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AbstractBeing located in Jinning County, Yunnan Province, approximately 103?E, 25?N, the Meishucun section has a long history of study, convenient accessibility, mild spring-like climate all the year round and good exposures of the relevant strata. In the particular area there occur monofacial transitional carbonate deposits of marine origin, yielding in great abundance both small shelly fossils and trace fossils, which are present in close association and in some cases on the same bedding surface. The sequence of biotic assemblages is clearly evident and can be used for wide intercontinental correlation.In the lower part of the Qiongzhusi Stage, stratigraphically higher, there appear the oldest trilobites, archaeostracods and Baltisphaeridiumcharacteristic of the Early Cambrian.During the last six years great progress has been made in the study of the particular section through lithostratigraphic, biostratigraphic, geochronological, magnetostratigraphic and seismostratigraphic approaches, thus making the Meischucun Stage and the Sinian?Cambrian boundary stratotype section in the Meishucun area a Chinese candidate for global stratotype section and point for the Precambrian?Cambrian boundary.

AbstractThe Sinian and Cambrian systems within the Yangtze stratigraphic province represent continuous deposits, and the strata above and below the Sinian?Cambrian boundary are rich in fossils. From all the relevant boundary sections, the Meishucun section in Jinning County, Yunnan Province serves as the stratotype section for the Sinian?Cambrian boundary and is the Chinese candidate for the global stratotype section and point for the Precambrian?Cambrian boundary. The present paper, with the various charts and tables, elaborates on several typical Sinian?Cambrian boundary sections and the distribution of fossils in them.In accordance with the characteristics of biological evolution, three biotas can be recognized for the period from the Late Sinian to the Early Cambrian. The first biota appeared in the Late Sinian, characterized by the presence of the soft-bodied metazoans; the second biota occurred during the Meishucun Stage of the early Cambrian, and is characterized by the appearance and prevalence of small shelly fossils from many different phyla; and the third biota came into existence during the Qiongzhusi Stage of the Early Cambrian; it is characterized by the first appearance and prevalence of trilobites.The Meishucun Stage of the Lower Cambrian can be divided into three fossil zones. The Sinian?Cambrian boundary is placed at the base of the first Anabarites?Circotheca?Protohertzina zone. According to isotopic dating by the Rb?Sr whole-rock isochron technique, the age of the Sinian?Cambrian boundary is inferred to be 610?10 Ma.