华北晚古生代海平面变化及其层序地层响应

依据沉积学、煤地质学、层序地层学、古生物学等多学科综合方法,对华北地区晚古生代地层进行层序地层分析,并研究了相对海平面升降和其层序地层学响应,研究结果表明:研究区晚古生代地层存在着8种层序界面,主要包括古构造运动面、古生物间断面、大面积泥炭化沼泽化界面、陆表海低水位砂体底界、盆地转换界面、大范围冲刷面、大面积暴露面和硅质海绵岩等;依据界面的划分原则可以将研究区地层划分出1个盆地充填层序、3个构造层序(相当于二级层序)和7个三级层序;分析发现,基于层序格架下的相对海平面升降可以分为层序1-层序3的短期大规模海侵阶段及长时间海退阶段和层序4-层序7的长时期的海退阶段.在此基础上,依据海平面变化曲线及其层序地层响应特征发现华北晚古生代海平面变化具有周期性与复合性和高频性与事件性等特点.

The sea-level change and its response to the Late Paleozoic sequence stratigraphy in North China

Based on data from such disciplines as sedimentology,coal geology,sequence stratigraphy and paleontology,the authors studied the sequence statigraphy,the relative sea-level fluctuation and its response to sequence stratigraphy.The results show that there are eight sequence surfaces,which mainly include palaeostructural surface,palaeontologic gap surface,large-area peat-moor surface,low stand floor surface of continental sea,transpressional basin surface,large-area buried erosion surface,large-area exposed surface,and siliceous spongolite surface.According to the principle of sequence stratigraphy division,the authors recognized one basin filling sequence,three tectonic sequences(second-grade sequences) and seven third-grade sequences.Two stages of relative sea level can be found based on the sequence stratigraphy framework.The first stage is from sequence 1 to sequence 3,which is composed of a short-time transgression and a long-time regression.The second stage is from sequence 4 to sequence 7,which is a long-time regression.On such a basis,the authors hold that the sea-level change of North China in Late Paleozoic can be studied by the sea-level curved shape and its response to sequence stratigraphy.The first characteristic is periodicity and compounding,and the second characteristic is high frequency and event synchronization.