砂岩中的一种成岩作用标志

A Diagenesis Sign in Sandstone

砂岩中复晶粒的硅质增生胶结本质上属于共轴加大胶结范畴,它们往往见于分选较好,杂基较少,缺乏早期粘土环边的中—细粒砂岩中。主要表现是在石英岩屑、燧石、玉髓质等颗粒上的硅质增生环边。这些环边是由若干微粒石英组成的,每一微粒石英与邻接颗粒上的核心微粒的光性一致或大体一致。增生环边的发育直接受颗粒性质,组成粒的大小,杂质含量多少及颗粒上早期复盖物的有无和厚薄的控制,同时还与相邻同一孔隙空间的其它颗粒性质有关。石英砂岩、长石石英砂岩中的硅质增生胶结是在石英加大高峰期,Sio_2充足的酸性水条件下形成的。

Silic cemented multiplication of compound silic grains in sandstone belongs to the category of addened coaxial cementation, which is often found in better separated and . less imperity-containing mid-fine grain quartz sandstone arid feldspar quartz sandstone-Siliceous grains of quartz rocky fragments, flints, jades, etc. and are formed due to almost parallel arrangement of large quantity of micrograined quartz. They are addened parts of micrograined nuclei on adjacent grains. Siliceous multiplication cementation is caused during the highpeak time of addened quartz cementation of sandstone diagenesis sequence, formed under the condition of acid ?water of abundant SiO2. The main factors affecting siliceous multiplication cementation are as follows: 1. Sandstone components and texture features; 2. Shortage of early carbonaceous cementation and/or ring-side cementation of early self-yielding clay; 3. Other grain features of the same adjacent opening space.