广西巴吉地区全新世累托石粘土岩的发现及其矿物学研究

THE DISCOVERY OF HOLOCENE RECTORITE CLAYROCKSIN THE BAJI AREA, GUANGXI

在中国广西巴吉地区第四纪全新世发现累托石粘土岩层。主要矿物组成为累托石、少量伊利石、叶蜡石和高岭石。X射线分析显示，天然走向片累托石的d（001）=2．3994±0.011nm，经乙二醇处理后，d（001）=2．661±0．005nm，根据MacEwan的直接傅立叶变换法，计算了乙二醇处理后的累托石基面反射的傅立叶变换，并得出两种成分层的概率是PI：PM=0．499：0．501和VC=0．03，表明这是规则性极好的间层矿物。其主要化学组成是SiO2、Al2O3和H2O，微量元素Zr、Pb、Y、Sn含量高于地壳中克拉克值。还利用红外、差热和透射电镜、扫描电镜以及高分辨电镜研究了其矿物学特征。巴吉累托石粘土岩主要是由原生累托石粘土岩层经过侵蚀和搬运再沉积形成的。

Rectorite clayrocks were recognized in the Holocene series of the Baji area, Guangxi.The rocks are composed mainly of rectorite with minor amounts of illite, pyrophyllite and kaolinite. XRD analyses show that the rectorite has d(001) = 2. 3994 ± 0.011 nm. After treatment withethylene glycol it shifted to 2. 661 ±0.005nm. According to the MacEwan's direct Fourier transformation method, the Fourier transformation of the basal reflection by treatment with ethyleneglycol was calculated and the probabilities of two component layers are PI: PM =0. 499: 0. 501,and VC=0. 03. It is indicated that the rectorite is a well-regular interstratified mineral. Its mainchemical components are SiO2, Al2O3 and H2O, with trace amounts of Na2O, CaO, MgO, K2O andFeO. The contents of the minor elements Zr, Pb, Y and Sn are much higher than their clark values in the crust. IR, DTA, TEM, SEM and HRTEM were also conducted. The rectorite clayrocks in the Baji area are considered to have resulted from the resedimentation of primary rectoriteclayrocks following erosion and transport.