Change of marine environment based on analysis of Early-middle Triassic radiolarians

基于早中三叠世放射虫分析的海洋环境变化

基本信息

批准号：
07640625
负责人：
YAO Akira
金额：
$ 0.26万
依托单位：
Osaka City University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07640625/
关键词：
Lower-Middle Triassic radiolarian fossil assmblage marine environment siliceous claystone bedded chert

项目摘要

This study aimed to reconstruct the Early-Middle Triassic marine environment of the Panthalassa region on the basis of radiolarian research. Firstly, field work and rock sampling were carried out in the continuous stratigraphic sections of the lower to Middle Triassic siliceous sequence of the Mino Terrane, central Japan. Secondly, the faunal composition of the Early-Middle Triassic radiolarian assemblages was examined and compared with the Late Permain and Jurassic radiolarian assemblages, and petrographical features of siliceous rocks were described.The lower Triassic is mainly composed of siliceous claystone with thin black mudstone layrs in which radiolarian remains are rare and their variety is very low. The Middle Triassic mainly consists of red bedded chert sequence in which Mesozoic type radiolarians are abundantly contained and their variety becomes higher upward. The lower Triassic siliceous claystone gradually changes to the Middle Triassic bedded chert.On the other hand, the Upper Permian of the Mino Terrane excluding carbonate facies is represented by bedded chert sequence in which the highly varied Paleozoic type radiolarians are contained.On the basis of above mentioned results, it is considered that the marine environment of the low-latitudinal Panthalassa region during Early Triassic time was affected by the worldwide anoxic event, and that no bedded chert of the Lower Triassic depended on the low productivity of radiolarians. The lithologic change from the Early Triassic siliceous claystone to the Middle Triassic bedded chert shows that the high productivity of radiolarians recovered during Middle Triassic time. The Middle Triassic red bedded chert is considered to be formed under the oxic environment. It is concluded that the large scaled faunal change of radiolarians through Late Permian to Middle Triassic time was controlled by the marine environmental change.

这项研究旨在基于放射线研究，重建Panthalassa地区的早期中型三叠纪海洋环境。首先，在日本中部Mino Terrane的下部至中部三叠纪硅质序列的连续地层层中进行了现场工作和岩石采样。其次，检查了早期中型三叠纪放射性放射性组合的动植物组成，并将其与晚期的Permain和侏罗纪放射性放射性组合进行了比较，并描述了硅质岩石的岩石学特征。下三叠纪的下三叠纪的岩岩特征主要由硅质粘土石组成，由薄薄的黑色泥石石组成，其稀有的是稀有的。中间三叠纪主要由红色床的裂缝序列组成，其中大量的放射虫含量丰富，其品种变得更高。下部三叠纪的硅质粘土岩石逐渐变成中间三叠纪床的chert。另一方面，不包括碳酸盐相的米诺地层的上二叠纪由层状的切口序列表示，高度多样的古生代式放射性人在上述结果中所包含的高度范围，它被认为是在海上的基础。受到全球缺氧事件的影响，并且没有下三叠纪的层状chert取决于放射性人的生产力低。从早期的三叠纪硅质粘土岩到中间三叠纪床的裂缝的岩性变化表明，在中间三叠纪时间恢复了放射性虫的高生产率。中间三叠纪红床的缝隙被认为是在塞环境下形成的。结论是，海洋环境变化控制了放射性二叠纪人通过晚期到中三叠纪时间的较大缩放的动物变化。