Sedimentary organic matter deriving from tubes of sabelliditids,
vendotaenids, sapropelic
films and kerogens was extracted by acid processing from Upper Vendian
siliciclastic successions in the
East European Platform. Elemental composition obtained by instrumental
neutron activation analysis
(INAA) displays the increasing cobalt (Co) concentration from 1 ppm at
the bottom of Upper
Vendian succession to about 800 ppm in the uppermost part near the
Precambrian–Cambrian boundary.
This distribution is recorded in all studied successions and is not
related to resistant minerals that
survived acid treatment. The enrichment in Co and other metals in
the sedimentary organic matter is
inferred to be caused by the bloom of cyanobacterial microbiota,
and bonding of metals in decaying
sedimentary organic matter during pre-burial bacterial reworking and
post-burial early diagenesis in a
low energy, stagnant depositional basin during Kotlin times. The
positive Ceanom in probable benthic
sabelliditids, and the exceptional preservation of sedimentary
organic matter from Kotlinian strata,
indicate the anaerobic conditions during their sedimentation.
Clear correlations between 87Sr/86Sr,
δ13C and Co imply the secondary isotopic signatures of
Sr and C
in sedimentary organic matter
deriving from a restricted epicontinental marine basin.