| 柴达木盆地粘土矿物特征及其演化 |
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| 引用本文： | 赵东升,贺鹏,孔红喜,郑海鹏,雷振锋.柴达木盆地粘土矿物特征及其演化[J].沉积学报,2001,19(1):66-70. |
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| 作者姓名： | 赵东升 贺鹏 孔红喜 郑海鹏 雷振锋 |
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| 作者单位： | 青海油田勘探开发研究院 |
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| 摘 要： | 对柴达木盆地下侏罗系河流夹沼泽相沉积的第三系以来湖相沉积的粘土矿物进行了X射线衍射、电镜等分析和观察，在此基础上讨论粘土矿物的成因，母岩分布和性质、水介质条件和古气候对粘土矿物形成和演化的影响，并通过粘土矿物含量和组合对比，讨论粘土矿物的继承性和粘土矿物组合差异的原因。
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| 关 键 词： | 柴达木盆地 粘土矿物 成因 演化 继承性 湖相沉积 古气候 |
| 文章编号： | 1000-0550(2001)01-0066-05 |
| 修稿时间： | 1999年11月28日 |
Characteristics and Evolution of the Clay Minerals in Qaida m Basin |
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| ZHAO Dong-sheng,HE Peng,KONG Hong-xi,ZHENG Hai-peng,LEI Zhen-feng.Characteristics and Evolution of the Clay Minerals in Qaida m Basin[J].Acta Sedimentologica Sinica,2001,19(1):66-70. |
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| Authors: | ZHAO Dong-sheng HE Peng KONG Hong-xi ZHENG Hai-peng LEI Zhen-feng |
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| Abstract: | The Qaidam basin is a non-marine, petroliferous basin on the northeastern margi n of the Qinghai-Tibetan Plateau, with an area of about 120,000 km2. Almost a ll strata are cropped out except Archaean group. The oil and gas discovered are distributed mainly in the reservoir of Jurassic(J1),Tertiary(R) and Quaternary (Q). Jurassic section is mainly composed of fluvial facies and offshore shallow lake deposition, interbedded with paludal sediment, the lithology is charac teristic of sandstone and mudstone, interbedded with coals. However, Cenozoic is composed of lucustrine and fluvial facies, and the lithology is characteristic of sandstone, mudstone, carbonate rock, interbedded with salt-rock, gypsum, with the palaeosalinity ranging 15‰～60‰.
Illite, illite-smectite, montmorillonite, chlorite, kaolinite and a small amoun t of chlorite-montmorillonite, palygorskite,holloysite are major clay mineralsin Qaidam basin. The clay mineral in sandstone is considered to be automorphic c rystal which is produced in diagenetic period. The monoblastic texture of illite , kaolinite and chlorite in mudstone is anhedral crystal, and its smooth, irregular outline reflected the terrigenous genesis of clay mineral.
The clay mineral contents vary with different depth and horizon. The kaolinite c ontent is 44.4% in J1 and 5.6% in E13-E23. The chlorite content va ry between 18.9％～12% in Cenozoic．However, it decreases to 9.9% in Jurassic. M ontmorillonite is concentrated in Quaternary and modern sediment. The con tent of illite-smectite in N1-N32 is 42.3% in highest, and it lacks in mo dern irregular sediment. The content of illite in J1 section decreases to 29.1% .The content of smectite in illite-smectite decreases as the strata get o l der or burial depth increase. There are 5 kinds of clay mineral combination I.e. I-CH,I-S(+I/S), S(+I/S)-I, K-I or K-S(+I/S), of which I-CH or I-S(+I/S) is main ly contributed in Cenozoic, K-I or K-S(+I/S) is in J1 lower-Jurassic. S(+I/S) -I is in N1-N32 section.
It is warm and humid climate at Jurassic in Qaidam basin. The parent rocks consi sted by volcanics and metamorphite are subjected to strong chemical weathering to produce a great amount of kaolinite. Meanwhile, acidic water medium in coal-b earing strata creates a kaolinite-perserving environment. The characteristic of arid-semiarid-arid climate in Cenozoic represents that parent rocks mainly are subjected to physical wethering, next to chemical wethering, and it supports material basis for a great amount of illite formation. The rich K+ in water m edium creates an environment for kaolinite and smectite transforming to illite in Tertiary.
The transported trace shows clay mineral feature and margin outline in mudstone, reflecting clay mineral terrigenous genesis. The difference of clay mineral content is correspondent with palaeoclimte, parent rock property, and water medium condition. The special combination of clay mineral reflectes the inheritance of clay mineral genesis. |
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| Keywords: | Qaidam Basin clay mineral genesis evolution inheritance |
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