关于华北元古宙富钾、富稀土沉积岩是白云鄂博大型稀土矿床矿源层的讨论

Discussion on Proterozoic K- and REE-rich sedimentary rocks in North China as ore source of Bayan Obo rare earth deposits

文章对大连、北京元古宙沉积岩及白云鄂博稀土矿围岩的岩石化学成分、独居石形态和稀土元素特征等进行了分析与总结,结果显示三者特征相似。因此认为白云鄂博的稀土矿不是来自地幔岩而是源于大陆增生,华北元古宙富钾、富稀土沉积岩可能是白云鄂博巨型稀土矿的矿源层。文章还提出了一个白云鄂博稀土矿的理想大陆增生成矿模式图。

A new point of view is suggested in this paper which holds that the Proterozoic K- and REE-rich sedimentary rocks in North China might be the ore source of the huge Bayan Obo REE deposits in Inner Mongolia. And this can also serve as an example of continental accretion mineralization. The authors agree with Ji Kejie＇s ＂three-sources （i. e., ore source, water source and heat source） mineralization theory＂. A series of figures and tables given in this paper demonstrate that there exist similarities between Proterozoic sedimentary rocks in Beijing and Dalian and host rocks of the Bayan Obo REE deposits in Inner Mongolia in such aspects as monazite shapes, chemical compositions, and REE contents. Based on a comparison of chemical compositions and REE contents between Proterozoic sedimentary rocks as well as host rocks of the Bayan Obo deposits and ophiolite and chondrite, the authors consider that the Bayan Obo REE deposits must have resulted from continental accretion mineralization instead of being derived from the mantle. An idealized continental accretion mineralization model is put forward in this paper for the Bayan Obo deposits.