Lantian formation

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Lantian formation
Stratigraphic range: 635–577Ma
Location
Location South China

The Lantian formation is a 150-meter-thick sequence of rocks deposited in southern China during a 90-million-year epoch in the Ediacaran period.[1] Its algal macrofossils are the oldest large and complex fossils known.[1]

Sedimentology[edit]

The rocks were deposited in shallow seas, in the photic zone yet below storm wave base[clarification needed],[2] yet were deposited in predominantly anoxic conditions. The fossils are located on the bedding planes, and are randomly oriented.[1]

The lowest part of the formation consists of a cap dolostone, marking the end of the Marinoan glaciation and start of the Ediacaran. Above this is black shale containing the Lantian biota fossils. Above this are layers of dolomite, and shale followed by limestone. The highest part of the formation is black shale again. Above the formation is the Piyuancun formation consisting of silicious rock. The Lantian formation overlies diamictite from the Cryogenian.[3]

Taphonomy[edit]

The fossils are preserved as carbonaceous films in a Burgess Shale type preservational fashion.[1]

Age[edit]

Originally presumed to be Cambrian in age,[1] the formation is now correlated with the Doushantuo formation, with an overlying formation also falling in the Ediacaran period.[2]

References[edit]

  1. ^ a b c d e Narbonne, G. M. (2011). "Evolutionary biology: when life got big". Nature 470 (7334): 339. Bibcode:2011Natur.470..339N. doi:10.1038/470339a.  edit
  2. ^ a b Yuan, X.; Chen, Z.; Xiao, S.; Zhou, C.; Hua, H. (2011). "An early Ediacaran assemblage of macroscopic and morphologically differentiated eukaryotes". Nature 470 (7334): 390–3. Bibcode:2011Natur.470..390Y. doi:10.1038/nature09810. PMID 21331041.  edit
  3. ^ supplementary figure 4 of doi:10.1038/nature09810