| 滇东地区下寒武统磷块岩、的次生变化及其形成机制 |
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| 引用本文：.1991.Secondary enrichment of phosphorite in eastern Yunnan and its formation mechanism[J].Mineral Deposits,10(2):179~186 |
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| 中文摘要:滇东地区磷块岩在表生条件下所发生的一系列变化，是受其表生地球化学制约的，本文讨论了次生磷块岩的形成问题。 |
| 中文关键词:风化磷块岩 次生磷灰石 表生地球化学 化学活性 晶胞参数 轻稀土富集型分布模式 水解 |
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| Secondary enrichment of phosphorite in eastern Yunnan and its formation mechanism |
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| Abstract:Secondary changes of phosphorite in eastern Yunnan are all restricted by the surface geochemical condition. Carbonate minerals are chemically more active than phosphate minerals．Based on ”the principle of restraint of chemical reaction” the author considers that the erosion of the former should take place prior to that of the latter, that is, the activity of carbonate minerals will prevent phosphate minerals from erosion. Porous structures speed up the erosion of the deposits. This results in the decrease in CaO/P2O5 ratio and the relative enrichment of phosphate minerals. It is only when carbonate minerals are all leached out and the pH of the natural water decreases to a certain value that phosphate minerals can be resolved. As a result, secondary phosphorite is formed,PO43- is dissociated from the solution, REE are relatively enriched, grade of phosphorite is lowered，and ores are impoverished. Ilite, formed by hydrolysis of volcanic ash，is the main clay mineral in weathering phosphorite. Aluminum in secondary phosphor-aluminate minerals such as brazilianite comes from illite whereas PO43- from phosphorite. |
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