华北北部晚寒武世层序地层及海平面变化研究——兼论与北美晚寒武世海平面变化的对比

STUDY ON SEQUENCE-STRATIGRAPHY AND SEA-LEVEL CHANGES OF LATE CAMBRIAN IN NORTHERN PART OF NORTH CHINA—? ISCUSSION ON THE CORRELATION OF SEA-LEVEL CHANGE WITH THAT OF NORTH AMERICA

华北北部晚寒武世地层以发育风暴砾屑灰岩及生物丘灰岩著称 ,包括崮山组、长山组和凤山组。在该套地层中 ,主要发育潮下型碳酸盐米级旋回层序 ,根据米级旋回层序在长周期层序中的有序叠加形式 ,可识别出 4个三级层序。这些层序的典型特征是 :层序界面为淹没不整合面 ,层序的相序序列以“深缓坡相—浅缓坡相”为特征 ,从而构成特殊的“CS(?) +HST”序列。由各剖面点的古水深变化曲线 ,可以定性地综合出晚寒武世的海平面变化曲线。与北美晚寒武世海平面变化曲线相对比 ,既存在相似性更存在差异 ,说明了长周期海平面变化既受全球性海平面变化的控制 。

The Late Cambrian strata in the northern part of North China are well known for the development of storm calcirudite and bioherm limestone, which include Gushan, Changshan and Fengshan Formations. In this set of strata, carbonate meter scale cyclic sequeuces of subtidal type are mainly developed. Four third order sequences are discerned in terms of the regularly vertical stacking patterns of meter scale cyclic sequence. The typical natures of these third order sequences are as follow: sequeuce boundaries are marked by drowned unconformities and their correlative surface, the facies succession of them is characte ristic of “deep ramp—shallow ramp”, so the special succession of “CS(?)+HST” is formed. According to the changing curve of paleowater depth in each sections, the curve of sea level changes of Late Cambrian in northern part of North China could be synthesized qualitatively. The correlation of Late Cambrian sea level changes between North America and North China shows that not only is there similarity but also difference. So it could be concluded that the long term sea level change is controlled by global changes as well as regional changes.