松辽盆地东南隆起区营城组火山岩蚀变改造型膨润土类型、成因及分布规律——以九台市膨润土矿为例

松辽盆地营城组火山岩蚀变转化为膨润土或发生膨润土化现象较普遍，出露较大型的膨润土矿主要在九台银矿山一带。矿床与下伏沙河子组煤系地层呈不整合接触。通过火山岩岩性、岩石序列关系、微观特征及X-衍射分析等研究认为：膨润土类型可划分为低沸石型膨润土和高沸石型膨润土；珍珠岩、含角砾流纹质（玻璃质）凝灰熔岩和玻璃质火山碎屑岩为主要成矿原岩，成岩期后流体及流体的运移通道是决定其是否蚀变的主要因素；从成矿原岩转化为膨润土，即火山玻璃（珍珠岩）-沸石岩-膨润土的变化规律反应在岩石序列关系上表现为蚀变作用逐渐增强，岩石的硬度-颜色逐渐变弱，岩石的组构特征逐渐消失的过程；矿体发育厚度、横向连续性受火山机构的影响，具有很强的非均质性，一般在侵出相内+中带亚相、爆发相空落亚相和热碎屑流亚相是膨润土矿形成的最有利相带，另外岩性为玻璃质流纹岩的喷溢相也是膨润土形成的主要相带。

Type,Genesis and Distribution Regularities of the Bentonite of Volcanic Rock-Altered and Reformed Type in the Yingcheng Formation in the Southeastern Uplift of the Songliao Basin-Take Jiutai Bentonite Deposit as an Example

It is known that the volcanic rocks of the Yingcheng Formation were altered into bentonite in the Songliao Basin, and the major bentonite deposits in the area are located in Jiutai City. These deposits are in unconformable contact with the underlying coal-bearing strata of the Shahezi Formation. Based on studying on the lithology of volcanic rocks, lithological sequence, microfeature and X-inflection, etc., bentonite in the area could be divided into the low-zeolite and high-zeolite types；pearilte, liparitic (vitreous) ash-latite with breccias and vitreous volcaniclastic rock serve as the major mineralized rocks；The fluids and their passageways were the major factors that determined if alteration happened. With increased alteration from the mineralized rocks into bentonite, their alteration of the rocks became more intensive, and hardness more weak, color more white and gradually disappearing of the lithofabric features; The thickness and continuity of the orebodies are strongly affected by volcanic facies. Generally, the best zones of bentonite are inner subfacies and middle subfacies of extrusive facies and air-fall subfacies and thermo-offal fluid subfacies of explosive facies. Besides, the erupted facies of vitreous liparite also makes up a major zone for the bentonite.