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Biological activities at the Archean submarine hydrothermal environments

太古代海底热液环境的生物活动

基本信息

批准号：
13440157
负责人：
KAKEGAWA Takeshi
金额：
$ 8.7万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Hydrothermal origin of life on the Archean seafloor is becoming a popular theory, besides the idea that the evolution of early biota took place at the submarine hydrothermal environments Abundant submarine hydrothermal sediments have been found in the Archean strata and there exists possibility that remnants of early biota and chemical fossils of their ecosystem were still preserved in these sediments. The main purpose of this study is to identify the remnants of early biota and their ecosystem based on the geological and geochemical ways. In this study, detailed geological surveys were conducted in two areas : the 2.7 Ga Abitibi Greenstone Belt and 3.2 Ga Pilbara Blocks in Australia. Other samples related to Archean submarine hydrothermal activities and modern hydrothermal activities were also subjects for the chemical analyses in this study. The followings are the notable findings from this study : specific hydrothermal alterations by carbon dioxide-rich fluids and mobilization of phosphorous from oceanic crust, age specific activity of methane-related biota and their association with magmatic activity and metal enrichments in organic matter by hydrothermal reaction. New ecological energy exchange system was also found in the modern hydrothermal sediments and its links to Archean ecosystem was also proposed. These achievements were already published in the several international and domestic journals, and also reported at international conferences as invited talks. New theory of biological evolution associated with the contemporary magmatic activity is also proposed from this study.

太古宙海底生命的热液起源说正在成为一种流行的学说，除了早期生物群的演化发生在海底热液环境之外，在太古宙地层中发现了丰富的海底热液沉积物，并有可能在这些沉积物中保存了早期生物群及其生态系统的化学化石的残留物。本研究的主要目的是基于地质和地球化学方法识别早期生物群的残留物及其生态系统。在这项研究中，在两个地区进行了详细的地质调查：澳大利亚2.7Ga Abitibi绿岩带和3.2Ga Pilbara区块。与太古宙海底热液活动和现代热液活动有关的其他样品也是本研究的化学分析对象。这项研究的显著发现如下：富二氧化碳流体的特定热液改造和洋壳磷的活化、与甲烷相关的生物群的特定年龄活动及其与岩浆活动和热液反应在有机质中的金属富集性的关系。在现代热液沉积中还发现了新的生态能量交换系统，并提出了与太古宙生态系统的联系。这些成果已在国内外多个期刊上发表，并作为特邀报告会在国际会议上作了报道。提出了与当代岩浆活动有关的生物演化新理论。