BIOGEOCHEMISTRY: ON PHOTOSYNTHESIS 3.4 BILLION YEARS AGO

BIOGEOCHEMISTRY: ON PHOTOSYNTHESIS 3.4 BILLION YEARS AGO: "From this reconstruction of sedimentary environments, the authors conclude that the mat-like organic laminations in black chert apparently had ecological control over their distribution. The laminations are only present in banded chert, deposited in a shallow marine environment, within the depth to which light could penetrate the water column (the euphotic zone). The distribution of these distinctive organic morphologies is best explained by their being of biological origin. This result takes our understanding of early Archaean biota beyond the hydrothermal debate, and greatly improves the case for the existence of photosynthetic organisms in the early Archaean.(4,5)"