| 海绿石质凝缩层－克拉通盆地层序地层划分对比的关键──华北寒武系凝缩层的特征和含义 |
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| 引用本文： | 葛铭 Tucke.,M.海绿石质凝缩层－克拉通盆地层序地层划分对比的关键──华北寒武系凝缩层的特征和含义[J].沉积学报,1995,13(4):1-15. |
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| 作者姓名： | 葛铭 Tucke. M |
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| 作者单位： | 1 中国地质大学 北京 100083; |
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| 基金项目： | 国家自然科学基金,英国皇家学会－中国科协和＂八五＂国家基础性研究重大关键准攀登项目 |
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| 摘 要： | 凝缩层（ＣＳ）是当代层序地层学和沉积学研究的热点之一。作者首次在华北地台寒武纪层序中发现了一系列海绿石质凝缩层（段）。文中重点论述了凝缩层的相带分布、地球化学及其特征自生海绿石的形成演化等，给出了一个克拉通盆地Ⅲ级海平面变化周期的层序地层、年代地层模型及其凝缩间断时间过程。富钾海绿石及其丰度是鉴定凝缩层、其时限和级别的最佳标准。本文从全球海平面变化观点给凝缩层赋予新定义。研究证明，海绿石质凝缩层是克拉通盆地识别最大海泛期和进行层序地层对比的关键。
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| 关 键 词： | 海绿石 凝缩层 最大海泛期 克拉通盆地 |
| 收稿时间： | 1994-06-02 |
Glauconitic Condensed Sections(CS): The Key to Correlation Of Sequence Stratigraphy in the Craton Basin──Characteristics and Implication of the Cambrian Condensed Section of North China |
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| Institution: | 1 China University of Geosciences, Beijing,China 100083;2 Department of Geological Sciences University of Durham,England |
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| Abstract: | Condensed sections (CS) are related to the maximum flooding stage (lag dePOsits) of a relative sea-level Change. They are present in each second and third order sequences in the Middle-Upper Cambrian strata.I. Main features of condensed sections(CS)1. Rock types and sub factes of condensed sections.CSs are composed of seven rock types which are distributed in three factes and five sub factes:Rock types:(1) Glauconitic siltstone-sandstone; (2) Glauconitic oolitic limestone 1 (3) Glauconitic Binclastic limestone; (4)Glauconitic micritic limestone; (5)Glauconitic storm calcirudite;(6)Glauconitic hardground; (7)Glauconitic clay.Three factes: inner shelf, middle shelf and outer shelf Five subfacies: (1) Quartz sandstone-siltstone and Glauconity; (2) Glauconitic oolitic limestome; (3) Glauconitic intraclastic muds; (4) Glauconitic muds and hardgrounds; (5) Deep water muds +phosphorus and manganese.2. Mineralogy and geochemistry of condensed sections.Glauconite, dolomite, pyrite, limonite and clays are the main mineral components of CSs.Chemical analyses of CSs have shown concentrations of some trace elements, such as Mn, lr,P,K and Ti, one of the most important features of condensed sections is the abundance of bingenic material.The potassium content and texture of glauconite permit the assessment of the evolutionary stage and duration of a condensed section. From this, it is apparent that the length of time for the development of CSs is in the range of 104～106 years. This is similar to the duration of the maximum flooding stage of second or third order sea level changes.Ⅱ. Conclusion1. A new concept of condensed section is given in this paper:A condensed section is a low--rate marine sedimentation unit which formed at the time maximum flooding close to the inflection-point from TST to HST during the long-term (2nd to 4th order cycle) global sea-level changes.2. Condensed sections are not only the products of maximum flooding and early highstand, but also the ties of TST and HST. They are the key stratigraphic units of sequence division and stratal correlation. Sea-level changes of the different orders result in the formation of condensed sediments. Studies of the maturity of glauconite can be used to distinguish different orders of sea-level changes. |
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