黑色页岩化学风化过程的微观机制及演化

针对黑色页岩化学风化系统的复杂系统演化问题,通过X射线衍射(XRD)试验、扫描电子显微镜和X射线能谱(SEM-EDS)试验,从风化过程的微观结构变化和非平衡热力学过程出发,对黑色页岩化学风化剖面中不同风化层的矿物成分和微观结构变化进行对比分析,探讨黑色页岩化学风化的微观机制,同时利用非平衡态热力学理论和耗散结构原理分析黑色页岩化学风化系统的耗散结构的形成过程及化学风化演化规律。研究表明:在黑色页岩化学风化过程中酸性水的侵蚀作用下,易溶性矿物溶解、次生矿物生成及离子交换吸附作用,促使矿物成分发生转变;同时矿物颗粒间的连接方式发生了改变,也促使岩石内部产生大量微孔隙。黏土矿物和含水硫酸盐矿物的吸水膨胀及失水收缩过程,使岩石内部产生不均匀应力,进一步改变岩石内部的微孔隙,促进化学风化进程。黑色页岩化学风化系统是一个开放的复杂系统,利用非平衡热力学计算认为该系统是不可逆过程,且经历了近平衡阶段和远离平衡阶段,最终可形成具有一定稳定性的耗散结构。

Research on micro-mechanism and evolution of black shale in chemical weathering process

Aiming at unraveling the complex issue of system evolution in chemical weathering process of black shale,the research on micro-mechanism and evolution of black shale is carried out in such aspects as microstructure changes,non-equilibrium thermodynamics and dissipative structure during weathering processes.On the basis of geology analysis,combined with the X-ray diffraction (XRD) test,scanning electron microscopy and energy dispersive X-ray spectrometer test (SEM-EDS),the mineralogical composition and structure of black shale in different weathering zones and its original shale are analyzed contrastively,and the chemical weathering micro-mechanisms of black shale in weathering systems are discussed.The non-equilibrium thermodynamics theory and dissipative structure principle are also used to systematically analyze the formation process of dissipative structure and weathering evolvement in chemical weathering systems of black shale.It is indicated that the minerals are translated through the mineralogical dissolution,secondary mineral generation,ion exchange and adsorption effect.The connection between mineral grains is changed and a large number of micro-pores are generated by erosion under action of acidic water during chemical weathering process of black shale.Non-uniform stress between mineral particles occurs in micro-pores,where the clay minerals and some sulfate minerals fill in the pores,and then change the internal micro-structure of shale in further.The chemical weathering system of black shale is an open and complex one and it is an irreversible process system in the non-equilibrium thermodynamics calculation.It reveals that the weathering system generally undergoes three stages:near-equilibrium state,far-from-equilibrium state,and ultimately,generated the stable dissipative structure.