投稿时间：2025-01-09
修订日期：2025-04-02
网络发布日期：2025-07-01
中文摘要:微山碱性岩-碳酸岩型稀土矿位于华北克拉通东部的鲁西地块，是中国第三大轻稀土矿床。为探究微山稀土矿碱性杂岩体岩浆演化与稀土成矿间的关系，文章对碱性杂岩体进行岩相学、地球化学和锆石U-Pb年代学分析工作。结果表明，该区岩体可分为碱性花岗岩、石英钠长斑岩、含霓辉石英正长岩和石英钾长斑岩，4类岩石均具有相似的地球化学特征，归属于碱性岩石，表现出富水、富CO32-，并且轻重稀土元素明显分馏的特点，晚期的石英钾长斑岩高度富集轻稀土元素。碱性花岗岩和石英钾长斑岩中的岩浆锆石年龄分别为（124.97±0.71）Ma（MSWD=1.7）和（124.73±0.93）Ma（MSWD=0.41），二者年龄相近且与前人报道的稀土成矿年龄（119±1.4）Ma具有继承关系，表明碱性杂岩体与稀土成矿存在成因联系。4类碱性岩石地球化学特征表明岩浆演化过程中氧逸度不断升高，钠质、CO32-等成分不断增加，稀土元素富集程度几何倍增。综上所述，富CO2的碱性岩浆经历高程度结晶分异作用、岩浆氧逸度升高、CO32-和钠质含量的富集，是形成碱性岩-碳酸岩型稀土矿的重要地质过程，为该类型稀土矿床的找矿勘探提供了重要岩石和地球化学指标。
Abstract:The Weishan rare earth deposit, located in the eastern part of the North China Craton within the Luxi Block, is the third-largest alkaline rock-carbonatite-type light rare earth deposit in China. To explore the relationship between the magmatic evolution of alkaline intrusive complex and rare earth mineralization in the Weishan deposit, petrographic, geochemical, and zircon U-Pb dating analyses were performed on the alkaline intrusions. The results indicate that the intrusions in this region can be classified into four main rock types: Alkaline granite, quartz-albite porphyry, aegirine augite-bearing quartz syenite, and quartz-potassium feldspar porphyry. These rocks all exhibit similar geochemical characteristics and are classified as alkaline rocks. They are characterized by high water content, enrichment in CO32-, and distinct fractionation of light and heavy rare earth elements, with late-stage quartz-potassium feldspar porphyry showing significant enrichment in light rare earth elements. Zircon U-Pb ages for alkaline granite and quartz-potassium feldspar porphyry are（124.97±0.71）Ma（MSWD=1.7）and（124.73±0.93）Ma（MSWD=0.41）, respectively. These ages are closely similar and are consistent with previously reported rare earth mineralization ages ((119±1.4)Ma), suggesting a genetic relationship between the alkaline intrusions and rare earth mineralization. Geochemical features of the four alkaline rock types indicate that during magmatic evolution, oxygen fugacity steadily increased, leading to an enrichment of sodium components, CO32-, and other elements. This resulted in a dramatic increase in the mobility and enrichment of rare earth elements. In conclusion, the formation of alkaline rock-carbonatite-type rare earth deposits is closely linked to high-degree crystallization differentiation, increased oxygen fugacity, and the accumulation of CO32- and sodium components- in CO2-rich alkaline magmas. These processes represent critical geological factors for the formation of such deposits and provide important petrological and geochemical indicators for exploration.
keywords:alkaline intrusive complex zircon U-Pb dating oxygen fugacity rare earth enrichment Weishan rare earth deposit
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基金项目:本文得到国家自然科学基金委员会面上项目（编号：42273071）、山东省联合重点基金（编号：U22A20571）、陕西省杰出青年科学基金（编号：2024JC-JCQN-41）和中央高校基金（编号：300102272202）联合资助
引用文本：
胡紫龙,杨金昆,安茂国,支成龙,尚振,张瑶飞,赵家良,张海东,夏明哲.2025.微山稀土矿床碳酸盐化硅酸岩岩浆演化与稀土成矿关系探讨[J].矿床地质,44(3):597~616HU ZiLong,YANG JinKun,AN MaoGuo,ZHI ChengLong,SHANG Zhen,ZHANG YaoFei,ZHAO JiaLiang,ZHANG HaiDong,XIA MingZhe.2025.Relationship between magmatic evolution of carbonatized silicate rock and rare earth mineralization in Weishan rare earth deposit[J].Mineral Deposits44(3):597~616
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