Climatic and oceanic controlled deposition of Late Ordovician-Early Silurian black shales on the North Yangtze platform, South China

Late Ordovician to earliest Silurian is an important geological period marked by large geological and biological events. However, the strata and fossils of this interval are not complete in many parts of the world. Based on studies of 43 sites in South China, in particular the continuous sections on the Yangtze platform, we recognize a complete succession including seven graptolite zones and two shelly faunas. In ascending order, the graptolite zones are the Dicellograptus complanatus, Dicellograptus complexus, Paraorthograptus pacificus (including Lower Subzone, Tangyagraptus typicus Subzone and Diceratograptus mirus Subzone), Normalograptus extraordinarius–Normalograptus ojsuensis, Normalograptus persculptus, Akidograptus ascensus and Parakidograptus acuminatus zones. The shelly faunas are the Foliomena–Nankinolithus and Hirnantia faunas, which may be correlated with D. complanatus Zone and N. extraordinarius–N. ojsuensis to part of N. persculptus zones respectively. The biozonation through this interval from the Yangtze region can be correlated with that of other parts of the world such as Dob's Linn in Scotland, Spain and Portugal, Thuringia–Saxonia–Bavaria, Bohemia, Poland, Kazakhstan, Kolyma, Malaya Peninsula, Yukon, Canadian Arctic Islands, Nevada, Argentina, Niger and Victoria, Australia. The Hirnantian Substage, which has been proposed by us recently, includes the N. extraordinarius–N. ojsuensis Zone, Hirnantia fauna and N. persculptus Zone. The base of the Hirnantian Substage is marked by the First Appearance Data (FADs) of N. extraordinarius and N. ojsuensis, which have been determined to be synchronous on a global scale.

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New paleoscolecid worms from the early Cambrian north margin of the Yangtze Platform, South China

Journal of Paleontology ◽

10.1017/jpa.2017.50 ◽

2017 ◽

Vol 92 (1) ◽

pp. 49-58 ◽

Cited By ~ 2

Author(s):

Yuning Yang ◽

Xingliang Zhang ◽

Yuanlong Zhao ◽

Yiru Qi ◽

Linhao Cui

Keyword(s):

South China ◽

New Genus ◽

Early Cambrian ◽

New Taxon ◽

Burgess Shale ◽

Yangtze Platform ◽

Mosaic Pattern ◽

The North ◽

Deposit Feeders ◽

Stage 4

AbstractThe Cambrian Yanwangbian assemblage (Series 2, Stage 4) in South Shaanxi, China, is one of the Burgess Shale–type faunas as it represents the only relatively diverse Cambrian biota from the north margin of the Yangzte Platform, South China. The paleoscolecids (Cycloneuralia) illustrated herein are one of the major components of the fauna, although they appear to be much less abundant than skeletonized fossils, according to available collections. A new taxon, Shaanxiscolex xixiangensis new genus new species, is described based on the scleritome pattern: each annulus has two rows of alternating Hadimopanella-type plates positioned close to the borders, and a mosaic pattern of microplates occurs between the plates and within intersegmental furrows. The occurrence of the new taxon confirms a fairly diversified and widespread distribution of paleoscolecidan worms recognized in the early Cambrian of South China. Moreover, the ecology of paleoscolecids is reappraised based on burial position of the S. xixiangensis and gut contens of Cambrian taxa from South China, hinting that paleoscolecids (at least some taxa) were both deposit feeders and carnivores, as well as active bioturbators in the substrates of the Cambrian sea, which sheds new light on the ‘Cambrian Substrate Revolution.’

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