条纹状磁铁矿岩形成机理初探

ON THE GENESIS OF STREAKED MAGNITITITE SKARN

本文通过对云南个旧矽卡岩带中的条纹状磁铁矿岩的地质产状、组份迁移、微区元素线扫描等研究认为:条纹状磁铁矿岩的形成应视为一种地球化学自组织过程。作者运用了 P.J.Ortoleva 等提出的过饱和—成核—沉淀这样一种具负反馈机制的理论模型,初步建立了条纹状磁铁矿岩形成的反应模型。

Based on the study of streaked skarn composed of magnitite and flurite-vesuvianite in Gejiu ore zone with respects to the field investigation,composition transportation during metasomatism and scanning line of elements,the paper considers its origion as a geologcal self-organization process. The streaked magnititite is a kind of special skarn which is usually associated with rhythmic lamiated beddings and the mine mineralizations of iron,copper,turgsten and tine.It is also called Wrigglite by some geologist in the world.The author uses system engineering theory to study the geochemical system of magnititite.According to the model of supersat- uration—form of nucleus—precipitation suggested by P.J.Ortoleva,the author considers the posssible chemical reaction mechanism is: X+A(?)Fe(3)O(4)—Y X+Y+A→CaF(2)+other mineral phases In the formula,X means iron chrorine,fluorine or boron complex which undergoes the reaction with carbonatite during transportation,A means carbonatite,Y means the primary product involving the infiltration reaction between A and X. It is obvious that the above schematic coupled reaction give rise to a negatve-feedback oscillation of nucleation-de- pletion—supersaturation cycle.