投稿时间：2020-11-04
修订日期：2021-01-17
网络发布日期：2021-10-22
中文摘要:在川南沐川地区发现了四川首例古风化壳-沉积型Nb-REE多金属矿，为了填补四川地区同类型矿产的研究空白和厘清沐川地区宣威组底部Nb-REE多金属矿的富集特征和成因机制，开展了野外实地调查、岩石地球化学等系统性研究，探讨其富集特征、物源和成因机制及与新生代攀西地区稀土矿床的成因联系。研究结果表明，川南沐川地区宣威组底部Nb-REE多金属富集层产于宣威组底部，厚度5.09~15.33 m，平均厚度10.10 m，w （Nb2O5）为37~909 μg/g，平均256 μg/g，稀土元素总量0.02%~1.55%，平均0.12%；下部紫红色铁质泥岩型Nb-REE多金属富集层的物源主要来源于峨眉山玄武岩，上部灰白色、浅灰绿色、灰色、深灰色泥岩型NbREE多金属富集层除了峨眉山玄武岩的剥蚀产物提供物源外，同时还有大量碱性火山灰的混入；Nb-REE多金属富集层中的稀土元素总量及铌元素含量总体上呈"先增加、再降低"的变化规律，稀土元素在紫红色铁质泥岩中的富集程度比铌元素高，铌、稀土元素含量变化曲线在上部的灰白色、浅灰绿色、灰色、深灰色泥岩中表现出"同增同减"的规律；沐川地区Nb-REE多金属富集层的成矿模式可分为峨眉山玄武岩喷溢阶段、风化富集阶段、沉积富集阶段和盖层沉积阶段4个阶段，成矿作用以风化淋滤和沉积作用为主。沐川地区晚二叠世Nb-REE成矿及新生代攀西地区稀土矿床与峨眉山地幔柱分别有着直接和间接的联系，研究两者的成因联系有利于拓展战略性关键矿产的找矿空间。
Abstract:The first paleoweathering crust-sedimentary Nb-REE polymetallic deposit was discovered in Muchuan area, southern Sichuan Province. In order to fill the research gap of the same type of mineral resources in Sichuan Province and clarify the enrichment characteristics and genetic mechanism of Nb-REE polymetallic deposit at the bottom of Xuanwei Formation in Muchuan area, field investigation and petrochemistry study were carried out to explore its enrichment characteristics, material source, genetic mechanism and its relationship with Cenozoic Panxi rare earth deposit. The results show that the Nb-REE polymetallic enrichment layer occurs at the bottom of the Xuanwei Formation in Muchuan area, with a thickness of 5.09~15.33 m, the average thickness is 10.10 m, the content of w(Nb2O5) is 37~909 μg/g with an average of 256 μg/g and the total amount of rare earth element is 0.02%~1.55% with an average of 0.12%. The source of the purplish red iron mudstone type Nb-REE polymetallic enrichment layer in the lower part is mainly from the Permian Emeishan basalt; the upper part is gray white, light gray green, gray, dark gray mudstone-type Nb-REE polymetallic enrichment layer, apart from the source from theweathering&erosion products of the Emeishan basalt, there is also a significant amount of alkaline volcanic ash. The total rare earth and niobium content in the Nb-REE polymetallic enrichment layer generally show the change rule of "first increase, then decrease". The enrichment degree of rare earth elements in the purplish red iron mudstone is higher than that of niobium, and the change curve of niobium and rare earth elements content in the upper part mudstone shows the rule of"increase together and decrease together". The metallogenic model of Nb-REE polymetallic enrichment layer in Muchuan area from early to late can be divided into four stages:Emeishan basalt eruption stage, weathering enrichment stage, sedimentary enrichment stage and cover deposition stage. The mineralization is dominated by weathering leaching and sedimentation. The Late Permian Nb-REE mineralization in Muchuan area is directly related to the Emeishan mantle plume, whereas the Cenozoic Panxi rare earth deposits are indirectly related to the Emeishan mantle plume. Study on the genetic relationship between the two types of REE mineralization is of benefit to expand the prospecting space of critical minerals.
keywords:geochemistry niobium rare earth element Xuanwei Formation enrichment characteristics genesis Muchuan
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基金项目:本文得到四川省自然资源厅省政府性投资地质勘查项目的资助
引用文本：
文俊,刘治成,竹合林,张航飞,张金元,钟海仁,陈东方,郭文彦,游学军,赵伟,凌茂前,李鹏程,何永刚,郭宇衡.2021.川南沐川地区上二叠统宣威组底部Nb-REE超常富集特征及其地质意义[J].矿床地质,40(5):1045~1071WEN Jun,LIU ZhiCheng,ZHU HeLin,ZHANG HangFei,ZHANG JinYuan,ZHONG HaiRen,CHEN DongFang,GUO WenYan,YOU XueJun,ZHAO Wei,LING MaoQian,LI PengCheng,HE YongGang,GUO YuHeng.2021.Characteristics and geological significance of abnormal enrichment of Nb-REE in bottom of Uper Permian Xuanwei Formation in Muchuan area, southern Sichuan[J].Mineral Deposits40(5):1045~1071
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