| 摘要: |
| 在江汉平原濒临长江北岸的洪湖及其周围的土壤中,分别取得沉积物柱状钻孔样品和土壤剖面样品,用偏光显微镜和电子显微镜观察了2.5kaBP以来形成的三种湖相粘土的微结构特征,并以此解释的其成因和沉积环境.0.9-2.5kaBP期间形成的青色粘土的典型微结构有:凝胶结构、细颗粒粒径和小孔隙、矿物颗粒低圆度和淡水中心冈硅藻等生物框架结构.主要是有机质胶体与粘土胶体相互作用形成的.此期间,河流带入湖泊的泥沙少,洪湖拥有一个开阔、稳定、浮游生物较多的淡水湖泊环境.0.45-1kaBP期间形成的黑色粘土的主要微结构类型有:凝胶结构、大的圆孔隙和植物纤维等生物框架结构、呈双峰分布的孔隙.它主要是由于维管束植物残体大量积累形成的.当时洪湖湖水变浅,大量挺水植物生长,湖泊已经沼泽化了.0.45kaBP以来形成的灰色粘土的微结构类型主要有:絮凝结构、较大的微孔隙和颗粒粒径、矿物颗粒较高的圆度等.物源主要来自河流带来的泥沙,当时河湖相通,河流入湖水沙量大. |
| 关键词: 微结构 湖相粘土 成因 江汉平原 洪湖 |
| DOI：10.18307/20010403 |
| 分类号: |
| 基金项目:国家自然科学基金(49501003);中国科学院创新工程重点项目(KZCX2-310-01-02);中国科学院"九五"重大项目(ZK951-A1-202-01-03);东湖湖泊生态系统试验站(200105) |
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| Microfabric Properties of Three Types of Lacustrine Clay in the Honghu Lake and Their Sedimentary Environments |
|
YI Chaolu
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Department of Environmental Sciences, Institute of Geodesy and Geophysics, CAS, Wuhan 430077, P. R. China
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| Abstract: |
| Core samples were collected from the Honghu Lake and in paddy soil profiles around the lake.Using SEM and polarizing microscope, the microfabrics property, grain size and organic matter content of three types of lacust rine clays were examined.The microfabrics of green clay formed during 0.9-2.5kaBP are illustrating gelat inous texture, fine particles, small voids, subangular to angular surface texture of the particles, which also has a relatively hig her content oforg anic matter (average 3.14%).The green clay was formed by the interaction of the colloids of suspended clay sediment with that oforganic matter.The Hong hu lake had a open, stable environment enriched in plankton diatoms, with less sediment from the river during this period.The black clay that was formed during 0.45-1kaBP was gelatinous texture, larger circular voids, with plant remain frame.Its void size dist ribution display sbimodes.The origin is ascribed to the accumulation of great amount of aquatic vascular plant.During the period, the lake was shallower than the present with a lot of vescular plants.The gray clay formed since 0.45kaBP was agglutinational texture, larger sizes of voids and grain particles, orientation of flaky hydromica, subrounded to subangular surface texture of the particles, indicating certain inf luence by the sediment from river discharge. |
| Key words: Microfabric lacustrine clay origin sedimentary environment Hong hu Lake Jianghan Plain |
