Abstract: As one of the rhombic blocks in North China, Kaifeng depression is on the south of the northern Huabei depression and in the north of the southern Huabei depression, bounded by Xinxiang-Shangqiu Fault and Zhengzhou-Kaifeng Fault, respectively. So far, the activity of Zhengzhou-Kaifeng Fault during Kainozoic era and the relationship between Zhengzhou-Kaifeng Fault and Xinxiang-Shangqiu Fault is still unknown. We interpreted several deep seismic profiles across Taikang uplift and Kaifeng depression on the basis of the strata sequence exposed by the 8 drill holes in the related area. The outcomes indicate that the Zhengzhou-Kaifeng Fault strikes EW on the whole, presenting undulating feature in plain, with a length about 154km. The profiles show the dip angle of the fault is steeper in the shallow than that in the deep, with an obvious "L-shaped" turning point. In Paleogene, the fault was a normal fault. In its hanging wall, the Kaifeng depression, there deposited hundreds of meters of Eogene. After middle Himalayan movement, Zhengzhou-Kaifeng Fault converted to a strike-slip fault, the dip angle became steeper, but the activity became weaker. The Zhengzhou-Kaifeng Fault ended its activity before Quaternary. As a response to the compression in the footwall caused by the sustained sinistral shearing, there developed a series of NW-trending, en echelon wide and gentle folds. Then, the activity in Kaifeng depression shifted to its north boundary.

Key words: Taikang uplift, Kaifeng depression, Zhengzhou-Kaifeng Fault, Xinxiang-Shangqiu Fault, middle Himalayan movement

摘要： 开封凹陷向北以新乡-商丘断裂为界，与北华北坳陷相邻，向南以郑州-开封断裂为界与太康隆起相接，是由多组断裂围限的菱形块体。目前关于郑州-开封断裂的新生代活动特征及其与新乡-商丘断裂的构造关系仍不甚明确。通过对开封凹陷及太康隆起内的8口探井揭露的地层进行细分对比、标定地震地质层位，完成了多条地震反射剖面的对比解释。最终发现郑州-开封断裂平面上具有波状起伏特点，总体走向近EW，延伸长度约154km。剖面上该断裂呈上陡下缓、具有明显转折点的"L"型断层；转折点位于古近系与新近系不整合接触面附近。该断裂古近纪时期为强活动正断层，造成北侧开封凹陷内巨厚的古近系沉积。中喜马拉雅运动后该断裂向水平扭动演变，倾角变陡的同时活动程度急剧减弱，至第四纪已停止活动。郑州-开封断裂南侧部分段产生NW向雁列状宽缓褶皱带，以地壳缩短的方式响应了缘于断裂左旋剪切活动所产生的挤压效应。开封凹陷的活动性向北转移。

关键词: 太康隆起, 开封凹陷, 郑州-开封断裂, 新乡-商丘断裂, 中喜马拉雅运动