《Table 1 Establishment of the Ediacaran System and its historical evolutiona)》

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《Ediacaran integrative stratigraphy and timescale of China》

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a) Radiometric ages are in Ma.

The definition of the Sinian System has been modified multiple times since its first appearance in the literature more than 130 years ago（Table 2）.In 1882，the Sinian System was originally proposed to include the Cambrian and Precambrian strata that overlies the gneiss basement in eastern Liaoning.Later it was modified to include Cambrian-Ordovician strata（Peng et al.，2012）.In 1922，Grabau proposed that the Sinian System contains unmetamorphosed or slightly metamorphosed rocks between the Cambrian and Wutai series in Shanxi and Hebei provinces（Table 2）.Two years later，Lee and Chao（1924）defined the Sinian System to include the unmetamorphosed strata between the overlying Cambrian rocks and the underlying Huangling granite in the Yangtze Gorges area.They further subdivided it into three series，the lower series comprises the Nantuo sandstone（now the Liantuo Formation sandstone）and Nantuo diamictite，the middle and upper series comprise the Doushantuo and Dengying formations，respectively.The Sinian section in the Yangtze Gorges area then became the standard section of“Sinian System of South China”.After investigating the Precambrian sections in Jixian of Tianjin，Kao et al.（1934）proposed to classify the 9000 m thick of marine deposits overlying the metamorphosed rock basement into ten formations，and also included them in the Sinian System（Table2）.However，further research including radiometric dating indicates that the“Sinian System”in Jixian has a much longer duration and a much older age than the“Sinian System of South China”.At the 1975“Conference on the Chinese Sinian System”in Beijing，it was resolved to establish the Sinian Suberathem to include Precambrian strata overlying the metamorphosed basement，and to subdivide it into the Changchengian，Jixianian，Qingbaikouan，and Sinian systems.Several years later，the Sinian Suberathem was abandoned，and the Sinian System was formally defined to comprise the late Precambrian strata represented in the Yangtze Gorges area，with its lower boundary placed at the base of the Liantuo Formation sandstone（National Commission on Stratigraphy of China.1983）.However，Liu et al.（1991）proposed that the lower boundary of the Sinian System should be placed at the unconformity related to the Jinning Orogeny，Xue et al.（2001）suggested to place the boundary at the base of the Gucheng Formation diamictite，whereas Wang et al.（2001）proposed to place the boundary near the base of the member II black shale of the Doushantuo Formation in the Yangtze Gorges area，marked by the first appearance of the Doushantuo-type spiny acritarchs after the termination of the Nantuo glaciation（Table 2）.