重庆綦江老瀛山地区槽模构造的发现及古流向意义

The Discovery of Flute Casts and Their Paleocurrent Directions in Laoyingshan Region in Qijiang District,Chongqing,China

在对重庆綦江老瀛山地区的野外考察中,在上白垩统夹关组地层发现3处沉积岩底面上成群分布的槽模构造,分布海拔为766~891m,岩性为长石石英砂岩,下伏岩层均为泥岩或泥质粉砂岩.槽模长轴彼此平行,呈雁行状排列,轴长在5~20cm,槽模突起陡端指向25°~37°方向,表明晚白垩世老瀛山地区的古水流自NE向SW流动.这些槽模的发现,为恢复晚白垩世綦江地区古流水的方向提供了直接的证据.

In an investigation of fieldworks in Laoyingshan region in Qijiang District,Chongqing,three groups of flute casts were discovered in Upper Cretacious Jiaguan Formation.They were found to be distributed at the bottom of the sedimentary rock with an elevation of 766-891 ma.s.l..The stratum developing flute casts consists of feldspar-quartz sandstone,with an underlying layer of mudstone or argillaceous siltstone.The long axis of these flute casts paralleled each other like an echelon arrangement,with a length varying from 5 to 20 cm,and the directions of their steep and bulge parts were 25-37°,indicating that the paleocurrent directions were generally from northeast to southwest in Laoyingshan region in the period of late Cretaceous.The discovery of these flute casts provides a direct evidence for recovery of paleocurrent direction in Laoyingshan region.