Microbially Induced Sedimentary Structures from the 2.9 Ga old Pongola and Witwatersrand Supergroups, South Africa

南非 2.9 Ga 老 Pongola 和 Witwatersrand 超群的微生物诱发沉积结构

• 批准号: 0345149
• 负责人: Nora Noffke
• 金额: --
• 依托单位: Old Dominion University Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-15 至 2008-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0345149&HistoricalAwards=false
• 关键词: Microbially; Induced; Sedimentary; Structures; 2.9

EARTH'S EARLIEST BACTERIA IN A SANDY MARINE ENVIRONMENT: FOSSIL MICROORGANISMS FROM THE 2.9 BILLION YEARS OLD PONGOLA AND WITWATERSRAND SUPERGROUPS, SOUTH AFRICAPI: Nora Noffke; Department of Ocean, Earth & Atmospheric Sciences; 4600 Elkhorn Avenue; Norfolk, VA 23529; [e-mail] and cyanobacteria form organic, carpet-like layers that cover large areas of coastal sediments. Such layers have been termed "microbial mats". In sandy marine sediments, microbial mats cause very characteristic sedimentary structures. These structures have been termed "microbially induced sedimentary structures - MISS", and they are known not only from modern marine environments, but from sandy sediments of all Earth ages. The fossil MISS include significant information about the ancient, mat-forming microorganisms, and therefore they also constitute a significant tool in deciphering the strange world of the earliest Earth, the Archean.Whereas many studies on Archean marine deposits focus on carbonate rocks or cherts, the PI follows a new approach by investigating sandstone successions in order to detect MISS. Therefore, the proposed study opens a new window in understanding Earth's earliest life and environments.A pilot study conducted by the PI in the Pongola Supergroup, South Africa, detected microbially induced sedimentary structures that provide evidence for the existence of filamentous bacteria forming microbial mats in 2.9 billion year old shelf environments - the oldest-known occurrence of microbial mats in siliciclastic (sandy) rocks (Noffke, Hazen & Nhleko, 2003). The structures include body fossils that resemble the cells of modern cyanobacteria, chloroflexi, or sulfur-oxidizing bacteria. The body fossils could indeed hint on the oldest cyanobacteria. Mineralogical, geochemical, and isotopic analyses are consistent with a biological origin of the structures. The follow-up investigations will elucidate the paleoenvironmental conditions that permit the development of microbial mats in the Archean. A detailed survey of MISS-bearing rock strata will document the distribution and variation of the ancient microbial mats. It will show, how different microbial mat types reflect the extreme life conditions characteristic for the Archean Earth.In addition, the study will set up a catalogue of MISS in order to compare the structures with those of younger Earth ages. The PI will organize a reference repository of MISS at Old Dominion University, which would serve the national and international geoscientific community for research and teaching.

多桑迪海洋环境中地球最早的细菌：来自29亿年前的蓬戈拉和威特沃特斯兰德超群的微生物化石，南非：诺拉诺夫克;海洋系，地球大气科学; 4600埃尔克霍恩大道;诺福克，弗吉尼亚州23529; [e-mail]。细菌和蓝藻形成有机的地毯状层，覆盖了大面积的沿海沉积物。这种层被称为“微生物垫”。在桑迪海洋沉积物中，微生物席造成了非常独特的沉积结构。这些结构被称为“微生物引起的沉积结构- MISS”，它们不仅在现代海洋环境中，而且在所有地球年龄的桑迪沉积物中都是已知的。MISS化石包含了关于古老的、席状微生物的重要信息，因此它们也构成了破译最早的地球--太古代的奇怪世界的重要工具。鉴于许多关于太古代海洋沉积物的研究集中在碳酸盐岩或燧石上，PI遵循一种新的方法，通过调查砂岩序列来检测MISS。因此，拟议中的研究为了解地球最早的生命和环境打开了一扇新的窗口。PI在南非Pongola超群进行的一项试点研究发现了微生物诱导的沉积结构，为丝状细菌在29亿年前的大陆架环境中形成微生物垫提供了证据-这是硅质（桑迪）岩石中已知最古老的微生物垫（Noffke，哈岑&Nhleko，2003年）。结构包括身体化石，类似于现代蓝藻，绿球藻或硫氧化细菌的细胞。尸体化石确实暗示了最古老的蓝藻。矿物学、地球化学和同位素分析与结构的生物起源一致。后续调查将阐明允许在太古代微生物席的发展的古环境条件。对含MISS岩层的详细调查将记录古代微生物席的分布和变化。它将展示不同的微生物垫类型如何反映太古代地球特有的极端生命条件。此外，该研究将建立一个MISS目录，以便将其结构与较年轻的地球年龄进行比较。PI将在Old自治领大学组织一个MISS参考资料库，为国家和国际地球科学界的研究和教学服务。