| 江西龙南花岗岩稀土风化壳中粘土矿物的研究 |
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| 引用本文： | 杨主明.江西龙南花岗岩稀土风化壳中粘土矿物的研究[J].地质科学,1987,0(1):70-80. |
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| 作者姓名： | 杨主明 |
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| 作者单位： | 中国科学院地质研究所 |
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| 摘 要： | 本区燕山早期花岗岩发育的风化壳中的粘土矿物以高岭石和埃洛石(7Å)为主;蒙脱石、三水铝石及其它为新查明矿物。据粘土矿物组合特征,自风化剖面深部到地表分为三个带:含蒙脱石带,高岭石和埃洛石(7Å)带,含三水铝石带。本文探讨了矿物在风化过程中的生成演化顺序,并进行了热力学的解释。据各带粘土物质的阳离子交换量与稀土含量变化的不一致关系认为,稀土在C带中的富集是化学风化的结果,与粘土矿物组合无关。
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| 关 键 词： | 埃洛石 风化 稀土元素 江西龙南 |
| 收稿时间： | 1985-01-01 |
| 修稿时间： | 1985-01-01; |
A STUDY ON CLAY MINERALS FROM THE REE-RICH WEATHERED CRUST DEVELOPED ON THE LONGNAN GRANITE IN JIANGXI |
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| Yang Zhuming.A STUDY ON CLAY MINERALS FROM THE REE-RICH WEATHERED CRUST DEVELOPED ON THE LONGNAN GRANITE IN JIANGXI[J].Chinese Journal of Geology,1987,0(1):70-80. |
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| Authors: | Yang Zhuming |
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| Institution: | Institute of Geolagy, Academia Sinica, Beijing |
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| Abstract: | The clays of the weathered crust developed on an early Yanshan granite are studied by XRD, DTA, IR, TEM and SEM. The study shows that kaolinite and 7 A halloysite are the predominant constitution in clays, and montmorillonite, micavermiculite irregularly mixed layer mineral, Al-vermiculite and gibbsite are investigated for the first time in the area. The clay minerals are divided into three zones from the depths to the surface in the profile: montmorillonite containing zone, kaolinite and halloysite (7 A) zone, gibbsite containing zone, designated with D, C and A + B zone respectively. Halloysite (7 A) in C zone is more abundant than the others. The crystallinity of kaolin tends to vary from wellcrystalline to poor-crystalline upwards in the profile.The clay minerals formed from the weathered feldspar. The weathering sequence is: feldspar- allophane- halloysite- kaolinite- gibbsite, and feldspar- montmorillonite- kaolinite- gibbsite. Mica was weathered later than the feldspar to form mixed layer mineral and vermi-culite. Thermodynamic calculation shows that the activity of H4SiO4 and the condition of pH at the weathering environment are responsible for the stability of clay minerals and their distribution in zones.The cation exchange content determined in clays varies in a range of 16.5-16.4-12.0-10.8 (meq/100g) from D to A zone, and REE content in 1122.9-1547.3-386.9-291.1 (ppm). However, the cation exchange content of the clays is not consistent with the REE content in the zones of the profile. It is considered that the main cause which brings about the enrichment of REE in C zone of the weathering profile arises from chemical weathering process, not from the different clay mineral association. |
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| Keywords: | kaolinite halloysite weathering rare earth element (REE) |
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