The geometric simulation and analysis of the blind growth fold in the overthrust belt of the southern section of the frontier Longmen Mt. during Late Triassic

The seismic profiles processed by high-resolution display that a blind growth fault-bend fold emerges in depth of seismic exploration area in Dayi in the southern section of the frontier Longmen Mt. This paper presents a detailed structural interpretation to seismic section, then describes the deformed geometry related to the pre-growth strata, the growth strata and the post-growth strata on both limbs of the fold. The computer geometric simulation, based on the model of fault-bend fold, is utilized to stimulate the geometry of the blind growth fold at different sedimentation rates in Dayi. These structural features are subsequently extracted and compared with the actual seismic reflection section. Our research suggests that a low angle overthrust formed during Late Triassic also appears in the southern section of the frontier Longmen Mt. overthrust belt. The event of structure took place at the depositional stage of a portion of the middle and upper fourth member of Xujiahe Formation (T(3) x (4)), which corresponds to thrusting in the northern section of the frontier Longmen Mt. However, the thrusting displacement here is smaller than one of the northern section.