| 大同云岗矿区井下陷落柱中的地开石 |
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| 引用本文： | 贾炳文,郝临山.大同云岗矿区井下陷落柱中的地开石[J].沉积学报,1987,5(1):77-85. |
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| 作者姓名： | 贾炳文 郝临山 |
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| 作者单位： | 1.山西矿业学院地质系; |
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| 摘 要： | 大同云岗矿区下侏罗统大同组顶部煤层附近的井下陷落柱中,充填有团块状、细脉状、网脉状白色粘土矿物。经物理光性研究、电镜、差热、X射线及红外光谱分析,确证其为特殊产状和成因的地开石。该地开石仅分布地下深300-400m处的井下陷落柱中,并与自生黄铁矿共生,按地热增温率估算,最高温度不超过15℃。显然,本区地开石是在常温还原环境下,在流经煤层的弱酸性地下水作用,由陷落柱中铝硅酸盐矿物,经过长期溶蚀分解而成。
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| 关 键 词： | 地开石 常温还原环境 陷落住 自生黄铁矿 大同云岗矿区 |
| 收稿时间： | 1985-05-20 |
DICKITE FROM DOWNCAST PILLAR IN THE SHAFT OF YUNGANG COAL FIELD,DATONG |
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| Institution: | 1.Shanxi College of Mining;2.Datong School of Coal Technology |
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| Abstract: | Dickite found in the shaft of Yungang Coal Field occurs in downcast pillar close to coal seams at the top of Datong Formation of Middle Jurassic. It fills in pores and cracks of rocks, being in spotted block and network of vein. The main characteristics of this mineral are as follows : it is white-powdery aggregate with well lubricating,in most cases, its crystal takes the shape of hexa- gonal tabular;refractive index : Ng = l.567-1.568, Nm =1.563-1.564, Np = 1.561-1.562 Ng-Np=0.006 Ng//b, ApΛ(010)CΛNp=11°αΛNm=15°, (+) 2V=65°, parallel extinction, length slow. Under the scanning electromicroscope, its shapes are hexagonal prism or pagoda-like. Its chemical compositions are : SiO2 = 46.54%, Al2O3 = 38.99%, H2O+ 13.93%, SiO3: Al2O3 = 202 : 100. Its thermography curve has a intense endothermic peak at 670°, the curve is gently slope in the side of lower temperature and steeply in the side of higher temperature. In the figure of X-ray diffraction curves, peaks at d (021) =4.2442, d (012) = 3.9549,d (022) =3.7855 appear in the range of 2θ = 20°-24°;and between 2θ = 34°and 40°,four continnuous diffraction peaks appear.In the infrared spectrogram absorption, peaks at 3708,3640,3614cm(-1) occur in high frequency range, the frequency is from higher to lower, while the intensity of absorption peaks is from weak to strong. All of these data fully prove that the dickite from this district is similar to that from other districts. Owing to the fact that this mineral is found at the depth of about 400m under the earth's surface and intergrows with pyrite, the dickite may be formed in the condition of the reducing environment with less than 15℃ temperature. |
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