黄骅坳陷缓坡带沙河街组物源体系分析

Provenance system of Paleogene Shahejie Formation in the gentle slope(ramp) of the Huanghua depression in Bohai Gulf,China

黄骅坳陷缓坡带位于埕宁隆起和黄骅坳陷的过渡地区,地形坡度较小,显示为埋藏型低角度缓坡带。根据砾石成分、砂岩成分、重矿物、砂体分散体系和沟-谷体系分析的研究成果,对缓坡带的次级古物源口及古水系进行分解,将其从西到东分为西部物源口、中部物源口和东部物源口。它们呈东西向线状分布于埕宁隆起的北侧缓坡带,古水系的轴向垂直于主要构造线,具有线状物源的特点。此外,在该缓坡带上所发育的3条古水系以短轴的横向水系为特征,水系走向呈近南北向,垂直于主要构造线。研究结果表明,3个次级物源口和古水系不仅控制了缓坡带上砾石成分、砂岩成分、重矿物组合在东西方向的分区和变化,同时多级断阶也控制了砂体分散体系和沟-谷体系在南北方向上的空间展布形态。

The gentle slope （ramp） of the Huanghua depression is a buried slope landform and located on the north slope of the Chengning uplift in the southeast of the Huanghua depression. It can be divided into three tectonic-geomorphologic units from south to north, that is, the outer belt, middle belt and inner belt. By the components of gravel and sandstone, heavy minerals and sandstone bodies dispersion system, the paleo-provenances and paleo-river systems on this slope are established. There are three paleo-provenances and paleo-river systems on the northern gentle slope （ramp） of the Huanghua depression, which are divided into the western, middle and eastern paleo-river system （corresponding to the three paleo-provenances） from west to east. The paleo-river system shows as a branch-river and its strike is vertical to the main tectonic line of the slope. The three paleo- provenances and paleo-river systems control the change of the components of gravel and sandstone, heavy minerals and sandstone bodies dispersion system from west to east on the northern gentle slope （ramp） of the Huanghua depression. Finally the characteristics of the paleo-provenances and paleo- river framework on the ramp of the Huanghua depression are summarized in this paper.