临汾盆地地壳精细结构和构造——地震反射剖面结果

Fine crustal structure and tectonics of Linfen Basin——from the results of seismic reflection profile

采用深、浅地震反射相结合的探测方法，对临汾盆地的地壳结构和隐伏活动断裂进行了研究．结果表明，研究区地壳具有清晰的上、中、下地壳结构特征，其地壳厚度约为38～42km．临汾盆地为典型的半地堑沉积盆地，盆地沉积层最深处约为5～6km．莫霍面在临汾盆地下方出现约3km的上隆，其展布形态与盆地基底呈“镜像”对应关系，显示出临汾盆地为拉张作用下的纯剪切盆地模式．深地震反射剖面揭示的一系列铲状或面状正断层在剖面上表现为“负花状”构造特征，其中，罗云山山前断裂和浮山断裂为临汾盆地的东、西边界控制断裂，具有规模大、切割深度深和多期活动的特点，对临汾盆地的形成、地层沉积和褶皱以及地震活动都有重要的控制作用．研究结果为深入理解该区的深部动力学过程、分析研究深浅构造关系、评价断裂的活动性提供了依据．

We used a method combining deep and shallow seismic reflection to explore the crustal fine structure and buried active faults of the Linfen basin. The results show that the crust of the study area is characterized by a distinct structure of upper, middle, and lower crust, and the crustal thickness is about 38-42 kin. Linfen basin is a typical half-graben sedimentary basin, and its deepest sedimentary layer reaches 5 - 6 km. The Moho interface is uplifted about 3 km beneath the Linfen basin, and its morphology has an apparent mirror image relationship with the basin basement, showing the Linfen basin as a pure-shear basin under the tension force. A series of listric or plane normal faults revealed by deep seismic reflection profile appears as a ＂negative flower-shaped＂ structure. Among them, the frontal fault of Luoyunshan and Fushan fault control the western and eastern boundary of the Linfen basin, both of which possess the characteristics of large scale, large penetration depth and multi-period tectonic activities, which play the important role in controlling the Linfen basin formation, sedimentary strata, folding and earthquake activity in the study area. The results provide the evidence for intensively understanding the deep dynamic processes, further research of the relationship between shallow and deep tectonics, and assessment of fault activity.