云南永善长坪铁多金属矿矿床成因     

张红芬  贾奎  崔茂才  虞慧  戴家胜 《云南地质》2011,30(1):50-52

矿体赋存于上二叠统宣威组下段铝土质粉砂质泥岩中。赤铁矿为主,次为磁铁矿、菱铁矿等。矿体与底板围岩呈突变关系,赤铁矿化强烈。  相似文献   

水辐射分解促进铀矿床围岩赤铁矿化蚀变的实验研究     

闵茂中  吴俊奇  戚成云  周云生 《铀矿地质》1992,(1)

本文根据人工辐照含二价铁的水溶液实验结果,讨论水的辐射分解对铀矿床围岩红化蚀变的意义。铀矿床围岩中各种形式的水,当遭受辐射线长期辐照后,将发生辐射分解作用,析出许多自由基及其反应产物(H,H_3O~+,OH,HO_2,H_2,O_2,H_2O_2等),其最终结果是明显地增强周围介质的氧化性,这无论在氧化或弱还原条件下,都将使铀矿床围岩中广泛分布的二价铁氧化成三价铁,产生红化(赤铁矿化)围岩蚀变,利用这一原理可解释某些地质现象。  相似文献   

Textural re-equilibration,hydrothermal alteration and element redistribution in Fe-Ti oxide pods,Singhbhum Shear Zone,eastern India     

《Chemie der Erde / Geochemistry》2021,81(1):125679

This study describes textures and mineral chemistry of magnetite-ilmenite-bearing pods/pockets in mineralogically diverse feldspathic schist near Pathargora in the Singhbhum Shear Zone, eastern India. The textural and geochemical characteristics of the magnetite-ilmenite assemblage are the results of a protracted geological history involving magmatic crystallization and oxidation-exsolution of titanomagnetite, deformation-induced recrystallization and textural re-equilibration and hydrothermal fluid-induced hematitization of magmatic magnetite. The magnetite grains contain characteristic trellis and sandwich ilmenite lamella, which are interpreted to be the products of oxidation-exsolution of ulvöspinel component of magnetite-ulvöspinel solid solution. The exsolution process was accompanied by preferential partitioning of spinel elements such as Cr, Al and V in magnetite and Ti, Mn, Mg, HFS elements (Nb, Ta), transition elements (Sc, Co, Cu and Zn) and granitophile elements (Mo, Sn and W) in ilmenite. The deformed sandwich lamella is locally recrystallized and transformed into granular ilmenite close to fractures, micro-shear planes and magnetite grain boundaries. Coarse granules of ilmenite, within or associated with magnetite, are of two textural types: one invariably contains Fe-rich exsolved phase and may be of magmatic origin, while the other mostly formed by strain-induced, fluid-mediated expulsion (from the interior of magnetite to its boundary) and dynamic recrystallization of existing ilmenite lamella in magnetite, and dynamic recrystallization of primary ilmenite containing Fe-rich exsolved phases. Magnetite is variably hematitized. The highly porous nature and trace element geochemistry of hematite and mass-balance calculations suggest the hematitization was mostly redox-independent and was caused by infiltration of metal-rich, reduced and acidic fluid. The hematitization process was associated with significant enrichment and immobilization of U, Th, Pb, REEs, Cu, Mo and W and depletion of Ni, Cr, V in hematite.  相似文献