某些矿物中同心层状鲕(豆)粒的自组织成因

OOIDS (PISOLITES) WITH CONCENTRICALLY RHYTHMIC ZONING IN SOME MINERALS AND THEIR SELF-ORGANIZATION ORIGIN

本文首先综述了矿物中同心层状鲕(豆)粒的基本特征,接着提出该鲕状结构的二阶段成因模式(早期胶团从沉积物中的快速形成和晚期胶团在自催化反馈机制的作用下的有序化)。最后,用自组织(耗散结掏) 理论和动力学分析方法揭示出如下结论:①自催化反馈机理是胶团中杂质元素的催化结晶;②胶团在有序化过程中能形成时-空有序的自组织结构即鲕粒同心层;③胶团中凝胶浓度和杂质元素浓度在相空间内为一极限环,定态胶团失稳后将沿着极限环闭轨演化并最终形成同心层状矿物鲕粒。

This paper presents the common features of ooids (pisolites) with concentrically rhythmic zoning in some minerals. A two-stage genetic model has been proposed to illustrate the formation mechanism of oolitic and pisolitic textures, i. e., the early stage at which gel lumps were growing rapidly from sedimentary materials and the late stage at which gel lumps ordered owing to the autocatalytic feed-back mechanism. Finally, based on the selforganization (dissipative structure) theories and dynamical analysis, it is concluded that (1) the autocatalytic feed-back mechanism refers to autocatalytic crystallization due to the catalytic effect of impure elements in the gel lumps; (2) the ordered tempo-spatial self-organization structure, i. e., concentrically rhythmic zoninz in the ooids (pisolites) was formed in the ordering process or gel lumps; (3) the limit-cycle is illustrated in the phase space composed of gel and impure element concentrations in gel lumps. When gel lumps of steady state lose stability, the system will evolve along the closed locus of the limit-cyele and finally the ooids(pisolites)with concentrically rhythmic zoning are formed. To find out the ordered phenomena feed back mechanism is an effective way to study self-organizational textures.