根据孢粉资料确定伏尔加地区弗拉阶和法门阶界线

俄罗斯伏尔加格勒伏尔加地区上泥盆统弗拉阶和法门阶的界线以3种剖面类型为代表。第一种类型的界线剖面广泛分布于俄罗斯地台,但两阶之间有沉积间断。第二种类型剖面地层发育较完整,即Volgogradian层直覆于Livendian层之上。前者以Corbulispora viminea-Geminospora vasjamica孢子组合带为特征。第三种类型剖面存在于前里海(Pre-Caspian)凹陷的西侧,是最近根据孢粉资料确定的;地层剖面不完整,在中弗拉阶的Semilukian层有剥蚀面,上覆以不同时代的(弗拉期或法门期)盖层。

THE FRASNIAN-FAMENNIAN BOUNDARY IN THE VOLGOGRAD VOLGA REGION BY PALYNOLOGICAL DATA

The boundary between Frasnian and Famennian stages in the Volgograd Volga region is represented by threesection types. The first type of these boundary sections is widely spread on the Russian Platform in the areas with a break insedimentation occuring between Frasnian and Famennian stages, i.e. between the Livenian horizon of the Frasnian stage andthe Zadonian horizon of the Famennian stage. The second type is represented by more complete sections with the Volgogradianhorizon overlying the Livenian one. The Volgogradian horizon is represented by Corbulispora viminea - Geminospora vasjamicapalynozone. The third type has been recently identified by palynological data in the western flange of the Pre-Caspian depression(Mantsourova, 2000a). It is represented by incomplete stratigraphic sections with the erosive surface of the Semilukian horizonof the Middle Frasnian substage overlapped by the structures of various ages: the Evlanov-Livenian sediments of the Frasnianstage or Volgogradian sediments of the Famennian stage.