华北南部地区古生界构造演化及其油气远景

Structural Evolution and Hydrocarbon Prospects of Paleozoic in Southern Part of North China

华北南部地区的地质演化与华北其他地区一样,经历了结晶基底形成、中—晚元古代台内裂谷发育、古生代稳定地台沉积和中—新生代地台活化等发展过程。但本区受秦岭褶皱带构造活动的强烈影响,因而具有相对独特的构造演化特征和油气控制条件。早寒武世中期,古秦岭海槽伸展扩张,沉积了一套全区广泛分布的以碳酸盐岩为主夹泥页岩的地层;晚寒武世开始,古秦岭海槽向北俯冲挤压,在本区南部出现一个平行于海槽的大陆边缘隆起;中奥陶世发生三次较大规模的海进—海退,边缘隆起继续存在,区内水体相对封闭,形成膏盐沉积;中奥陶世末,古秦岭海槽回返,且边缘隆起长期存在,使本区南部遭受剥蚀特别强烈,致奥陶系甚至部分寒武系地层缺失。中—新生代,古生界地层受到强烈改造。现今古生界主要残存于鲁山—周口—阜阳—淮南—线以北地区,下古生界残厚约1000m,上古生界残厚约400m～800m。综合评价认为,本区古生界含油气远景最有利地区为襄城—汝南地区,次为济源地区和商丘—黄口地区。

As the region is strongly influenced by orogenic movement of Qinling folded belt, it has a distinctive structural evolution characteristics and petroleum geological conditions different from that in the other parts of North China. In the middle of Early Cambrian, owing to Pale- o-Qinling trough stretching, a set of carbonate sequence intercalat- ed with shale was deposited and regionally distributed. From Later Cambrian, the trough subducted and compressed towards the north, a continental marginal uplift parallel to the trough appeared in the southern part of the region. Three progression---regression on a large scale had happened in the Middle Ordovician, but the marginal uplift was still existed so as to result in gypsum deposit because of the sealed drainage. In the end of Middle Ordovician, since the Qinling trough inverted and the marginal uplift had continu- ously existed for a long time, it made the sequences be strongly de- nuded and short of Ordovician and even part of Cambrian in the southern part of this region. In Meso-Cenozoic, the Paleozoic se- quences were severely reformed. So far the dominant remnants of Paleozoic are distributed to the north of Lushan-Zhoukou-Fuyang- Huainan. The remnant thickness of Lower and Upper Paleozoic are about 1000m and 400--800m separately. It is considered based on comprehensive evaluation that the most favorable areas for Paleo- zoic hydrocarbon potential are first in Xiangcheng-Runan, second in Jiyuan and Shangqiu-Huangkou.