张扭断裂带内复合花状构造的成因与意义

花状构造是走滑断裂带内的标志性构造变形，传统上按照内部构造样式的差异可分为正花状构造和负花状构造。油气勘探揭示，在渤海海域新生代的郯庐断裂张扭变形带内，除发育正花状构造和负花状构造外还发育一种特殊的花状构造，即以背斜和正断层组合为典型特征的复合花状构造。通过分析复合花状构造的特征和形成机理认为，复合花状构造发育于张扭变形带中断层受阻弯曲或受阻叠置部位，具有走滑、挤压和伸展3类应变共存以及挤压变形和伸展变形同时发生的特征。复合花状构造可看作是张扭变形带内的典型变形样式，是伸展、挤压和走滑应变在局部挤压环境下复合变形的产物，其形成的应力状态处于正花状构造到负花状构造的过渡状态。复合花状构造因其特殊的构造样式和形成背景有利于油气的聚集成藏。

Genesis and significance of hybrid flower structure in a transtensional fault zone

Flower structures are the typical products of tectonic deformation in strike-slip fault zones. In conventional studies, flower structures can be divided into two types based on the differences in their internal structural architecture, i.e., negative and positive flower structure. The oil-gas exploration reveals that besides the above two types of flower structure, a special flower structure is developed in the transtensional deformed zone of the Cenozoic Tan-Lu fault in the Bohai Sea, i.e., a hybrid flower structure characterized with the assemblage of anticline and normal fault. Through analyzing the characteristics and formation mechanism of hybrid flower structure, the results indicate that it is developed in the fault restraining bend under transtensional deformation, presenting the co-existence of strike-slip, compression and extension as well as the synchronization of compressional and extensional deformation. The hybrid flower structure can be considered as a typical and complex deformation pattern, as the result of extension, compression and strike-slip under the local compressional environment, and its stress state is during the transition stage from the negative to positive flower structure. With special tectonic pattern and setting, the hybrid flower structure is favorable to hydrocarbon accumulation.