德昌地区水系沉积物稀土氧化物总量地球化学特征及找矿方向  

Total rare-earth oxides in stream sediments in the Dechang area:Geochemical characteristics and prospecting targets

作　　者：朱友欢 聂飞[1] 邹佳作 李宏伟 周学铖 冉光辉 雷栋 ZHU You-Huan;NIE Fei;ZOU Jia-Zuo;LI Hong-Wei;ZHOU Xue-Cheng;RAN Guang-Hui;LEI Dong(Civil-Military Integration Center of China Geological Survey,China Geological Survey,Chengdu 610036,China)

机构地区：[1]中国地质调查局军民融合地质调查中心,四川成都610036

出　　处：《物探与化探》2025年第2期270-280,共11页Geophysical and Geochemical Exploration

基　　金：中国地质调查局项目“攀西冕宁—德昌地区稀土及多金属矿产地质调查”(DD20220965)。

摘　　要：川西冕宁—德昌地区是我国最重要的轻稀土成矿地带,为在德昌地区进一步寻求稀土资源找矿突破,对其开展了1∶5万水系沉积物测量。测试数据特征分析和化探异常提取结果表明稀土氧化物(REO)总量具有富集规律,且比较明显,元素异常与相关地质体空间分布叠合性较好。通过累积频率法、迭代法综合分析确定异常下限值,在此基础上编制元素异常图,并圈定5处主要异常区域。通过开展异常综合评价,优选出黄家坝、角坝村、一把伞和花椒园4个找矿靶区。通过成矿地质条件分析,采用赣南钻进行异常查证,在黄家坝找矿靶区发现3处轻稀土矿床,在角坝村找矿靶区发现2处重稀土矿床,在一把伞找矿靶区发现2处重稀土矿床,在花椒园找矿靶区发现2处重稀土矿床。研究认为,区内三叠纪黑云母钾长花岗岩和黑云母二长花岗岩为离子吸附型稀土矿成矿母岩,稀土主要在全风化层富集成矿。在德昌地区利用1∶5万水系沉积物测量,分析稀土氧化物总量地球化学特征,圈定的成矿远景区指示稀土元素富集于母岩;再根据富集地段表生条件,选择有利于风化壳形成、保存的地段快速圈定找矿靶区;实践证明,该思路是“内生外成”离子吸附型稀土矿简洁、有效的找矿模式。The Mianning-Dechang area in western Sichuan serves as the most important metallogenic belt of light rare earth elements(LREEs)in China.To make breakthroughs in the exploration of rare earth resources in the Dechang area,a 1∶50000 stream sediment survey was conducted in this study.The analysis of test data characteristics and the extraction of geochemical anomalies reveal that the total rare-earth oxides(REOs)in the area exhibit a pronounced enrichment pattern and that element anomalies largely overlap the spatial distribution of related geological bodies.Through comprehensive analysis using the cumulative frequency method and iterative method,this study determined the lower limits of anomalies and,accordingly,plotted element anomaly maps,with five main anomaly areas being delineated.The comprehensive evaluation of anomalies revealed four prospecting target areas:Huangjiaba,Jiaobacun,Yibasan,and Huajiaoyuan.The analysis of metallogenic geological conditions and the anomaly verification based on drilling in the Gannan area led to the discovery of three light rare earth deposits in the Huangjiaba prospecting target area,two heavy rare earth deposits in the Jiaobacun prospecting target area,two heavy rare earth deposits in the Yibasan prospecting target area,and two heavy rare earth deposits in the Huajiaoyuan prospecting target area.This study posits that the Triassic biotite moyite and biotite monzogranite in the study area are the metallogenic parent rocks of ion adsorption-type rare earth resources,with REEs primarily undergoing enrichment and mineralization in completely weathered layers.Therefore,a simple and effective prospecting pattern for"endogenous and exogenous"ion adsorption-type rare earth deposits in the Dechang area consists of analyzing the geochemical characteristics of the total REOs based on a 1∶50000 stream sediment survey,delineating metallogenic prospect areas that indicate parent rocks for REE enrichment,and selecting sections favorable for the formation and preservation of weathered crus

关 键 词：德昌 水系沉积物 稀土氧化物总量 地球化学 

分 类 号：P596[天文地球—地球化学]