西藏搭格架热泉型铯矿床矿物学与矿石组构特征及地质意义

Characteristics and geological significance of mineralogy and fabrics for the hot spring cesium deposit occurring within the Targejia district,Tibet.

在查明搭格架铯矿床产出的地质背景、成矿阶段及其年龄、地球化学与同位素组成的基础上,本文较为系统地研究了硅华的矿物学与组构特征,加深了对硅华形成演化过程的认识。研究表明成矿早期,矿石中存在大量的石英,晚期全为蛋白石。粒状蛋白石自早到晚均有出现,胶状蛋白石主要出现于晚期。早期矿石出现脱水造成的菜花状、粗粒块状与粗大孔隙状构造及溶蚀结构。晚期出现细粒块状与细小孔隙状构造。在第3阶段存在硅藻 Denticula 属,体现出低温阶段的特征。由早到晚,矿石的 SiO_2呈降低趋势,而(Na_2O+Al_2O_3+K_2O+CaO)与 Cs_2O 呈升高趋势,是随着矿石中 SiO_2有序度的降低而其它成分被保留在晶格中所致。

On the basis of investigating the characteristics of the geological background, ore-forming stages and its geologic age, geochemistry and isotope of Targejia hot spring-type cesium deposit, this article systematically studies the characteristics of mineralogy and fabric of gyserite, which will show great significance for understanding ore-forming process of this deposit. The study indicates that the early stage contains a lot of Quartz, but the late stage only consists of opal. Grannular opal exists from early to late stages while colloform opal mainly occurs in the late stage. The cauliflower-liked, megagrained massive, pore and corrosion structures exist in early stage. Fine-grained massive and pore structure exist in late stage. In the 3nd stage, there is Denticula genus of diatom, which has the characteristics of low-temperature stage. From early to late stage, the content of SiO2gradually falls while contents of （Na2O ＋ Al2O3 ＋ K2O ＋CaO） and Cs2O rise. The reason is that impurity components are not expelled from crystals with the falling degree of SiO2-ordering.