Abstract:

Three problems are discussed in this paper. (1) Superimposed types of extensional fault depressions at different epochs. According to modes of superimposition, the types of superimposed fault depression can be classified as follows: isolate, inherited and interference types. Based on interference relationship between early and late fault depressions, the interference types can be subdivided further into three subtypes: synthetic, convergent and intersecting interference. (2) Formation mechanism of these interference types is controlled by following factors. The synthetic and convergent interference types are related with arrangement of synthetic and convergent preexistent basement faults and longitudinal or transverse migration of fault activity, whereas the intersecting interference type is related with rotation of extensional direction with time. (3) Hydrocarbon occurrence is related with various superimposed types of the fault depressions. Some types, such as inherited and convergent interference type are in favor of generation and preservation of oil and gas, whereas synthetic and intersecting interference type played a destructive role in general, because early depression was partly uplifted and modified by development of late depression.

Key words: superimposed type of fault depression, type of inherited superimposition, type of interference superimposition