碱性地层水对火山碎屑岩改造作用的实验研究

以塔木察格盆地火山碎屑岩(流纹质凝灰岩、沉凝灰岩)为研究对象,通过密闭容器中地层水—火山碎屑岩相互作用的水热实验,研究了不同温度下碱性地层水对火山碎屑岩成分的改造.研究显示:在碱性地层水作用下,火山碎屑岩以石英溶解为主,且随着温度的升高,石英的溶解度逐渐加大,而长石及碳酸盐矿物的溶蚀较弱;同时,通过扫描电镜(SEM)的观察发现:流纹质凝灰岩在100,120,140,160℃下样品表面有钙十字沸石生成;沉凝灰岩在100℃时有方解石生成,在120℃和180℃时样品表面有钙十字沸石生成.结合南贝尔凹陷石英保存完好,长石、碳酸盐矿物溶蚀溶解较强的特征,表明碱性流体对该区火山碎屑岩次生孔隙贡献较少. 

Experimental study on reformation of volcanic clastic rocks by alkaline formation water

The hydrothermal experiments of volcanic clastic rocks chosen from the Nanbeier Sag of the Tamtsag Basin and formation water were researched under different temperatures in a closed container.The results show that quartz can be dissolved by alkaline formation water and the dissolution intensity will be enhanced with the increasing of temperature;on the contrary,the dissolution degree of feldspar and calcite is very low.Meanwhile,by scanning electronic microscope (SEM),phillipsite is found on the surface of rhyolitic tuff sample (at the temperature of 100,120,140 and 160℃) and sedimentary tuff sample (at the temperature of 120 and 180℃);calcite is found on the surface of sedimentary tuff at 100℃.Considering the good preservation of quartz and strong dissolution of feldspar and carbonate,it is proved that the formation water contributes few to the secondary poro-sity of the Nanbeier Sag of the Tamtsag Basin.