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高校地质学报 ›› 2019, Vol. 25 ›› Issue (6): 914-.DOI: 10.16108/j.issn1006-7493.2019027

• 其他学科 • 上一篇    下一篇

浙江临安石室寺NYF型伟晶岩中稀有稀土金属的矿物学行为与成矿过程

王吴梦雨,饶灿,董传万,林晓青,覃莉茜,吕青   

  1. 1. 浙江大学地球科学学院,杭州 310027;
    2. 中化地质矿山总局浙江地质勘查院,杭州 310002
  • 收稿日期:2019-03-28 修回日期:2019-04-08 出版日期:2019-12-20 发布日期:2020-01-06

Mineralogical Behavior andMetallogenic Process of Rare and Rare EarthMetals in Shishisi NYF-Type Pegmatite, Lin’an, Zhejiang Province

WANGWU Mengyu,RAO Can,DONG Chuanwan,LIN Xiaoqing,QIN Lixi,LYU Qing   

  1. 1.SchoolofEarthSciences,ZhejiangUniversity, Hangzhou 310027, China;
    2.ZhejiangGeologicalprospectingInstituteofCCGMB, Hangzhou 310002, China
  • Received:2019-03-28 Revised:2019-04-08 Online:2019-12-20 Published:2020-01-06

摘要: 浙江临安石室寺伟晶岩位于河桥岩体西北面,属于典型的Nb-Y-F (NYF) 型伟晶岩,富含大量稀有稀土矿物。本文在野外考察和显微镜观察的基础上,结合电子探针背散射电子图像观察与矿物化学成分分析,系统鉴定了石室寺NYF 型伟晶岩中的稀有稀土矿物,揭示了稀有稀土元素的富集、迁移、结晶与成矿过程。研究结果表明:(1) 石室寺伟晶岩中的稀有稀土矿物有铌钽矿物(铌铁矿、铌锰矿、重钽铁矿、细晶石等)、钇矿物(褐钇铌矿、黑稀金矿)、钨矿物(黑钨矿、
白钨矿、铌钨矿物)、铈矿物(独居石、氟铈矿、氟碳铈矿) 和钍矿物等。(2) 铌钨系列矿物的WO3含量在8.30~70.51 wt%之间呈规律变化,可能为铌铁矿与黑钨矿之间形成的一系列多体矿物。(3) 铌铁矿LA-ICP-MS U-Pb 定年结果显示,石室寺伟晶岩的形成年龄为133±2 Ma,与河桥花岗岩具有成因联系。(4) 石室寺NYF 型伟晶岩中稀有稀土元素的成矿过程与其岩浆的结晶演化密切相关:岩浆阶段,锆石、钍石与独居石等矿物最早晶出;岩浆—热液阶段,黑稀金矿、铌铁矿、褐钇铌矿、氟铈矿等稀有稀土矿物逐渐结晶;热液阶段,黑钨矿、铌钨矿物相继形成,同时早期的独居石、氟铈矿受晚期热液交代形成次生铈矿物。

关键词: NYF型伟晶岩, 稀有稀土矿物, 铌铁矿-黑钨矿多体系列, 铌铁矿U-Pb定年

Abstract: Shishisi pegmatite, a typical Nb-Y-F (NYF) type pegmatite with different kinds of rare and rare earth minerals, occurs in the northwest of Heqiao granite pluton, Lin’an county, Zhejiang Province. Based on field and microscopic observations, in combination with back-scattered electron (BSE) imaging and quantitative electron-microprobe technology (EMPA), the rare and rare earth minerals from Shishisi NYF-type pegmatite are systematically analyzed for the enrichment, migration, crystallization, and mineralization processes of rare and rare earth metal elements in this paper. The results show that (1) many rare and rare earth metal minerals in the Shishisi pegmatite are recognized including Nb-Ta oxide minerals (columbite, tapiolite, microlite etc.), Y-bearing minerals (fergusonite
and polycrase), W-bearing minerals (wolframite, scheelite and Nb-W-bearing minerals), Ce-bearing minerals (monazite, fluocerite and bastnaesite) and Th-bearing minerals. (2) The WO3 content ranges from 8.30 to 70.51 wt.% in Nb-W-bearing minerals, suggesting a series of polysomic minerals between columbite and wolframite. (3) LA-ICP-MS U-Pb dating of columbite-(Fe) from the Shishisi pegmatite yields an age of 133±2 Ma, indicating its genetic relationship with Heqiao granitic pluton. (4) The rare and rare earth elements mineralization processes in Shishisi NYF-type pegmatite were closely related to the crystallization and evolution of magma. During the magmatic stage, zircon, thorite and monazite were crystallized; polycrase, columbite, fergusonite and fluocerite were formed
in the magmatic-hydrothermal stage; wolframite and wolframoixiolite were crystallized in the hydrothermal stage. In the meantime, the early monazite and fluocerite were altered to secondary Ce-bearing minerals by late hydrothermal fluids.

Key words: NYF-type pegmatite, rare and rare earth minerals, polysomic minerals between columbite and wolframite, columbite U-Pb dating