The apparent increase of carbonaceous macrofossils through the Proterozoic Eon is likely a result of combined biological and environmental evolution.
This structure is very similar to kerogens found in carbonaceous meteorites.
The distinguishing feature of the lowermost sequence is the presence of coal or carbonaceous shale within alluvial and lacustrine strata.
This facies commonly occurs associated with carbonaceous shale and laminated sandstone.
Cross-bedding, channel-fill structures, red colouration, carbonaceous material, desiccation cracks and raindrop pits indicate that these rocks were deposited in a terrestrial environment.
Some beds contain carbonaceous fragments, and the remains of large roots are found underlying thick coal beds.
It is overlain by the lower shale member, which consists of interbedded carbonaceous shale and lignite that accumulated in coastal marsh and swamps landward of the shoreline.
Based on meteorite studies, astronomers recognize that NEAs have diverse compositions, including silicate, carbonaceous and hydrocarbon-bearing, metallic, and ice-bearing materials.
In Proterozoic carbonaceous fossils, ultrastructural and biochemical characters are unavailable, and anatomical and reproductive structures are uncommon.
Other fossil seed, leaf, beetle, ostracod, snail and fish remains come from a carbonaceous siltstone that represents a local waterlogged habitat.