Abstract: Similarity factors are calculated from both field observations and remote sensing image interpretations for analyzing tectonic similarities between the Fenwei and Balkal rift systems in 7 different aspects by means of statistic methods on the basis of abundant geologic and geophysic data. The similarity factor is 0.999 for their geometry, 0.923 for the sedimentation rate at various stages of rifting, 0.635 for the total subsidence in the Cenozoic, 0.794 for fault activities during rifting, 0.813 for seismic activities and 0.766 for the shape of the Moho(between Fenwei and Balkal rift systems). Further statistic check (student-t check)shows that there is remarkable similarity between the two in 3-demensional structure framework, and historical and present activities.
An analysis of the results obtained from GPS survey and stress measurements suggests that the high similarity between the Fenwei and Balkal rift systems may be dynamically related to the large scale S-shaped extension originating from the unequal westward motion of the two N-S oriented adjoining terrains in the east Asian continent.