层序界面在预测樊东地区岩性圈闭中的作用

Effects of stratigraphy sequential interface in prediction of lithologic traps in Fandong area.

层序地层分析中,层序界面的识别及界面性质的确定最为关键。在陆相盆地中,层序界面通常形成于基准面下降与上升的转换位置,也是盆地发育过程中可容纳空间和沉积物补给比值最小的位置。该时期物源补给充分,砂体发育,砂体成因类型和展布样式在界面附近发生变化,因而不同砂体成藏条件、成藏类型也显著不同。本文针对东营凹陷樊东地区下第三系沙三段中亚段发育的数十米厚的砂岩,用可容纳空间和沉积物补给比值法确定其层序界面,认为此层序界面之下发育三角洲前缘滑塌浊积砂体,层序界面之上发育浊流成因的盆底扇砂体及重力流—牵引流成因的斜坡扇砂体。

University of Geologic Science,100083,China Abstract: In sequence stratigraphic analysis,the identification of stratigraphy sequential interfaces and definition of the nature of interfaces are more important.In continental basin,the sequential interface are usually formed in transitional position between rising and falling of datum,that is the position of minimum ratio between capable space and sedimentary supply.In that period,the source supply was abundant,sand body was development and the causes of forming sand body and distribution of sand body are changed around the interfaces,so that the accumulation conditions and types of different sandy bodies are very different.Faced with more than tens meters of sand rock developed in Paleogene S3 Zmiddle Segment in Fandong area,Dongying depression,the sequential interface is determined by using the ratio between capable space and sedimentary supply,it's considered that delta front slum turbidite sand bodies are developed under the interface,above the interface,the basin floor fan sand bodies caused by turbidite current and slope fan sand bodies caused by gravity flow traction current are developed.