地学前缘 ›› 2023, Vol. 30 ›› Issue (2): 415-425.DOI: 10.13745/j.esf.sf.2022.2.79

• 成藏-成矿作用与评价 • 上一篇    下一篇

浙闽边界碱性交代作用与稀土矿成矿关系研究进展

陈世忠1,2(), 周延1, 邢光福1, 徐敏成1,*(), 范飞鹏1, 隰弯弯1, 朱筱婷1, 郭维民1   

  1. 1.中国地质调查局 南京地质调查中心, 江苏 南京 210016
    2.中国地质调查局 乌鲁木齐自然资源综合调查中心, 新疆 乌鲁木齐 830026
  • 收稿日期:2021-01-05 修回日期:2022-05-09 出版日期:2023-03-25 发布日期:2023-01-05
  • 通讯作者: 徐敏成
  • 作者简介:陈世忠(1967—),男,博士,研究员,教授级高级工程师,地质学、岩石学矿物学矿床学专业, 现从事地质矿产调查研究工作。E-mail: nanjingcsz@qq.com
  • 基金资助:
    国家科技部重大研发计划项目(2016YFC0600210);中国地质调查局项目(ZD20220229);中国地质调查局项目(DD20160037);中国地质调查局项目(DD20190153);中国地质调查局项目(12120114002601);中国地质调查局项目(1212011120882)

Relationship between the large scale fenitization and REE mineralization on the border between Zhejiang and Fujian provinces: A review of recent research progress

CHEN Shizhong1,2(), ZHOU Yan1, XING Guangfu1, XU Mincheng1,*(), FAN Feipeng1, XI Wanwan1, ZHU Xiaoting1, GUO Weimin1   

  1. 1. Nanjing Center, China Geological Survey, Nanjing 210016, China
    2. ürümqi Comprehensive Survey Center on Natural Resources, China Geological Survey, ürümqi 830026, China
  • Received:2021-01-05 Revised:2022-05-09 Online:2023-03-25 Published:2023-01-05
  • Contact: XU Mincheng

摘要:

霓长岩化被认为是一种典型的岩浆期后碱性交代作用,与稀土矿化有关。霓长岩化有关的超大型稀土矿床的代表有白云鄂博稀土矿和川西牦牛坪稀土矿,它们是我国第一大和第二大轻稀土矿。福建政和铁山交代岩是华东最大的碱性交代岩,位于浙闽交界政和—大埔断裂带东北侧,区域预计稀土氧化物(REO)远景资源量可达6 211万吨。在铁山碱性交代岩中分布大面积的霓长岩,与P、REE、Ti、Ga等元素矿化关系密切。区域划分出3条霓长岩带,长度达1~2.3 km,宽度数百米,发现和评价了40余条磷灰石矿体,并富集稀土。霓长岩由长石、辉石、角闪石和黑云母等矿物组成。霓长岩中钾长石有4种形态:(1)面状分布,与黑云母、角闪石等的碱交代产物共生;(2)浅色钾长石脉;(3)深色钾长石脉;(4)和黑榴石共生。辉石呈现3种形式:(1)分布在深色角砾岩中; (2)零星分布在钾长石中;(3)与角闪石密切共生。霓辉石在镜下环带明显,中部浅绿色(淡绿色)到边部墨绿色(深绿色),说明核部透辉石成分多,边部霓石含量高。霓长岩形成于燕山期第二次(157~156 Ma)岩浆活动期,与南侧铜盆庵钾长花岗岩侵入活动有关,该期热液富集稀土元素。与燕山期第三次(118~114 Ma)岩浆活动有关的热液作用进一步产生碱性交代,并形成了一系列多金属矿化。

关键词: 浙闽边界, 铁山碱性交代岩, 霓长岩, 稀土矿

Abstract:

Fenitization is considered to be a typical post magmatic alkaline metasomatic process usually associated with REE mineralization. The typical super large REE deposits related to fenitization include the Bayan Obo REE deposit in Inner Mongolia and the Maoniuping REE deposit in western Sichuan as respectively the first and second largest LREE deposits in China. The Tieshan metasomatic rock (TMR), located on the northeastern side of the Zhenghe-Dapu fault zone on the border between Zhejiang and Fujian Provinces, is the largest potassic metasomatite in southeastern China. Its prospective rare earth oxide (REO) resource is expected to reach ~62 million tonnes, with porphyry copper and apatite deposits showing prospects for critical metals such as REEs. The widely occurring fenites in TMR are closely related to the mineralization of P, REE, Ti and Ga. The fenite belt is about 1-2 km long and hundreds of meters wide, where ~40 REE-rich apatite orebodies were discovered. The fenites are composed of feldspar, pyroxene, amphibole, biotite and melanite, etc. Among them, potassic feldspars occur in four modes: (1) in facial alkali alteration or in alkali alteration with melanites, (2) in light or (3) dark alkali feldspar veins, or (4) in association with black garnet. Pyroxenes has three occurrence modes: in breccias or feldspar, or in association with amphiboles. Aegirine pyroxene displays obvious girdle structure under the microscope, with a light-green core and dark green crust, indicating there are higher diopside components at the core and higher aegirine content at the edge. The fenite was formed in the second magmatic stage of the Yanshanian Movement (157-156 Ma) and probably related to the intrusion of the Tongpeng’an potassic feldspar granite to the east, as REEs were enriched during the magmatic-hydrothermal activity. In the third stage of the Yanshannian Movement (118-114 Ma), the Tieshan metasomatic rock was altered by alkaline hydrothermal fluid from the porphyries and polymetallic mineralization occurred.

Key words: border between Zhejiang and Fujian provinces, alkaline metasomatism, fenite, REE deposits

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