【摘要】 计算了各种可能形成伊利石的反应的热力学条件,在此基础上分析了成岩流体的化学性质对伊利石形成的影响。结果表明,(1)钙长石的伊利石化具有最低的吉布斯自由能增量,该反应主要是在同生到埋藏成岩作用的早期阶段,由富钾的海源流体作用形成的。钠长石和钾长石形成伊利石的反应需要酸性流体的a(K+)/a(H+)(活度比值)保持在伊利石的稳定域。(2)高岭石形成伊利石时流体的a(K+)/a(H+)比值要足够高,以克服伊利石的成核动力学屏障,能够满足其反应需要的流体可能是有机酸,它能溶解钾长石,同时进一步溶解其他易溶矿物(如碳酸盐矿物)从而达到足够高的a(K+)/a(H+)比值,而以CO2作为主要溶解介质时会导致碳酸盐矿物的沉淀。(3)钾长石与高岭石反应形成伊利石通常需要温度超过120℃,这时由钾长石溶解所控制的a(K+)已能够克服伊利石的结晶动力学屏障。该反应需要成岩环境在早成岩期受海源流体影响,以使在由长石溶解形成明显数量的高岭石同时能够保存足够数量的钾长石。(4)钾长石与高岭石反应形成伊利石时若有Na+的输入可导致钠长石的沉淀,该反应在较高温度下发生,钾长石的溶解和钠长石化受高岭石的伊利石化而消耗K+的动力学作用控制。更多还原

【Abstract】 Based on the calculation of chemical thermodynamic conditions to form authigenic illite,the influence of chemical character of the diagenetic fluid h as been analyzed.The results show that:(1) The reaction of anorthite conversio n to illitization has the lowest Gibbs free energy increment.It is more likely to occur in early diagenetic stage on the action of K+-rich fluid related to the sea water.The reaction of albite or K-feldspar forming illite should require a cidic fluid K+/H+ activity ratio,kept in the illite stability field.(2) Kaolin illitization is promoted by a high K+/H+ activity ratio which allows the kineti c barrier to illite nucleation to be removed.This may need K-feldspar to be dis solved by organic origin fluids,and additional proton-consuming by other react ions(e.g.carbonate dissolution) is need to reach critical K+/H+ activity ratio.But with CO2 as the major dissolution media will lead to precipitation of carb onate minerals.(3)The reaction of K-feldspar and kaolinite to form illite usual ly requires temperatures to exceed 120℃.Then,the K+/H+ activity ratio control led by K-feldspar solubility may overcome the kinetic barrier of illite crystall ization.This reaction requires diagenetic environment influence by marine fluid in the early diagenesis,which can preserve enough K-feldspar while the feldspar dissolves to form significant amount of kaolinite.(4)External source of Na+ ca n lead to precipitation of albite when the K-feldspar and kaolinite react and fo rm illite.This reaction will occur at higher temperatures.The solubility and a lbitization of K-feldspar is controlled by kinetic action of kaolin illitization to consume K+.更多还原