试论有机质在华南花岗岩风化壳REE溶出、迁移和富集中的作用

通过实验研究，论证了花岗岩风化壳中存在有机质，含有丰富的一元脂肪酸和二元脂肪酸，腐殖酸及多糖化合物。ＲＥＥ能以ＲＥ（Ｈ２Ｏ）配位离子从原岩溶出，一些有机介质和无机介质有助于ＲＥＥ从原岩溶出、迁移，其中以脂肪酸溶出量最高。溶出过程配位反应与水解反应同时出现，溶出和在风化壳中保留同时进行，反应受ｐＨ控制。风化壳中ＲＥＥ存在有机结合形态，可能与长链酸或腐殖酸关系比较密切。活性态ＲＥＥ除了与粘土矿物关系密切外，可能与多羟基化合物或多糖有关。

A PRELIMINARY STUDY ON THE ROLE OF ORGANIC MATTER IN DISSOLUTION, MIGRATION AND CONCENTRATION OF RARE EARTH ELEMENTS IN WEATHERING CRUST OF GRANITES FROM SOUTH CHINA

Experiments demonstrate that there exists organic matter in the weathering crust of granites.The organic matter mainly consists of mono-and di-carbonxylic acids,humic acids and polysaccharides.REE can be dissolved out of parent rocks in the complex form of REE(H2O).The presence of some kinds of matter,especially alphatic acids,may effectively accelerate the dissolution and migration of REE.Complexing reactions and normal hydrolysis,as well as dissolution and retention,coexist during weathering, controlled by pH value.There are REE-organic complexes,which are probably related to long chain fatty acids or humic acids,in the weathering crust. The rare earth elements in active state may bear close relations with polyhydroxy compounds or polysaccharides,as well as with clay minerals.