| 华北地台北缘奥陶系亮甲山组的碳酸盐复合海平面变化旋回层序 |
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| 引用本文： | 梅冥相.华北地台北缘奥陶系亮甲山组的碳酸盐复合海平面变化旋回层序[J].沉积与特提斯地质,1995(5):33-42. |
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| 作者姓名： | 梅冥相 |
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| 作者单位： | 中国地质大学 |
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| 摘 要： | 华北地台北缘亮甲山组地层中发育有六种碳酸盐米级旋四层序；ａ型和ｂ型属潮下型，其下部单元为钙质泥岩（ａ型）及薄层泥晶灰岩（ｂ型）．上部单元为颗粒泥晶灰岩（ａ与ｂ相同）；ｃ－ｆ型属环潮坪型，它们的上部单元均为薄层泥晶白云岩及泥质白云岩，其下部岩石单元：ｃ型为厚层及块状颗粒泥晶灰岩，ｄ型为局部白云石化颗粒泥晶灰岩，ｅ型为白云岩化颗粒泥晶灰岩，ｆ型为中厚层含少量颗粒的泥晶结晶白云岩。从ａ型到ｆ型正好构成一个米级旋回层序的环境变化谱系。根据米级旋回层序的有序垂直叠加形式，可以建立亮甲山组地层构成的复合海平面变化旋四层序：１个三级旋四层序包含３个四级旋四层序，１３－１５个五级旋四层序，６０余个左右的米级旋四层序．通过这项研究表明，在浅水地层中进行露头旋四层序研究时，米级旋回层序是基本工作单元，其有序垂直叠加形式是识别长周期旋四层序的关键．
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| 关 键 词： | 旋回层序，复合海平面变化，亮甲山组，奥陶系 |
| 收稿时间： | 1994/10/16 0:00:00 |
COMPOSITE SEA-LEVEL CHANGE CYCLIC SEQUENCES OF THE CARBONATES IN THE ORDOVICIAN LIANGJIASHAN FORMATION ON NORTHERN NORTH CHINA PLATFORM |
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| Mei Mingxiang.COMPOSITE SEA-LEVEL CHANGE CYCLIC SEQUENCES OF THE CARBONATES IN THE ORDOVICIAN LIANGJIASHAN FORMATION ON NORTHERN NORTH CHINA PLATFORM[J].Sedimentary Geology and Tethyan Geology,1995(5):33-42. |
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| Authors: | Mei Mingxiang |
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| Institution: | China University of Geosciences, Beijing |
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| Abstract: | Six types of the metre-scale carbonate cycles are recognized in the Ordovician Liangjiashan Formation on northern North China platform.Types a and b are assigned to the subtidal types,which consist of calcareous mudstone(Type a)and thin-bedded micritic limestone(Type b) in the lower units,and of grainy micritic limestone(the same in Types aand b).Types c to f are ascribed to the tidal flat types,which are all composed of thinbedded dolomicrostone and muddy dolostone in the upper units,whereas in the lower units,Type c consists of the thick-bedded and massive grainy micritic limestone;Type d is built up by the locally dolomitized grainy micritic limestone;Type e is made up of dolomitized grainy micritic limestone,and Type f represents the moderately thick-bedded micritic crystalline dolostone with a small amount of grains. It follows that Types a to f do well to form the hierarchy of the environmental changes of the metre-scale cyclic sequences.Based on the ordered vertical stacking patterns of the metre-scale cyclic sequences,the composite sea--level change cyclic sequences may be constructed for the strata in the Liangjiashan Formation.One third-order cyclic sequence comprises three fouth-order cyclic sequences, thirteen to fifteen fifth-order cyclic sequences,and sixty and more metre-scale cyclic sequences.The results herein have revealed that the metre-scale cyclic sequences may be used as the basic working units whose ordered vertical stacking patterns are believed to be the key to the identification of long period cycles in the study of outcrop cyclic sequences in the shallow--water strata. |
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| Keywords: | cyclic sequence composite sea-level change Liangjiashan Formation Ordovician |
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