南华北石炭—二叠系陆表海层序古地理演化

Sequence Paleogeographical Evolution of Epicontinental Deposit of Permo-Carboniferous in Southern North China

通过对野外露头和钻孔的沉积相、古生物以及准层序堆叠方式的对比分析,将南华北石炭—二叠系陆表海沉积划分为三个三级层序：Sq1～Sq3。以层序和最大海泛面为绘图单元,分别对各层序进行了古地理重建。研究发现Sq1时期海侵范围小,时间短,来自东北方向;Sq2时期海侵范围达到最大,海侵方向由东北变为东南;Sq3时期延续了Sq2时期的古地理格局,但沉积中心向南迁移,盆地物源均主要来自北方。最后对古地理演化的成因进行了探讨,认为石炭—二叠系陆表海沉积主要受控于该时期全球海平面的变化,Sq1与Sq2之间的海侵转换面为稳定构造环境下的全球突发性海侵、南高北低的盆地基底与北缘稳定的物源共同造成的。

Based on the study of sedimentary facies,biostratigraphy and stack patterns of parasequences,epicontinental depoisit of Permo-Carboniferous is divided into 3 sequences in Southern North China,which mean 3 trangressional circles.After that this article reconstructs paleogeography both in sequence and at maximum flood surface.It is found that source area lies in the north,and Sq1 develops a small-scale and short-term transgression,which is from NE.However,transgression in Sq2 reaches the top almost submerging the whole area,and changes its direction from NE to SE.Sq3 keeps the same land-sea distribution with Sq2,while trangressional area retreats to the south.Finally the genesis of paleogeographical evolution is discussed,and it is thought that epicontinental depoisit is dominated by global transgression,and transitional surface between Sq1 and Sq2 results from the synthesis of global sudden transgression,basin basement high in the south and low in the north,and stable source from the north in inactive tectonic setting.