Sedimentology of Precambrian Depositional Systems: Understanding the Earth's Surface in Deep Time

前寒武纪沉积系统的沉积学：深入了解地球表面

• 批准号: RGPIN-2018-04051
• 负责人: Fralick, Philip
• 金额: $ 3.13万
• 依托单位: Lakehead University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=688701
• 关键词: Sedimentology; Precambrian; Depositional; Systems; Understanding

***Most people tend to view the natural world as constant. A storm may blow a tree down or a bluff may be slowly eaten away by the waves, but the oceans and the mountains are viewed as forever. When people think of forever in this way, they are approaching the concept from a human point of view, limited by our short lifespans. However, the oceans and mountains also have lifespans and these are much longer. Only twenty thousand years ago most of Canada was covered by ice. Everything we see today was either not here or, if it was large and solid, was all or mostly under the ice. The further back in time we go, the greater the difference from the present. Two thousand seven hundred million years ago the central area of Canada consisted of volcanic islands similar to the Caribbean region; North America did not exist; a world ocean dominated the planet; the most advanced life was bacteria; and the atmosphere had no oxygen. We know this because the rocks that were formed at this time from volcanic eruptions, and the sedimentary rocks produced by the erosion of the islands, occur as bedrock under large areas of central Canada. My research uses clues left behind in sedimentary rocks to discover what the geography looked like and what sedimentary processes were operating, when the Earth was a young planet. I am particularly interested in the composition of the atmosphere and ocean during the time period 3.0 to 1.4 thousand million years ago. In approximately the middle of this time period photosynthesizing organisms added significant amounts of oxygen to the atmosphere and oceans. I analyse minerals in sedimentary rocks that formed from chemicals precipitated in the ocean during this time period. These minerals grew on the bottom of the ocean and are now contained in sedimentary rocks. The composition of the minerals provides me with the information I need to form conclusions on how the chemistry of the ocean-atmosphere system developed through time. The importance of this work is not limited to understanding how the oceans and atmosphere were transformed over time. The chemistry of the surface of the Earth was a major control on the evolution of various forms of life on Earth. Understanding ocean-atmosphere chemistry is essential to unraveling life's early history.

***大多数人倾向于将自然世界视为恒定。暴风雨可能会吹树，或者悬崖可能会被海浪慢慢吞噬，但海洋和山区被视为永远。当人们永远以这种方式思考时，他们正在从人类的角度接近概念，受到我们短暂的寿命的限制。但是，海洋和山脉也有寿命，这些寿命更长。仅仅两万年前，加拿大大部分地区都被冰覆盖。我们今天看到的一切都不在这里，要么，如果它大而坚固，就在冰上或大部分。我们走的时间越远，与现在的差异越大。两七亿年前，加拿大的中部地区由与加勒比地区类似的火山岛组成。北美不存在；世界海洋主导地球；最先进的生活是细菌。而且气氛没有氧气。我们之所以知道这一点，是因为目前由火山喷发形成的岩石，以及岛屿侵蚀产生的沉积岩石，作为加拿大中部大区域的基岩出现。我的研究使用在沉积岩中留下的线索来发现地理的外观以及当地球是年轻星球时的沉积过程运作。我对3.0至1400万年前的大气和海洋组成特别感兴趣。在这段时间的大约中间，光合作用的生物体为大气和海洋增加了大量的氧气。我分析了这段时间内由海洋沉淀的化学物质形成的沉积岩中的矿物质。这些矿物质在海底生长，现在包含在沉积岩中。矿物质的组成为我提供了关于海洋 - 大气系统的化学如何随着时间发展的结论所需的信息。这项工作的重要性不仅限于了解海洋和气氛如何随着时间的流逝而变化。地球表面的化学反应是对地球各种生命形式的演变的主要控制。了解海洋 - 大气化学对于揭示生活的早期历史至关重要。