摘要
天水地区含坡缕石粘土岩赋存于上第三系上部,为一套灰白色粘土质碳酸盐岩和碳酸盐质粘土岩岩系,可分为四个沉积区,其中北部的秦城—北道沉积区和清水沉积区的坡缕石含量较丰富。粘土岩主要由伊利石、绿泥石、蒙脱石、坡缕石、方解石和白云石等组成。坡缕石在电镜下观察多为细小纤维和纤维集合体。本区含坡缕石粘土的微量元素含量偏高,其中Rb/K值为0.0048～0.0069;(Br×10~3)/Cl值多数为110～650;δ^(13)C值为-3.14～-5.65;pH值为8.32～9.70。作者认为天水地区含坡缕石粘土形成于弱碱性-碱性的淡水-半咸水环境中。
Palygorskite-bearing clay rocks in Tianshui district exist in the upper of Neogene system, which is a set of rocks composed of grey-white clayey carbonate rocks and calcareous clay rocks. It can be divided into four sedimentary provinces. In the northern part, Qincheng—Beidao sedimentary province and Qingshui sedimentary province much rich in palygorskite. Clay rocks mainly consist of illite, chlorite, montmorillonite, palygorskite, calcite, dolomite and so on. palygorskites mainly take the shape of fibre and fibrous aggregate under electronic microscope. In this area, the contents of trace elements of palygorskite-bearing clay are higher. Rb/K is0.0048～0.0069; (Br×10~3)/Cl is 110～650 (most);δ^(13)C is-3.14～-5.65; pHis 8.32～9.70. Therefore, the author considers this palygorskite-bearing clay in studied area is formed in a fresh—brackish water environment of weak alkaline—alkaline
