Photozoan carbonate factory nourished by cyanobacterial bloom of the Cambrian Miaolingian: an example from the Wolongshan
Author:
Affiliation:

Clc Number:

Fund Project:

  • Article
  • |
  • Figures
  • |
  • Metrics
  • |
  • Reference
  • |
  • Related
  • |
  • Cited by
  • |
  • Materials
  • |
  • Comments
    Abstract:

    Describing, characterizing, and interpreting the wide variety of carbonate rocks represents a major challenge. Carbonate factories are referred to as production systems. The original definition refers to the clear neritic marine environment with a depth of less than 15 m in which most of carbonate producers assembled. Subsequently, a double subdivision of the shallow carbonate production system has been proposed based on the energy source, i.e, the photozoan and heterozoan factories, which represents a conceptual advance. Along with a deeper understanding of styles of carbonate precipitation, a threefold subdivision of the benthic carbonate production systems augmented with knowledge of the carbonate factory principle has been proposed on a geologic scale, i.e. ① the T- factory, in which the T is derived from tropical or “top- of- the- water- column”; ② the C- factory, in which the C stands for cool- water or controlled precipitation; and ③ the M- factory, in which M represents microbial, micrite, or mud- mound. Two aspects characterize the carbonate factory of the Cambrian Miaolingian: the first is the photozoan, the second is the microbial (the nourished by cyanobacterial bloom).Therefore, two particular carbonate factories could be differentiated i.e, the photozoan T- factory dominated by radial ooids that are induced by photosynthetic biofilms, and the photozoan M- factory dominated by microbial reefs that are built by cyanobacterial mats and also occupied the shallow environments normally filled by the T- factory. The Gushan Formation of the Cambrian Miaolingian at the Wolongshan section in Shouxian County of Anhui Province in southern North- China Platform makes up a third- order sequence bound by drowning unconformity that is marked by an upward shoaling succession from the shelf muddy shales of the condensed section to the oolites covered by microbial reefs (leiolites) of the forced regressive system tract. A sedimentary succession from a grain bank predominated by microbial radial ooids to a microbial reef predominated by leiolites constitute the forced regressive system tract of this third- order sequence. Within the dense and dark micrites making up the core and the cortex of radial ooids as well as the clump or clot among ooids there is high- density preservation of filamentous Girvanella that is likely analogous to the modern cyanobacterium Plectonema, which demonstrate that these radial ooids are products induced by photosynthetic biofilms and further delegate a particular photozoan T- factory. Within the leiolites making up the microbial reef overlying the oolite that represent the photozoan T- factory, the high- density preservation of filamentous Girvanella that are more than one half of volume indicates that this set of microbial reefs represents a particular photozoan M- factory. Thus, a special evolutionary succession from a photozoan T- factory to a photozoan M- factory was formed in the calcite sea with the cyanobacterial bloom of the Cambrian Miaolingian under the atmosphere with the highest content of carbon dioxide and relative high content of oxygen. These observations and research provide a rare example and an insight into the further understanding of a photozoan factory of microbial carbonates of the Cambrian Miaolingian that is formed by organomineralization linked to the cyanobacterial bloom, which coincided with metazoan radiation that benefited from the evolution of biomineralization.

    Reference
    Related
    Cited by
Get Citation

Mei Mingxiang.2021. Photozoan carbonate factory nourished by cyanobacterial bloom of the Cambrian Miaolingian: an example from the Wolongshan[J]. Acta Geologica Sinica,95(12):3571-3591

Copy
Share
Article Metrics
  • Abstract:
  • PDF:
  • HTML:
  • Cited by:
History
  • Received:July 04,2020
  • Revised:September 02,2020
  • Adopted:December 03,2020
  • Online: December 30,2020
  • Published: