light of information available both inside and outside China. This is followed by a consideration of the biotic characteristics of Sinian—Cambrian boundary beds, with respect to stratigraphy as well as organic evolution. The Precambrian—Cambrian boundary in China is estimated to have an age of 615 ± 20 Ma. It is commented that the above sections are qualified to be important candidates for the selection of the Sinian—Cambrian boundary stratotype and are also important working reference sections for the international Precambrian—Cambrian boundary stratotype.