The Middle Triassic Badong Formation

situated in Nanzhang

Hubei Province

is a set of mixed carbonate-terrigenous clastic sediments deposited mainly in a low energy tidal flat-lagoon environment.The sediments occurred in following seven types:1.lime-stone-clastic rocks interbeds;2.clastic rocks intercalated with limestons;3.limestones intercalated with clastic rocks;(4).carbonate appeared as cement in clastic rocks;5.terri-genous clastics distributed in carbonate matrix;6.terrigenous silts filled in pores of intra-clastic limestone;7.carbonate intraclasts distributed in terrigenous mud.