贵州平坝县白云岩风化壳中稀土元素分布特征之初步研究

本文报道了平坝白云岩风化剖面风化前缘稀土元素超常规富集(总量达3%以上)现象及其特征,并通过主元素、稀土元素的测定,结合白云岩中“酸不溶物”的提取和代表性样品的化学淋溶实验研究,讨论了白云岩风化壳剖面稀土元素的分异特征,认为风化前缘稀土元素的富集是由3方面的因素共同作用造成的:1)对白云岩风化残积的继承;2)剖面上部一部分轻稀土淋滤聚积;3)碳酸盐岩中非均匀分布的原生含磷矿物风化产生的稀土磷酸盐矿物的聚集,后者是最重要的原因。

PRELIMINARY STUDY ON REE DISTRIBUTION CHARACTERISTICS IN DOLOMITITE WEATHERING PROFILE IN PINGBA COUNTY, GUIZHOU

This paper reported a super high concentration of REE occurred at the weathering frontier in dolomitite weathering profiles at Pingba, Guizhou Province. In order to understand the formation mechanism of the REE enriched bed and the fractionation between the REE, chemical leaching experiment and the extraction of the insoluble substance from dolomitite was made at room temperature on the base of the analysis of main elements and trace elements. It is believed that the super high concentration of REE at the weathering frontier was yielded by three factors: 1) an inheritance of residuum weathered by dolomite, 2) a leaching accumulation of some light rare earth elements from the upper part of profile, and 3) an accumulation of secondary mineral of rare earth phosphates formed by weathering of primary phosphor containing mineral distributed in dolomitite inhomogeneously, which was considered as the most important factor.