摘要
为了探讨花岗岩与风化壳型稀土矿形成关系,本文对桂东南十万大山—大容山花岗岩的年代学、岩石地球化学以及稀土矿物学进行了系统的研究。研究结果表明:两个代表性花岗岩样品分别给出了253±2 Ma和252±1 Ma的形成年龄,表明花岗岩形成于晚二叠世。花岗岩具有高钾、富铝、贫钛和贫镁的特征,属于典型的过铝质高钾钙碱性岩石,其地球化学特征与S型花岗岩非常相似。样品总体富集Rb、Th、U,相对亏损Ba、Nb、Sr、P和Ti等元素,其轻稀土元素(LREE)相对富集,重稀土元素(HREE)相对亏损,Eu负异常明显。综合分析表明,桂东南十万大山—大容山花岗岩来自古老地壳砂质岩的部分熔融,且在岩浆演化过程中发生了矿物(如磷灰石、斜长石等)的分离结晶作用。花岗岩样品中广泛含有独居石、磷钇矿、磷灰石和锆石等富稀土矿物,其中,独居石的化学成分中稀土氧化物总量达60%,磷钇矿的化学成分中稀土氧化物总量达55%。这些富含稀土元素的矿物组成与华南地区一些典型的风化壳型稀土矿成矿母岩相似,暗示桂东南晚二叠世花岗岩具有形成风化壳型稀土矿的潜力。
In order to reveal the relationship between Late Permian granite and regolith-hosted REE deposits,this paper conducts detailed studies on the geochronology,geochemistry,and rare earth mineralogy of the Late Permian granite in the Shiwandashan-Darongshan region of Southeast Guangxi.The results show that two representative granite samples yield formation ages of 253±2 Ma and 252±1 Ma,respectively,indicating that the granite formed in the Late Permian.These granites are characterized by high potassium and aluminum contents,along with relatively low titanium and magnesium contents,aligning with the features of aluminous high-potassium calc-alkaline rocks.In terms of geochemical affinity,they resemble S-type granite,being enriched in Rb,Th,U while relatively depleted in Ba,Nb,Sr,P,and Ti.Additionally,they have high contents of light rare earth elements(LREE)and low contents of heavy rare earth elements(HREE),accompanied by notable negative Eu anomalies.Comprehensive analysis indicates that these granites originated from partial melting of sandy rocks,with fractional crystallization of some minerals(such as apatite,plagioclase,etc.)occurring during the magmatic evolution process.The granite samples contain rare earth minerals such as monazite,xenotime,apatite and zircon.Notably,monazite and xenotime are rich in rare earth elements,with total rare earth oxides contents of 60% and 55%,respectively.The compositions of these rare earth minerals are comparable to those of parent rocks from typical regolith-hosted REE deposits in South China,suggesting that the Late Permian granite in Southeast Guangxi has the potential to form regolith-hosted REE deposits.
作者
杨栎娅
周云
付伟
刘耀辉
李政林
陈国玉
蔡永丰
Yang Liya;Zhou Yun;Fu Wei;Liu Yaohui;Li Zhenglin;Chen Guoyu;Cai Yongfeng(Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration,Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resources,Guangxi Science Innovation Base for Formation and Exploration of Strategic Critical Mineral Resources,Guilin University of Technology,Guilin,Guangxi 541004;China Nonferrous Mineral(Guilin)Geology and Mining Co.Ltd.,Guilin,Guangxi 541004)
出处
《地质科学》
北大核心
2025年第3期890-909,共20页
Chinese Journal of Geology(Scientia Geologica Sinica)
基金
国家自然科学基金项目(编号:42372102)
广西自然科学基金项目(编号:2022GXNSFAA035620)
广西重点研发计划项目(编号:桂科AB22035045)资助。
