伸展盆地区断裂构造特征与成因

近十年来断裂构造研究进展迅速,研究思路发生了重大转变,强调应变与应力在断裂形成过程中的同等重要性。重点论述了断裂位移特征及影响因素,断裂位移在断层中部最大,端部最小至零,具有与断层规模无关的特征,但它受断裂分段、连接、近端过程等影响而发生变化。位移作为应变的结果,控制着横向褶皱的形成和分布、沉积中心的迁移(断裂单侧扩展时)或沉积位置不变但范围扩大(断裂双侧扩展时)以及沉积充填结构等。探讨了断裂三维几何形态分类及断裂形成与形态的控制因素：深部与浅部耦合(基底构造的活化与沉积盖层的响应),建造与改造的耦合,边界条件与构造应力场,沉积压实和埋藏作用等。提出了断裂分级和组合规律,总体上伸展区断裂可分五级,一级控盆,二级控坳,三级控带,四级控圈,五级复杂化;不同级别的断裂三维组合规律可分为软连接组合和硬连接组合。伸展区断裂生长史可划分为成核、扩展、释压、连接、消亡和活化6个阶段。

Features and genesis of faults in extensional basins

Research of fault has made much progress in recent decade, especially the strain and stress are regarded to have the same role in the process of faulting. Displacement features of faults and their affective factors are described in the paper. It is concluded that the displacement has nothing to do with the scale of faults but generally depends on fault segmentation, linkage, near-tip process and other parameters. The largest displacement occurs in the central part of faults with no displacement at the two tips. As a result of strain, displacement controls forming and distribution of transverse fold, migration of depocenter under the condition of one-way lateral propagation or enlargement of sedimentary range under the two-way lateral propagation as well as change of filling style of sediments. Discussed contents also include the 3-D geometric classification and its controlling factors, coupling or response of surface sedimentation to deep process (reactivation of the basement), coupling of formation and reformation, boundary condition and the stress field, impaction and filling interaction between the horizontal and vertical movements as well as fault assemblage and classification. Faults in extensional area can be divided into five classes in scale, they control respectively formation of basin, depression, structural belt,the trap and complex array of normal faults. Various scale faults can be divided into soft linkage and hard linkage assemblage. The process of fault growth is subdivided into six stages, named as nuleation, propagation, releasing, linkage, termination and reactivation.