地质科技情报2011，Vol.30Issue(1)：20-25,6.
伊利石形成相关反应的热力学计算及其对砂岩成岩作用研究的意义
Thermodynamic Calculation of lllite Formation and Its Significance on Research of Sandstone Diagenesis
摘要
Abstract
Based on the calculation of chemical thermodynamic conditions to form authigenic illite, the influence of chemical character of the diagenetic fluid has been analyzed. The results show that: (1) The reaction of anorthite conversion 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 acidic 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 kinetic barrier to illite nucleation to be removed. This may need K-feldspar to be dissolved by organic origin fluids , and additional proton-consuming by other reactions (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 carbonate minerals. (3)The reaction of K-feldspar and kaolinite to form illite usually requires temperatures to exceed 120℃. Then, the K+/H+ activity ratio controlled by K-feldspar solubility may overcome the kinetic barrier of illite crystallization. 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+ can lead to precipitation of albite when the K-feldspar and kaolinite react and form illite. This reaction will occur at higher temperatures. The solubility and albitization of K-feldspar is controlled by kinetic action of kaolin illitization to consume K+.关键词
自生伊利石/碎屑岩成岩作用/成岩流体/热力学Key words
authigenic illite/ clastic diagenesis/ diagenetic fluid/thermodynamics分类
天文与地球科学引用本文复制引用
魏文文,黄思静,郇金来..伊利石形成相关反应的热力学计算及其对砂岩成岩作用研究的意义[J].地质科技情报,2011,30(1):20-25,6.基金项目
国家重大科技专项(2008ZX05001-004-003) （2008ZX05001-004-003）
