Abstract:

Complex half-graben structures developed in the Paleogene hanging wall along Lanliao fault in Dongpu sag. Dongpu sag, which forms plenty of north-northeast basement faults, has a structural architecture with east-west zonation and south-north subsection. There are two regional transfer zones, which extend from east to west along Baimiao-Nanhejia and Maogang-Liutun respectively, and partition the Tertiary extensional fault-sag into south, middle and north districts. Each district has different features in structural styles, depositional configuration and hydrocarbon accumulation. During the complicated tectonic history, not only the clastic rocks, but also the salt rocks have taken part into deformation in Dongpu sag; the tectonic stress-field is mainly extensional at earlier stage and is superposed by wrench stress later. Therefore, four structural styles, such as extensional faulted structures, transform structures, extensional fold structures and salt structures, accompanied with strike-slip structures have developed in such a tectonic setting, which comprised the main structural types of Dongpu sag characterized by rift basin.

Key words: Dongpu sag, structural style, Lanliao fault, basement formal fault, salt structure