| Microbialite of anoxic condition from Permian-Triassic transition in Guizhou,China |
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| 作者姓名： | WU YaSheng JIANG HongXia YANG Wan & FAN JiaSong Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China |
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| 作者单位： | WU YaSheng1，JIANG HongXia1，YANG Wan2 & FAN JiaSong1 1 Institute of Geology and Geophysics，Chinese Academy of Sciences，Beijing 100029，China; 2 Department of Geology，Wichita State University，1845 Fairmount，Wichita，KS 67260，USA |
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| 基金项目： | 国家自然科学基金;国家重点实验室基金;中国科学院重点实验室基金 |
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| 摘 要： | Spherical microfossils are present in the Hindeodus parvus zone of the Lower Triassic in Ziyun,Guizhou Province. They generally range from 0.15 to 0.30 mm across,with micritic wall and filled by micro-sparry calcites,and are evenly scattered in micritic matrix. Their abundance makes the rock as-signed to microbialites. The accompanied organisms include ostracods and algal mat,but no gastro-pods or bivalves. Presence of small (<7 μm) pyrite framboids indicates that this bed formed in anoxic conditions. In some sections,this bed is overlain and underlain by tidal-flat micritic limestone with microgastropods and small burrows. Occurrence only in deposits on reef top indicates that the micro-bial organism was benthic,and needed sunlight in life. The size of the microbial fossil exceeds that of any bacteria or cyanobacteria. Thus,it does not belong to these two phyla. It may belong to lower green algae,and is assigned to a new species in a new genus,Ziyunosphaeridium sinensis gen. et sp. nov. Up to now,the rocks described as microbialites from the Permian-Triassic transition include six types: (1) porous micritic limestone such as that descried from Japan by Sano and Nakashima (1997),(2) limestone with rich globular microfossils such as that described from the Nanpanjiang Basin in China by Lehrmann (1999),(3) dendroidal limestone such as that described from the vicinity of Chongqing by Kershaw et al. (1999),(4) spherical microbial limestone adapted to anoxic environments described from Ziyun,Guizhou reported in this paper,(5) limestone with cyanobacterial fossils such as that described by Wang et al. (2005),and (6) stromatolites. All these microbialites are not reefs in the proper sense,and the argument that Permian reef ecosystems extended into the Mesozoic is incorrect.
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| 收稿时间： | 9 June 2006 |
| 修稿时间： | 21 December 2006 |
Microbialite of anoxic condition from Permian-Triassic transition in Guizhou, China |
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| WU YaSheng,JIANG HongXia,YANG Wan & FAN JiaSong Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing ,China, .Microbialite of anoxic condition from Permian-Triassic transition in Guizhou,China[J].Science in China(Earth Sciences),2007,50(7):1040-1051. |
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| Authors: | WU YaSheng JIANG HongXia YANG Wan FAN JiaSong |
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| Institution: | 1. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
2. Department of Geology, Wichita State University, 1845 Fairmount, Wichita, KS 67260, USA |
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| Abstract: | Spherical microfossils are present in the Hindeodus parvus zone of the Lower Triassic in Ziyun, Guizhou Province. They generally range from 0.15 to 0.30 mm across, with micritic wall
and filled by micro-sparry calcites, and are evenly scattered in micritic matrix. Their abundance makes the rock assigned
to microbialites. The accompanied organisms include ostracods and algal mat, but no gastropods or bivalves. Presence of small
(<7 μm) pyrite framboids indicates that this bed formed in anoxic conditions. In some sections, this bed is overlain and underlain
by tidal-flat micritic limestone with microgastropods and small burrows. Occurrence only in deposits on reef top indicates
that the microbial organism was benthic, and needed sunlight in life. The size of the microbial fossil exceeds that of any
bacteria or cyanobacteria. Thus, it does not belong to these two phyla. It may belong to lower green algae, and is assigned
to a new species in a new genus, Ziyunosphaeridium sinensis gen. et sp. nov. Up to now, the rocks described as microbialites from the Permian-Triassic transition include six types:
(1) porous micritic limestone such as that descried from Japan by Sano and Nakashima (1997), (2) limestone with rich globular
microfossils such as that described from the Nanpanjiang Basin in China by Lehrmann (1999), (3) dendroidal limestone such
as that described from the vicinity of Chongqing by Kershaw et al. (1999), (4) spherical microbial limestone adapted to anoxic
environments described from Ziyun, Guizhou reported in this paper, (5) limestone with cyanobacterial fossils such as that
described by Wang et al. (2005), and (6) stromatolites. All these microbialites are not reefs in the proper sense, and the
argument that Permian reef ecosystems extended into the Mesozoic is incorrect.
Supported by the National Natural Science Foundation of China (Grant No. 40472015) and the State Key Laboratory of Modern
Paleontology and Stratigraphy (Grant No. 053102), as well as the Key Laboratory for Minerals and Resources, the Chinese Academy
of Sciences |
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| Keywords: | Microbialites reefs Permian-Triassic boundary mass extinction end-Permian |
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