桂北地区寒武系黑色页岩化学风化特征  

Chemical weathering characteristics of Cambrian black shale in northern Guangxi, China

作　　者：廖昕[1,2] 巫锡勇 朱宝龙[3] 

机构地区：[1]西南交通大学地质工程系,四川成都610031 [2]京都大学防灾研究所,京都宇治6110011 [3]西南科技大学土木工程与建筑学院,四川绵阳621010

出　　处：《中南大学学报（自然科学版）》2013年第12期4980-4987,共8页Journal of Central South University:Science and Technology

基　　金：国家自然基金科学基金资助项目(41172261);四川省科技支撑计划项目(2012SZ0051)

摘　　要：以桂北地区广泛分布的寒武系清溪组黑色页岩为对象，采集该区的黑色页岩和风化产物及酸性环境水，对岩样的矿物与化学成分、微观结构特征及酸性水的水化学特征进行分析，探讨该区黑色页岩的化学风化强度和风化产物的形成条件及其共生序列。研究结果表明：在桂北地区气候条件影响下，富含黄铁矿等硫化矿物的清溪组黑色页岩整体处于中等化学风化程度，并且其风化过程导致周围环境水的严重酸化（pH为2～3），还生成白铁矾、叶绿矾和黄钾铁矾等次生有害矿物。因此，在酸性水和次生膨胀性硫酸盐的共同作用下，黑色页岩发育区的岩体工程性质将极度弱化。Taking the Cambrian Qingxi Formation black shale as research object, which was widely distributed in northern Guangxi, black shale rocks, weathering products and acidic environment water were sampled to analyze the mineral and chemical compositions, microstructural features and hydrochemistry characteristics. The chemical weathering intensity of black shale as well as the formation conditions and paragenetic sequences of weathering products were discussed. The results show that under the influence of climatic condition in northern Guangxi, Qingxi Formation black shale is subject to moderate chemical weathering. In the process of black shale weathering the ambient environment water is acidized seriously （pH 2-3）. Furthermore, some secondary harmful sulfate minerals are generated, such as rozenite, copiapite and jarosite. Therefore, under the combined effects of acid water and secondary expansive sulfate minerals, the engineering properties of rock masses are weakened extremely. It is expected to provide some instructive significance for engineering geological hazards induced by black shale chemical weathering in this area.

关 键 词：黑色页岩 化学风化 硫化矿物 酸性水 共生序列 

分 类 号：P642.24[天文地球—工程地质学]