Abstract:

Biyang Depression is a typical continental fault-depressed lacustrine basin. The Eh₃ member in the depression is in the A～B substages of late diagenesis, the cementation and solution of the diagensis bear close relation with the formation of diagenetic traps. Carbonate is the main cement; deep burial solution in the late diagenetic stage is the major solution types. The existence of shielding bed is the key factor of forming the diagenetic traps. According to their characteristics, the diagenetic traps could he divided into three types such as the traps relating to lithologic pinch out, fault and lenticular types. These traps could be further divided into 9 subtypes. The factors that effected the formation of the traps include sedimentary facies, diagenesis, the features of fluid, solution, faulting and expulsive pressure. Among them, sedimentary facies, diagencsis and the feature of fluid are the main factors.

Key words: fault-depressed lacustrine basin, Biyang Depression, diagenesis, cementation-shielding, diagenetic trap, genesis