川西冕宁-德昌REE矿带风化型矿床的矿石类型及成因

川西冕宁-德昌REE矿带中的风化型矿石研究相对缺乏.根据近几年的野外地质调查，采用电子探针、X光粉晶衍射、全岩分析等对大陆槽、牦牛坪和木落寨矿床中疑似风化矿的样品进行类型和成因分析.结果表明:大陆槽风化型矿石中大量粘土矿物（达40%）和矿石矿物（达60%）发育，风化程度高；相反，牦牛坪和木落寨疑似风化型矿石中几乎没有粘土矿物，风化程度低.通过对牦牛坪和木落寨疑似风化型矿石进行地球化学特征、矿物组成分析并与围岩、矿脉的组成和产状对比，表明疑似风化型矿石主要是由矿脉和围岩在强烈的构造作用下发生机械风化形成.频繁的角砾构造使大陆槽矿石发生强烈的机械风化作用，并加速了矿石发生一定的水岩反应，促进矿石发生中等强度的化学风化作用.目前整个矿带中未发现明显的生物风化作用.整个稀土矿带的风化型矿石比南岭离子吸附型稀土矿石的风化程度低，形成时间较晚（11 Ma），氟碳铈矿大量保存，还没有形成离子吸附型矿床. 

Ore Types and Genesis of Weathered Deposits in Mianning-Dechang REE Ore Belt,Western Sichuan Province,Southwestern China

The study of weathered ores is relatively limited in the Mianning-Dechang REE ore belt, western Sichuan. According to the geological survey in recent years, ore types and genesis of suspected weathered ore from Dalucao, Maoniuping and Muluozhai deposits were studied through EPMA, XRD and whole rock analysis. The results show that a large number of clay minerals (up to 40%) and ore minerals (up to 60%) are developed in the weathered ore of the Dalucao deposit, and the weathering degree is relatively high. On the contrary, suspected weathered ore types almost have not developed clay minerals from Maoniuping and Muluozhai deposits, and the weathering degree is relatively low. Through the geochemical characteristics and mineral composition analysis of the suspected weathered ore in Maoniuping and Muluozhai deposits, combining the compositions and occurrences of the wall rock and veins, it is obvious that the suspected weathed ore has been formed by mainly mechanically weathering from the nearby veins and wall rock under the strong tectonic action. Frequent breccia activities promote the strong mechanically weathering of weathered ores, and accelerate the water-rock reaction in Dalucao deposit. At present, there is no obvious biological weathering in the ore belt. The weathered ores in the belt have lower weathering degree than that of the Nanling ion adsorption type rare earth elements ores, and the age of the formation of the belt is younger (11 Ma) and a large amount of bastnaesite preservation, so it has not formed the ion adsorption type deposit.