摘要
北秦岭卢氏官坡地区龙潭沟-火炎沟锡矿床是近年来在豫西地区实现的重大找矿突破,然而前人对该矿床的形成时代以及成矿作用研究较少。本文以与锡成矿关系密切的白云母电气石钠长石花岗伟晶岩(以下称含锡花岗伟晶岩)为研究对象,开展了岩相学,岩石地球化学,以及锡石、铌钽铁矿和磷灰石LA-ICP-MS U-Pb年代学研究,探讨了花岗伟晶岩的源区性质、成岩成矿时代和构造环境。结果显示:(1)含锡花岗伟晶岩的锡石、铌钽铁矿和磷灰石U-Pb年龄分别为408.1±1.5Ma、391.5±2.0Ma和387.0±2.1Ma;锡石年龄代表早期锡矿化的时间,铌钽铁矿和磷灰石代表晚期铌钽矿化的时间;结合区域研究成果,认为官坡-丹凤地区存在两期锡铌钽等稀有金属成矿作用。(2)含锡花岗伟晶岩富硅和铝,贫碱,富集Rb、Cs、Nb、Ta和Hf,亏损Ba、P和Ti,相对富集重稀土元素,亏损轻稀土元素,具明显的Eu负异常,暗示其源岩应为陆壳物质。(3)龙潭沟-火炎沟锡矿床形成于造山后由挤压到伸展转换的构造背景。通过与秦岭造山带的灰池子复式岩体,以及成铀伟晶岩和稀有金属伟晶岩进行对比,我们认为,龙潭沟-火炎沟锡矿床的成锡伟晶岩地球化学特征既有相似性又有差异性,具更高的结晶分异演化程度;沉积源岩物质组成可能是龙潭沟-火炎沟伟晶岩成锡矿的关键。卢氏官坡地区龙潭沟-火炎沟锡矿床的发现,对于在昆仑-秦岭-大别地区找早泥盆世的稀有金属矿床,尤其是锡矿床,具有重要意义。
The newly discovered Longtangou-Huoyangou Sn deposit in the Lushi-Guanpo area of the North Qinling Orogeny is a major prospecting breakthrough in western Henan.However,the mineralization age and genesis of this deposit have not been studied yet.The petrography,petrogeochemistry and LA-ICP-MS U-Pb chronology of cassiterite and apatite related to Sn mineralization are studied on muscovite turmalite albitite granite-pegmatite,from which the following results are obtained:(1)The U-Pb ages of the cassiterite,columbite-tantalite and apatite are 408.1±1.5Ma,391.5±2.0Ma and 387.0±2.1Ma,respectively,representing the magma crystallization and early-stage Sn mineralization age and late-stage Nb-Ta mineralization age;and it also shows that there exist two stages of metallogenesis of rare metals in Guanpo-Danfeng area.(2)Geochemically,the rocks are rich in Si,Al,Rb,Cs,Nb,Ta and Hf,but deficient in Ba,P and Ti;and they have a low alkali content and∑HREE/∑LREE ratio(>1)with a negative Eu anomaly;and as a result,they belong to potassium-calc-alkaline rocks.(3)The Longtanggou-Huoyangou Sn deposit was formed in a tectonic environment of crust extension that transformed from the post-orogenic stage in the Early Devonian.By comparing the Huichizi complex granite,uranium pegmatite and rare metal pegmatite in the region,we think that the Longtangou-Huoyangou Sn deposits have similar geochemical characteristics,however,each keeps its specific properties,and they all have a higher degree of crystal differentiation;and their source rock composition may be the key to forming Sn deposit.The discovery of Longtanggou-Huoyangou Sn deposit is of great significance for searching the Early Devonian rare metal deposits,especially the Sn deposits,in the Kunlun-Qinling-Dabie area.
作者
刘新星
张娟
李肖龙
杨俊峰
王猛
王瑛雪
张晓艳
LIU XinXing;ZHANG Juan;LI XiaoLong;YANG JunFeng;WANG Meng;WANG YingXue;ZHANG XiaoYan(Hebei Key Laboratory of Strategic Critical Mineral Resources,Hebei GEO University,Shijiazhuang 050031,China;Henan Academy of Geology,Zhengzhou 450001,China)
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2023年第5期1484-1500,共17页
Acta Petrologica Sinica
基金
国家重点研发计划青年科学家项目(2021YFC2900100)
国家自然科学基金项目(41702352)
河北地质大学校内青年项目(QN202217)
河北地质大学2023年国家预研项目资助(008)联合资助.
