Interaction between Geosphere and Biosphere in the Early Paleozoic of the Tethys

特提斯早古生代地圈与生物圈的相互作用

基本信息

批准号：
12573008
负责人：
MATUMOTO Ryo
金额：
$ 9.79万
依托单位：
THE UNIVERSITY OF TOKYO
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2003
项目状态：
已结题

项目摘要

This march project covers the environmental change and biotic evolution in the Uppermost part of the Precambrian to the Lower Paleozoic. The methods of study includes 1. Field work in Iran and south China, 2, Observation of samples under microscope, 3. Geochemical analysis of samples for trace element concentrations, carbon and strontium isotopic ratio and biomarkers. Main highlights of individual research program am as follows.1.Environment and evolution in the Uppermost Precambrian ; Typical glacier deposits (diamictite of the Marinoan Ice Age) well develop in the South China platform. The diamictite is overlain by ca.4 m thick dolomite bed. The dolomite bed is considered as "Cap Carbonate" immediately after the "Snowball Earth". Detailed petrographic and chemical analysis of the dolomite has revealed that the dolomite was formed as an accumulation of peloids of primary dolomite under methane induced anoxic deep ocean environment, Another ice age was indicated by isotopic evidence at about 50 meters above the dolomite. Black shale between the two ice ages contains common chert nodules which yield abundant remains of microbial activity.2.The Ordovician-Silurian boundary and the Upper most part of the Devonian were also the major targets of the project. As for the former, we found new outcrop in South China, and observed continuous carbonate bed near the boundary within black shale. For the latter, clay mineral composition, organic material and isotopic analysis has strongly suggested that dissociation of gas hydrates must have played an important role in drastic change of global environments

这个3月的项目涵盖了前寒武纪至下古生代的前面部分的环境变化和生物进化。研究方法包括在伊朗和南部进行的1次现场工作，2，在显微镜下观察样品，3。对痕量元素浓度，碳和同位素比率和生物标志物的样品的地球化学分析。单个研究计划的主要亮点如下。1。在前寒武纪的环境和进化；典型的冰川沉积物（大麻冰河时代的二毫米）在中国南部平台发展。二氧化氢岩覆盖在Ca.4 m厚的白云岩床上。白云岩床在“雪球”之后立即被视为“碳酸盐”。白云石的详细岩石学和化学分析表明，在甲烷诱导的缺氧深海环境下，白云岩是原代白云岩的恒频的积累，由同位素证据表明了另一个冰期，在该白云岩高约50米处。两个冰河时代之间的黑色页岩包含常见的切口结节，产生了微生物活性的丰富残留物。至于前者，我们在中国南部发现了新的露头，并观察到黑色页岩边界附近的连续碳酸盐床。对于后者，粘土矿物质成分，有机材料和同位素分析强烈表明，气体水合物的解离必须在全球环境的急剧变化中发挥重要作用