“花窗结构,菱形中心”——断陷盆地的沉积规律

FENESTRAL STRUCTURE,RHOMBIC CENTER"-DEPOSITIONAL REGULARITY OF FAULTED BASINS

刘秋生 李火车 何碧竹 张玉体 王亚红 王婧韫 姜小林

Liu Qiusheng Li Huoche He Bizhu Zhang Yuti Wang Yahong Wang Jingyun Jiang Xiaolin

陆相断陷盆地具有特定的沉积环境.无论是箕状式、地堑式,还是它们之间的组合--混合式,在剖面形态、沉积分布均具有明显的共性.剖面形态上,这些断陷不是三角形就是倒梯形,即所谓的"花窗结构".无论那一类断陷盆地均具有明显的深坳部位,在深坳处沉积物较细,向两侧逐渐变粗.由于盆地演化具周期性,在一个完整的水进-水退旋回中,中间细两侧粗的分界线是两条折线,两条折线结合在一起构成菱形,即所谓"菱形中心".由于盆地演化具有多期性、复杂性,菱形中心可以呈串出现,菱形形态可能有较大的变化.对断陷盆地而言,油气勘探的关键是源岩,而"菱形中心"正是断陷盆地主要的源岩区.

Continental faulted basins formed in specific depositional environment. No matter they are dust pan,half graben and complex types, they have distinct general characters in section configuration and the distribution of sediments.In section configuration, the depressions are either triangle or reversed trapezoid-fenestral structure.Every type of faulted basin possesses clear deep depressed center with fine grained sediments and the sediments around the center get coarse. In a complete ingression regression cycle,the boundary lines between fine grain sediments and coarse grain sediments are two polygons appeared as a rhomb,that is the "rhombic centre". The rhombic centres may occure in bunches,and their shapes may be variety.The rhombic centres are the main source rock areas of the faulted basins.

10.11743/ogg20010305