Roles of Hydrothermal Processes in Biological Evolution

该研究项目的主要目的是了解地球早期主要生物事件的原因，特别是20亿年前真核生物的首次出现和5.5亿年前大型海洋动物的首次出现。本文主要通过对4个地区(A)加拿大安大略南部地区（2.8 ~ 1.8 Ga层序）、加拿大纽芬兰布林半岛（570 ~ 520 Ma层序）、法国诺曼底地区（600 ~ 500ma层序）和南非Kaapvaal克拉通（3.0 ~ 2.0 Ga层序）野外采集的约1000个岩石标本进行系统的有机质、矿物和岩石地球化学调查来实现这一目标。我们的调查有以下主要发现：(1)。根据目前流行的理论，生物物种的第一次主要划分（真核生物、细菌和真细菌）是由大约20亿年前大气中二氧化碳的急剧上升引起的。然而，我们已经发现了各种各样的地球化学证据，表明生物物种的主要划分和含氧大气的形成在30亿年前就已经发生了。大约5.5亿年前的“生物大爆炸”可能是由全球海水化学变化（例如，磷酸盐通量的增加）和气候引起的。在整个地质时期，影响海洋生物活动的主要海洋水化学变化可能是由大陆地理形态的变化（如超级大陆的断裂）和洋中脊海底热液活动的变化引起的。这些变化是由地幔对流模式的变化引起的。我们的一些调查结果已经在国家和国际科学会议上发表（大约25次发表）。已在主要国际期刊上发表（或出版）5篇论文，并正在编写与本项目有关的20多篇论文。少

The main objective of this research project was to understand the causes for major biological events in the early Earth, especially the first appearances of eukaryotes around 2 billion years ago and of large marine fauna around 550 million years ago. This objective was mostly pursued from systematic geochemical investigations of organic matter, minerals and rocks in about 1000 rock specimens that were collected during our field surveys in 4 areas : (A) the southern Ontario district, Canada (2.8-1.8 Ga sequence), (B) the Burin Peninsula, Newfoundland, Canada (570-520 Ma sequence), (C) the Normandy district, France (600-500Ma sequence), and (D) the Kaapvaal Craton, South Africa (3.0-2.0 Ga sequence).Our investigations have resulted in the following major findings :(1). According to a currently popular theory, the first major division of biological species (Eukaryotes, Bacteria, and Eubacteria) were caused by a dramatic rise of the atmosphericO_2 around 2.0 billion years ago. However, we … More have discovered various lines of geochemical evidence suggesting that the major division of biological species and the development of an oxic atmosphere had already taken place by 3.0 billion years ago.(2). "The great biological explosion" of around 550 million years ago was probably caused by the global changes in the ocean water chemistry (e.g., an increase in the phosphate flux) and climate.(3). The major changes in the ocean water chemistyr that affected the biological activity in ocean through geologic time were probably caused by the changes in the geographical configuration of continents (e.g., breaking of super continents) and in submarine hydrothermal activity in mid ocean ridges. These changes were in turn caused by changes in the convective patterns in the mantle.Some of the results from our investigations have already been presented at national and international scientific meetings (about 25 presentations). Five papers have been published (or in press) in major international journals, and about 20 more papers related to this project are in preparation. Less