Origin of ooids, peloids and micro-oncoids of marine ironstone deposits in Western Siberia (Russia)

•Ooidal ironstone deposits were formed by both abiogenic and biogenic processes.•Physico-chemical conditions of the porewater regulated abiogenic precipitates.•Microbial mediation is required for the authigenic mineral formation.•Some mineral inclusions within oncoids formed by the iron-reducing bacterial activity.•Abundant intraclast is indicative of tectonic events.•Mineral geochemistry supports the hydrothermal source of iron and other metals.