挤压区局部构造转换带类型及石油地质意义

构造转换带在逆冲断裂带中具有调节主干逆冲断层之间位移的作用。根据相邻主干逆冲断层在剖面上的组合关系并结合塔里木盆地中央隆起区的研究成果,将挤压区构造转换带分为相向倾斜、背向倾斜和同向倾斜型3类。相向倾斜型在转换带部位发育背冲断块样式,背向倾斜型通过逆冲三角带实现逆冲断层的倾向转换,同向倾斜型通过叠瓦构造实现断层位移的转换。分析了影响构造转换带形成的因素,认为基底构造、滑脱层、沉积相与岩性差异以及应力作用方式等对转换带形成具有重要影响。构造转换带是构造变形相对复杂的区带,不仅控制着富有机质沉积物的分布,形成有利的油气聚集区带,而且密集的断裂系也为烃类的运移提供了通道,并且有利于发育与断层、背斜有关的各种构造圈闭。

Types of Structural Transfer Zone in Compressional Area and Its Significance of Petroleum Geology

Structural transfer zone is a significant geologic structure which regulates the displacement of major thrust faults in thrust belt.According to the geometric relationship of adjacent major faults in cross section with a case study in central uplift,Tarim basin,the structural transfer zone in compressional area can be classified into convergent,divergent and synthetic assemble patterns.Convergent assemble pattern develops pop-up structural style in transfer zone;transfer zone of divergent assemble pattern develops triangle zone;synthetic assemble pattern transfers its displacement by imbricate fault.The possible styles of thrust fault linkage in transfer zone were discussed.The main factors that control the formation of the structural transfer zones were analyzed which are related to the substrate characters,detachment surface,difference in sedimentary facies and lithology,and stress patterns and so on.Structural transfer zone,which is relatively a complicatedly deformed area,not only becomes an important play for hydrocarbon accumulation owing to its control of euxinic sediments distribution,but also provides pathways for hydrocarbons migration because of closely spaced faults.Moreover,all kinds of structural traps related to fault and anticline potentially developed in structural transfer zone.