Geochemical evidence for terrestrial ecosystems 2.6 billion years ago

Yumiko Watanabe, Jacques E.J. Martini, Hiroshi Ohmoto

Research output: Contribution to journalArticle

158 Citations (Scopus)

Abstract

Microorganisms have flourished in the oceans since at least 3.8 billion years (3.8 Gyr) ago, 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. Some 2.7-Gyrold stromatolites have also been suggested as structures created by terrestrial organisms. 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. Unusually carbonaceous ancient soils - palaeosols - have been found in the Mpumalanga Province (Eastern Transvaal) of South Africa. Here we report the occurrences, elemental ratios (C, H, N, P) and isotopic compositions of tiffs 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.

Original languageEnglish
Pages (from-to)574-578
Number of pages5
JournalNature
Volume408
Issue number6812
DOIs
Publication statusPublished - 2000 Nov 30

ASJC Scopus subject areas

  • General

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