A Tide and Storm- Influenced Shoreline and Inner Shelf Sedimentary Sequence-Ruyang Group (Precambrian) of Western Henan

Ruyang Group, consisting of the Yunmengshan, Baicaoping, ;and Beidajian formations in an sacend-ing order. is the first sedimentary sequence overlying the Precambrian volcanic rocks in western Henan>which is geologically situated on the southern margin of North China Platform. Detailed facies and fades as-socia.tion analyses show that Ruyang Group was formed in tide- and storm-influenced coastal and innershelf environments. The group can be divided into nine main facies coarse-grained sandstone/conglomerate(F₁)，trough crossbedded sandstone(F₂)，compound crossbedded snadstone(F₃)，giant planarcross;bedded sandstone(F₄)，hummocky cross- stratified sandstone(F₅)，flat bedded sandstone(F₆)，low-angle crossbedded sandstone ( F₇)，interbedded sandstone/mudstone (F₈) and channeldeposits facies (F₉).