青海省都兰县双庆铁矿床地球化学特征及成因意义

Rock and Ore Geochemistry Characteristics and Genetic Significance of the Shuangqing Iron in Dulan Area,Deposit in Qinghai Province

青海省祁漫塔格—都兰成矿带是以铁铜多金属为主的成矿带,其矿产丰富但研究程度较低。双庆铁矿床是该成矿带上十分典型的矿床,目前尚没有开展过系统的地球化学研究。本文采用ICAP6300全谱仪和Axios X荧光仪分析了全岩和矿石的主量元素,采用等离子体质谱仪分析了全岩和矿石的稀土元素含量,以期为弄清矿床成因提供地球化学证据。测试结果显示,不同类型的岩石主量元素含量差异甚大,稀土元素总体较高、负Eu异常,且LREE/HREE值为8.6,LaN/YbN为9.72,显示明显的LREE富集、HREE亏损的右倾斜配分型式。矿石以块状构造为主(TFeO为80.86%),次为块状与稠密浸染状构造(TFeO为56.12%),其平均LREE/HREE值为6.25,LaN/YbN为6.80,正Eu异常,低REE总量,表现为LREE富集、HREE亏损的向右倾斜配分型式。

This paper investigated the major elements and REEs in rocks and ores of the Shuangqing iron deposit in the Dulan area,Qinghai province.The results showed that different types of rocks varied greatly in their major elements contents,and that overall REEs showed a LREE enrichment and a HREE depletion of the fractionation pattern of right lean line.The average of LREE/HREE is 8.6 and the average of LaN/YbN is 9.72 indicated that LREE and HREE had undergone significant differentiation.In addition to one skarn sample,the granite and skarn rocks showed high REE contents and negative Eu anomalies,while marble samples exhibited low REE contents and positive Eu anomaly characteristic.The average content of total Fe2 O3 is 80.86 % for the massive structure ores;the average content of total Fe2O3is 56.12% for the time-massive structure and dense disseminated structure ores.The REE of all ores are enriched in LREE,HREE loss tilted to the right type of broken line fractionation pattern.The average LREE/HREE and the average LaN/YbN for ores are 6.25 and 6.80,respectively.All ores were characterized by low total REE contents and positive Eu anomalies.