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Did radiolarians become extinct at the Paleozoic/Mesozoic boundary? - The paleontological study of the Earliest Triassic radiolarians

放射虫是否在古生代/中生代边界灭绝了？

基本信息

批准号：
16340160
负责人：
TAKEMURA Atsushi
金额：
$ 8.77万
依托单位：
Hyogo University of Teacher Education
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16340160/
关键词：
Radiolaria Paleozoic Mesozoic P T boundary New Zealand Arrow Rocks Mass extinction bedded chert

项目摘要

The largest mass extinction event in earth history occurred at the Permian/Triassic boundary. Radiolarians, representative of Paleozoic to Mesozoic oceanic plankton with siliceous skeletons, drastically changed from Permian to Triassic time. The details of this change, however, remain unclear, because of the global lack of radiolarian-bearing pelagic sediments of Earliest Triassic age. The research group including the head investigator discovered an exceptional pelagic Permian-Triassic boundary sequence exposed at Arrow Rocks (Oruatemanu Island), a small islet at Northland, North Island of New Zealand. In this research project, the paleontological study of Earliest Triassic (mainly Early Induan) radiolarians was made to clarify the detailed faunal change of radiolarians across the P/T boundary.Relatively well-preserved radiolarians occurred in about 10 horizons within Griesbachian (early Induan) and early Dienerian (late Induan) chert sequence from Arrow Rocks. More than 40 species were discriminated among these radiolarians and about 20 species were reported and/or described (Takemura and Aono, 2007 ; Takemura et al., 2007). The head investigator had described the other species and prepares to submit the taxonomic paper.The Earliest Triassic radiolarian faunas include Entactinarians, Latentifistularians and Albaillellarians, all of which are components of Permian radiolarian faunas. Many species are the quite same one as Permian, and therefore they survived across the P/T boundary. Primitive Nassellaria, which are representative of Mesozoic and Cenozoic faunas, occurs in late Induan (Kamata et al., 2007). The radiolarian fauna had changed gradually around P/T boundary and within Earliest Triassic. This faunal change may be influenced by the double oceanic anoxic events detected from the Oruatemanu Formation (Hori et al., 2007). The Arrow Rocks research monograph (Sporli et al. (eds.), 2007) was published as one of the result of this research project.

地球历史上最大的生物灭绝事件发生在二叠纪/三叠纪的交界处。放射虫是古生代至中生代具有硅质骨骼的海洋浮游生物的代表，从二叠纪到三叠纪发生了巨大的变化。然而，这种变化的细节仍然不清楚，因为全球缺乏早三叠世时代的放射虫浮游沉积物。包括首席调查员在内的研究小组在新西兰北岛北岛的一个小岛Arrow Rocks（Oruatemanu岛）发现了一个特殊的中上层二叠纪-三叠纪边界序列。通过对早三叠世（主要是早印度世）放射虫的古生物学研究，阐明了P/T界线上放射虫的动物群变化，在Arrow Rocks的Griesbachian（早印度世）和Dienerian（晚印度世）燧石层中约10个层位中发现了保存较好的放射虫。在这些放射虫中鉴别出超过40个物种，并且报道和/或描述了约20个物种（Takemura和Aono，2007 ; Takemura等人，2007年）。早三叠世放射虫动物群包括Entactinarians、Latentifistularians和Albaillellarians，它们都是二叠纪放射虫动物群的组成部分。许多物种与二叠纪完全相同，因此它们跨越了P/T边界。原始织纹螺属（Nassellaria）是中、新生代动物群的代表，出现在印度纪晚期（Kamata et al.，2007年）。在P/T界线附近和早三叠世之内，放射虫动物群逐渐发生变化。这种动物群的变化可能受到从Oruatemanu组检测到的双重海洋缺氧事件的影响（Hori等人，2007年）。Arrow Rocks研究专著（Sporli等人（编辑），2007年，作为该研究项目的成果之一发表。