Abstract:

Reversed faults and folds are well developed in Gas faulted depression. The faults, closely accompanying the folds, are located on one side or both sides of anticlines and the highs of each structural layer superimpose vertically. Most faults have obvious control over sedimentation. The regional NWW contemporaneous reversed faults in Gas faulted depression would have controlled the distribution and scope of local sedimentary sags (oil generating sags), the depocenters of which are located near the downthrow blocks; while the relatively small contemporaneous reversed faults are mainly developed within sags or swells and would have controlled the formation and development of local structural traps. The faults and anticlines were not developed at the same time. The faults were formed earlier on the basement as synsedimentary faults, which thrusted while depositing. The anticlines were formed later as a result of compressional or compresso torsional structural stress in Late Tertiary. Anticlinal structures did not show synsedimentary characteristics of thin and coarse on the crest, and thick and fine on the limb until the early Miocene.

Key words: Gas faulted depression, basement involvement pattern, contemporaneous reversed fault, anticlinal structure, growth index, synsedimentation