沉积地层中伊/蒙混层粘土矿物的晶体结构晶体化学研究  

Crystal Structure and Crystallochemistry Study on Illite/Smectite Interstratified Clay Minerals in Sedimentary Strata

作　　者：雷新荣[1] 刘惠芳[1] 陆琦[1] 

机构地区：[1]中国地质大学测试中心

出　　处：《沉积学报》1997年第1期98-103,共6页Acta Sedimentologica Sinica

基　　金：国家自然科学基金

摘　　要：不规则伊／蒙混层粘土矿物在沉积地层中广泛存在，通过对１７例伊／蒙混层粘土矿物样品进行系统研究得出：（１）沉积地层中的部分有序型伊／蒙混层矿物的晶层连接概率介于完全随机混层与机械混和物的连接概率之间；（２）伊／蒙混层中的蒙皂石晶层向伊利石的转化分两步完成：两层水蒙皂石单层水蒙皂石伊利石；（３）随着成岩作用的进行（埋藏深度增加），Ｉ／Ｓ中的Ｉ晶层含量增加，在此同时，Ｉ／Ｓ晶体结构中四面体片的类质同相代换增加，四面体电荷及总层电荷亦增加，匹配该增加部分电荷的是层间域Ｋ的含量明显增加；（４）在沉积地层中的Ｉ／Ｓ混层矿物中，Ｉ晶层具有白云母的成分特点，层电荷为０．７５左右；Ｓ晶层则具有纳蒙脱石的成分特点，层电荷为０．Irregular illite/smectite interstratified clay minerals(I/S) occur frequently in sedimentary strata. Three pure I/S samples from the sedimentary strata in Xinjing,China are analysed in this paper, and it can be seen that the illite layer in I/S has the thickness of 1.00 nm,but the smectite layer has two types in thickness,that is ,1.5 nm for a smectite layer with two layers of interlayer water molecule and 1.25￣1.26 nm for a smectite layer with a single layer of interlayer water molecule.It can be concluded from the above results that,during diagenesis, the smectite layers in I/S transform to illite layer by two steps,that is ,smectite layer with two layers of interlayer water → smectite layer with one layer of interlayer water → illite layer.It can also be seen that the layer linking probabilities of the I/S are between those of wholly random interstratification and those of simplely physical mixture of two types of crystallites,i.e. ,P I<P I.I ,P II.I ,P III.I <1.0. The structural formulae are calculated for 14 pure I/S samples from the drills of the Fuyu oilfield in Jilin Province according to their electron probe quantitative analyzing results. By regression analysis of 14 variables including elements and charge distribution among tetrahedral,octehedral,interlayer sheets of the I/S sampsles as well as X-ray diffraction results (ratio of two type layers) and the sample burial depth,it is concluded that along with the continuing of diagenesis (increasing of burial depths),the contents of illite layers in I/S obviously increase (correlation coefficient being 0.85), and the substitutions of Al for Si in the tetrahedral sheet and the tetrahedral charge as well as the layer charge also increase (the coefficients being 0.77,0.077,0.085,respectively).By plotting of the contents of Si versus K and Na+2Ca versus K per formula,it can be seen that the illite layer in the I/S of sedimentary strata has a chemical composition chracteristic of muscovite with the layer charge of 0.75,and the smectite

关 键 词：沉积地层 粘土矿物 晶体结构 晶体化学 矿物晶体 

分 类 号：P578.94[天文地球—矿物学] P573[天文地球—地质学]