陆内裂陷盆地的复式断陷结构类型及其油气地质意义:以海-塔盆地早白垩世盆地为例

陆内裂陷盆地通常发育大量地堑、半地堑,盆地结构和构造样式受盆地内部地堑、半地堑的叠加与复合方式的影响。文中将由多条断层、不同期次的断层共同控制的断陷称为"复式断陷"。依据同一时期断陷复合构成的盆地结构可以将复式断陷划分为串联式、并联式、斜列式和交织式等4种复合型式,依据不同时期断陷叠加构成的盆地样式可以划分为继承型、利用型、新生型3种叠加类型。海-塔盆地在早白垩世最初是发育大量相对分隔的小型地堑、半地堑,随着地壳渐进的伸展构造变形,多个同期小型半地堑复合在一起形成相对大的断陷(相当于铜钵庙组沉积期)。在早白垩世中期(相当于南屯组沉积期),新发育的断陷叠置在早先发育的断陷之上,最终形成了盆地中的17个区域规模的复式断陷。海-塔盆地早白垩世的断陷复合和叠加过程直接影响沉积盆地的油气成藏条件。并联式、交织式复合和继承型、利用型叠合形成的复式断陷有利于优质烃源岩的发育,断陷复合过程中的构造变换带有利于优质储集层的发育,长期活动的基底断裂及相关构造带有利于形成含油气构造带。

Styles of complex faulted sags in rifting basin and its significance for petroleum geology: An example from Hailar-Tamsag Early Cretaceous Basin

Rifting basin is usually developed of grabens and/or half-grabens,so that the basin configuration and structural styles are distinctly impressed by different patterns of composition and superimposition.This paper named the sag controlled by multi-pieces and multi-periods of normal faults as "complex faulted sag".By the configuration of basin compounded by contemporaneous faulted sag,the "complex faulted sags" in the Halaer-Tamsag Basin could be categorized into 4 types of composition models which are named respectively as serial,parallel,diagonal and interlaced,and by the superposed style of sequel basin,"complex faulted sags" could be divided into 3 types of superimposition models which are named respectively as inherited,imposed and neonatal.Halaer-Tamsag Basin develops large quantities of relatively separate mini-faulted sags in the early stage of Early Cretaceous,but the synchronous mini-sags was compositing into larger faulted sag along with the progressive crustal extension.Halaer-Tamsag Basin develops some of relatively separate large sags in the middle of Early Cretaceous,and they superposed upon the pre-existing faulted sag in different patterns.The newly developed faulted sags superimposed upon the previously formed sags and finally there are 17 complex faulted sags developed.The processes of compositing and superposing of complex faulted sags during Early Cretaceous in Hailar-Tamsag Basin directly effect the conditions of oil accumulation in the sedimentary basin.The composition in parallel,diagonal and interlaced patterns and the superposition in inherited,imposed styles,are in favor of the development of high quality hydrocarbon source sequence.The transfer zones in the process of structural compositioning are in favor of the development of high quality reservoir.The basement involved fault zone and related structures are in favor of developing petroliferous structure zone.