Wang Chao-wen, Chen Jiang-jun, Fang Qian, Yin Ke, Hong Han-lie
Guang Pu Xue Yu Guang Pu Fen Xi. 2015 Oct;35(10):2901-5.
X-ray diffraction (XRD) and Fourier infrared absorption spectroscopy (FTIR) were conducted to deepen our research on specific species and spectral characteristics of swelling clay minerals in the Pliocene sandstones in Xinghai, Qinghai province. XRD results show that swelling clay minerals are dominant clay minerals in the sandstones, which can be up to 97% in percentage. XRD patterns show 060 reflections of the samples occur both remarkably at 1.534 Å and 1.498 Å, indicating the samples contain physical mixtures of trioctahedral and dioctahedral swelling clay minerals, respectively. Further treatment of Li-300 degrees C heat and glycerol saturation shows the swelling clay minerals collapse to 9.3-9.9 Å with a partial expansion to -18 Å. This indicates the swelling clay minerals dominate montmorillonite and contain minor saponite. The montmorillonite shows no swelling after Li-300 degrees C heat and glycerol saturation because of Li+ inserting into the octahedral layers, which balances the layer charge caused by the substitution of Mg to Al. FTIR results show the samples are composed of a kind of phyllosilicate with absorbed and structural water, which is in agreement with the results of XRD. Absorbed peaks at 913, 842, 880 cm(-1), corresponding to OH associated with Al-Al, Al-Mg, and Al-Fe pairs, further indicates the minerals are dominant dioctahedron in structure. Meanwhile, absorbed peaks at 625 and 519 cm(-1), corresponding to coupled Si-O and Al-O-Si deformation, indicates parts of Si is replaced by Al in tetrahedron. The spectral characteristics of the samples are against the presence of beidellite and nontronite based on the results of XRD and FTIR, while demonstrating an,existence of montmorillonite. This study, to distinguish the specific species of swelling clay species in clay minerals, would be of great importance when using clay mineralogy to interpret provenance and climatic information.
进行了X射线衍射（XRD）和傅里叶红外吸收光谱（FTIR）分析，以深化对青海省兴海上新世砂岩中膨胀性粘土矿物的具体种类和光谱特征的研究。XRD结果表明，膨胀性粘土矿物是砂岩中的主要粘土矿物，含量可达97%。XRD图谱显示，样品的060反射在1.534 Å和1.498 Å处均有明显出现，表明样品分别含有三八面体和二八面体膨胀性粘土矿物的物理混合物。经过300℃锂热和甘油饱和处理后，膨胀性粘土矿物坍塌至9.3 - 9.9 Å，部分膨胀至-18 Å。这表明膨胀性粘土矿物以蒙脱石为主，含有少量皂石。由于锂离子插入八面体层，平衡了由镁取代铝引起的层电荷，蒙脱石在300℃锂热和甘油饱和处理后不再膨胀。FTIR结果表明，样品由一种含有吸附水和结构水的层状硅酸盐组成，这与XRD结果一致。在913、842、880 cm⁻¹处的吸收峰，对应于与铝-铝、铝-镁和铝-铁对相关的羟基，进一步表明矿物在结构上以二八面体为主。同时，在625和519 cm⁻¹处的吸收峰，对应于耦合的硅-氧和铝-氧-硅变形，表明四面体中的部分硅被铝取代。基于XRD和FTIR的结果，样品的光谱特征与绿脱石和钠云母的存在不符，而表明存在蒙脱石。这项区分粘土矿物中膨胀性粘土种类具体物种的研究，在利用粘土矿物学解释物源和气候信息时具有重要意义。
