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??о???????????????????????????????????????μ?????????????????????????????????550 m×875 m????????????????????????????????????????????????????????????????N20°??22°E????????????и???????????????F₁????SE???ζ???F₂????NW?????????????????F₁????????ζ???F₂?￡???????ζ???F₂???F₁?????????????????????????????????????????????????????F??1??F??2??????????????????????????????????????????????????????С??????????780??800 mF₂????鲢??F₁???????

THREE DIMENSION STRUCTURE OF LUHUATAI FAULT

In order to investigate geometry shape and activity of Luhuatai Fault Zone which locates in the northwest Yinchuan Basin??a 3D seismic exploration was completed whin an area of 550 m×875 m.The results show that it is a buried active fault zone and consisted of two faults??main fault F??1 and secondary fault F??2.The fault zone moved untill the late stage of Middle Pleistocene. Trend of F??1 is SE??and F??2 is NW??both of them are normal faults. The activity time of F??1 is newer than that of F??2??and the fault throw of F??1 is larger than that of F??2. The buried deepth of the up??breakpoint of F??1 has a trend of increasing from North to South. The distance between F??1 and F??2 increases gradually from North to South on the horisontal plane??reduces gradually with depth increase on the vertical profile??and F??2 merges into F??1 at the depth of about
780-800 m.