岐口凹陷新近系生物-遗迹相及环境解释

Biofacies and Ichnofacies of Neogene in the Qikou Depression and Their Environmental Interpretation

岐口凹陷新近系包括明化镇组和馆陶组.通过新近系中的孢粉、介形虫和遗迹组构的系统研究,识别出孢粉53个属种,并建立了两个孢粉组合,分别为Magnastites(粗肋孢)-Ulmus(榆粉)-Taxodiaceaepollenites(杉粉)组合和Polygonaceae-Chenopodiaceae组合;发现介形虫12个属种,介形类以金星介科分子为主,少数湖花介科分子,以壳形单一、壳壁薄、表面光滑的类型为主,表现了典型的非海相淡水介形类面貌;划分出4种遗迹组构类型,分别为Scoyenia遗迹组构、Skolithos遗迹组构、Palaeophycus遗迹组构和强扰动组构.在此基础上,探索了生物与环境的关系,划分了A、B、C、D、E5种生物-遗迹相带,分别代表泛滥平原、蓄水注地或泛滥平原小型湖、河道及水下分流河道边部、滨浅湖和前三角洲沉积环境.

Sporopollen, ostracod and ichnofabric characteristics of Neogene in the Qikou depression were studied and fifty-three genus were recognized. Two sporopollen combination, .Magnastites-Ulmus-Taxodiaceaepollemites and Polygonaceae-Chenopodiaceae, were established. Twelve genus ostracod were identified. The ostracod shell is singleness, thin and slippy, which exhibites the visage of typical freshwater ostracod. Four ichnofahric were identified, which are Scoyenia ichnofabric, Skolithos ichnofabric, Palaeophycus ichnofabric and acute disturb ichnofabric respectively. Based on the above research, five biofacies and ichnofacies were carved up, which represent overflow plain, small lake in the overflow plain, interchannel or subaqueous spreader interchanneh shallow lake and predeha sedimentary environments respectively.