Cambrian carbonate rocks in Tongreni-Fenghuang-Sandu-Danzhai regionbelongs to front slope facies of platform
and is in optimal position for mer-cury and oil accumulation. The diagenesis of the carbonate rocks include bio-genic agency
cementation
compaction
early-stage dissolution
neomorphsmi
dolomitization
pressure solution
metasomatism and late-stage dissolution.The early-stage dissolution and dolomitization took place in the Devonian-Carboniferous Periods and are favourable for oil accumulation; the latestage dissolution happened in Late Cretaceous and is favourable for mercuryaccumulation.