裂陷盆地中的构造变换带及其石油地质意义

Structural Transfer Zones and Significance for Hydrocarbon Accumulation in Rifting Basins

构造变换带是裂陷盆地中的重要构造变形。讨论了构造变换带的含义、类型及对油气聚集的意义。裂陷盆地主干正断层之间的几何关系可以分为同向倾斜、背向倾斜和相向倾斜共3种组合方式;正断层之间的构造变换方式可以分为缓冲式、接力式、消长式、传递式和消减式等5种形式,构成15种类型的构造变换带。不同方式的断裂组合所形成的不同构造变换带类型会随着主干正断层位移的渐进增大发生相应的转变。构造变换带是有利的油气聚集区带:(1)它常常是主边界断裂带上地形高差变化较小的部位,是主要碎屑物源注入裂陷盆地的入口处,有利于发育储集层;(2)长期处于盆地内部相对高的构造部位,而且近邻生油凹陷,是油气运移指向区带;(3)它是裂陷盆地构造变形相对复杂的区带,有利于发育多种样式的油气圈闭。

Transfer zones, including transfer faults, are important results of structural deformation in rifting basins. It is discussed to the meanings, types or styles of transfer zones and the significance for hydrocarbon accumulation. Responding to the geometry and kinematics of major normal faults, the transfer zones could be different styles in rifting. In geometry, major normal faults include synthetic, divergent and convergent assemble patterns. In kinematics, the transfer actions between the normal faults could be divided into 5 basic styles： glacis （or approaching）, relay （or overlapping）, swing, pass （or transferring） and fade-away （or ending）. Causes lead to the transfer zones become important play for hydrocarbon accumulation in rifling basin. First, the transfer zones could lower the relief in hypsography along the boundary faults zone so that they are commonly sites of major clastic input rifting basin. Secondly, the transfer zones are relative high in the basin and border on the source sag so that the paths of hydrocarbon migration always point to the transfer zones during the evolution of rifting basins. Third, the complicated deformation in transfer zones was favorable to develop various styles of structural traps in the rifting basins.