Abstract：In order to study tectonic characteristics of early Cretaceous and age of the Hanzhuang Formation in Jiyuan basin, ground fissures and associated water escape structures are observed in sandy gravel bed at the bottom of the lower Cretaceous Hanzhuang formation, Jiyuan basin. The ground fissures are “V”shaped in groups and filled with medium fine sandstone and a small amount of fine gravel. The water escape structures are net appearance in the bedding surface. According to morphological characteristics of the ground fissures and the deformation process of sandy gravel bed, the ground fissures were formed in a process of continuous and rapid accumulation. It reflected a strong tectonic activity with the uplift and extension of the earth's crust. They are regarded as the ancient seismic activity. The ground fissures in the Hanzhuang Formation were response to the uplift of Taihang mountainin the early Cretaceous, and provided evidence to the Hanzhuang formation formed in the early cretaceous.

Keyword：Jiyuan basin;Hanzhuang formation;early Cretaceous;ground fissures;Taihang uplift;