贝尔凹陷苏德尔特构造带的形成与演化

苏德尔特构造带是海拉尔盆地贝尔凹陷的重要油气聚集带之一。使用平衡剖面技术和基于斜向剪切模型的人字形桁架法对苏德尔特构造带及其两侧的贝西断陷和贝中断陷进行了详细的构造几何学和运动学解析,认为在南屯期近SN向伸展,形成近EW向断陷盆地群之后,又叠加了大磨拐河组早期的短时间NW向伸展,以及此后的坳陷沉降,才形成了苏德尔特构造带特殊的构造样式。贝中断陷的东侧边界断层是整个贝尔凹陷在大磨拐河组早期伸展的主干边界断层,并且断层面具有坡坪式特征。苏德尔特构造带是发育于第一阶断坪上部的"滚动背斜",是重力和边界断层几何形态共同控制的结果,形成机制属于重力影响下的横弯褶皱作用,而非侧向挤压引起的纵弯褶皱作用。

The formation and evolution of Sudeerte tectonic belt in Beier depression

The Sudeerte tectonic belt is one of the most important hydrocarbon accumulations in Beier depression of Hailar basin. From the detailed structural geometry and kinematics analysis of Sudeerte tectonic belt and peripheral Beixi subdepression and Beizhong subdepression using balanced section technique and herringbone truss method based on inclined shear model, the authors detected that the special structure style was caused by a series of extensions:the direction of extension in Nantun Formation was nearly NW-striking, forming an EW-trending rift basin group, then the direction changed to northwest in a short period of early Damoguaihe Formation stretching and continued thermal depression to the present. The boundary faults in the east of Beizhong subdepression were the major boundary faults of Beier depression in the extension of early Damoguaihe Formation, and show a ramp-flat listric feature. Sudeerte tectonic belt is "roll-over anticline" formed in the upper part of the first fault floor due to the combined effect of gravity and geometry of boundary fault. It is thus held that the mechanism of anticline type of Sudeerte tectonic belt is bending fold rather than buckle fold.