Geochemical evidence for terrestrial ecosystems 2.6 billion years ago
Geochemical evidence for terrestrial ecosystems 2.6 billion years ago
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DOI：
10.1038/35046052
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发表时间：
2000-11-30
期刊：
影响因子：
64.8
通讯作者：
Ohmoto, H
中科院分区：
文献类型：
--
作者：
Watanabe, Y;Martini, JEJ;Ohmoto, H
微生物至少从38亿年前（3.8 Gyr）开始就在海洋中繁盛（1,2），但目前尚不清楚它们是何时首次在陆地上定居的。一些富Au/ u砾岩和2.3-2.7 Gyr时代古土壤中的有机质被认为是陆生生物的残留物（3-5）。一些2.7 gyr的叠层石也被认为是陆生生物创造的结构（6-7）。然而，这些有机物是本地的还是外源的，以及这些叠层石是在海洋还是淡水中形成的，一直存在争议。因此，目前最古老的陆地生物无可争议的遗迹是来自美国亚利桑那州的1.2 gyr的微化石(8)。在南非的姆普马兰加省（东德兰士瓦省）发现了不同寻常的含碳古土壤（古土壤）。本文报道了该有机质及其寄主岩石的产状、元素比（C、H、N、P）和同位素组成。这些数据表明，这些有机物很可能代表2.6至2.7 Gyr以前在土壤表面发育的微生物席的残留物。这使得陆地生物量的发展比以前报道的要早14亿年以上。
Microorganisms have flourished in the oceans since at least 3.8 billion years (3.8 Gyr) ago(1,2), but it is not at present clear when they first colonized the land. Organic matter in some Au/U-rich conglomerates and ancient soils of 2.3-2.7 Gyr age has been suggested as remnants of terrestrial organisms(3-5). Some 2.7-Gyr-old stromatolites have also been suggested as structures created by terrestrial organisms(6-7). However, it has been disputed whether this organic matter is indigenous or exogenic, and whether these stromatolites formed in marine or fresh water. Consequently, the oldest undisputed remnants of terrestrial organisms are currently the 1.2-Gyr-old microfossils from Arizona, USA(8). Unusually carbonaceous ancient soils-palaeosols-have been found in the Mpumalanga Province (Eastern Transvaal) of South Africa(9). Here we report the occurrences, elemental ratios (C, H, N, P) and isotopic compositions of this organic matter and its host rocks. These data show that the organic matter very probably represents remnants of microbial mats that developed on the soil surface between 2.6 and 2.7 Gyr ago. This places the development of terrestrial biomass more than 1.4 billion years earlier than previously reported.