Pedogenic siderites fossilizing Ediacaran soil microorganisms on the Baltica paleocontinent

Abstract

AbstractEdiacaran siderite-bearing sedimentary rocks from the western part of the East European craton exhibit features typical of redoximorphic paleosols, including pedogenic siderite (e.g., sphaerosiderite) with uniform and negative δ18O and highly variable δ13C values. The siderite precipitated in water-logged soils in a hot and humid climate, and represents a rare example of pedogenic siderite formed before the rise of vascular plants. Morphology of soil microorganisms was preserved in three dimensions due to the early siderite precipitation. These are mainly filamentous and tube-like threads, which might belong to cyanobacteria or fungi, and spherical structures resembling green algae. This microbial life fostered development of strongly reducing soils in tropical wetlands on the Baltica paleocontinent. The Ediacaran sediments of the western East European craton, traditionally regarded as marine, are reinterpreted as containing sections affected by freshwater conditions, documenting the presence of microbial life on the Ediacaran land.