Mesoarchaean acidic volcanic lakes: A critical ecological niche in early land colonisation

Andrea Agangi, Axel Hofmann, Frantz Ossa Ossa, Dóra Paprika, Andrey Bekker

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

The antiquity of life in marine environments has been demonstrated, with examples of microfossils and stromatolites extending back to at least 3.5 billion years ago (Ga). In contrast, emerged land was likely a more challenging environment during the Archaean, and only sparse evidence of life in non-marine environments has so far been identified. Here we document the abundance of isotopically light carbon (with δ13C values from −46.6 to −31.3‰), diagnostic of a biogeochemical methane cycle or acetogenesis, in shale and sandstone deposited in ∼3 billion-years-old acidic volcanic lakes on the Kaapvaal Craton of southern Africa. A distinctive Al-rich mineral assemblage with abundant pyrophyllite in lacustrine sedimentary rocks bears similarity to modern volcanic rocks affected by circulation of hot acidic fluids. This is compounded with an enrichment of Ni, Mo, W, As and Cu in whole-rock analyses of sedimentary rocks, which is also observed in geothermal areas of modern volcanic environments. Analysis of early diagenetic pyrite in these sedimentary rocks indicates high nutrient level in the lake, which might reflect hydrothermal input with leaching of volcanic material. Despite the restricted and ephemeral nature of volcanic lakes, a highly productive and complex ecosystem established itself in this environment. Volcanic lakes during the Mesoarchaean thus served as an ecological niche for the development and diversification of microbial life on emerged continental landmasses.

Original languageBritish English
Article number116725
JournalEarth and Planetary Science Letters
Volume556
DOIs
StatePublished - 15 Feb 2021

Keywords

  • Dominion Group
  • early life
  • Kaapvaal Craton
  • Mesoarchaean

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