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东昆仑库德尔特金多金属矿床闪长玢岩年龄、地球化学特征及形成环境OA北大核心CSTPCD

Age,geochemistry and formation environment of diorite porphyrite in Kudeerte gold-polymetallic deposit,East Kunlun

中文摘要英文摘要

为厘定卡尔却卡矿田内的库德尔特金多金属矿床金矿成矿时代及其形成构造环境,对闪长玢岩进行了锆石U-Pb同位素测年和全岩地球化学研究.结果表明,闪长玢岩锆石U-Pb年龄加权平均值为 232.6±1.0 Ma(MSWD=0.17),略晚于赋存金矿的花岗闪长岩年龄(244~234.1 Ma)和金矿化绢云母Ar-Ar坪年龄(236.7±4.0 Ma),限定金成矿上限年龄不晚于 233 Ma.闪长玢岩SiO2 含量为 54.96%~55.57%,富Al(Al2O3 含量为 17.94%~18.07%),高Sr(455×10-6~505×10-6),低Y(19.2×10-6~26.4×10-6)和Yb(2.18×10-6~2.95×10-6),A/CNK值为 0.87~0.89,属高钾钙碱性准铝质系列.岩石轻、重稀土元素分馏较明显,轻稀土元素富集,LREE/HREE值为 6.24~8.69,(La/Yb)N值为 7.25~10.36,Eu中等亏损,富集大离子亲石元素(Rb、Th、U、K等),亏损高场强元素(Nb、Ta、P、Ti等),具有较高 Sr/Yb值(154.24~216.74)、Sr/Y值(17.23~24.27)、Nb/Ta值(17.79~20.05)和Mg#值(49.35~50.18),Rb/Sr值(0.27~0.36)介于 0.05~0.5 之间.综合区域地质背景与成矿特点认为,闪长玢岩形成于俯冲-碰撞转换构造阶段幔源岩浆底侵中元古代下地壳的局部熔融,中晚三叠世俯冲-碰撞转换时期,东昆仑地区受俯冲板片断离影响处于伸展环境,与典型挤压造山带具有明显差异,强烈壳-幔相互作用促进了区内矿床的集中产出.

In order to determine the metallogenic age and tectonic environment of the Kudeerte gold-polymetallic deposit in Kaerqueka ore field,this work studies on zircon U-Pb isotopic dating and whole rock geochemical analysis of diorite porphyrite.The results indicated that the zircon U-Pb weighted average age of diorite porphyrite is 232.6±1 Ma(MSWD=0.17),which is slightly later than the granodiorite age(244~234.1 Ma)and Ar-Ar plateau age(236.7±4.0 Ma)of gold mineralization sericite,limiting the upper age of gold mineralization to no later than 233 Ma.The dioritie porphyrite has SiO2 ranges from 54.96%to 55.57%,rich in Al(17.94%to 18.07%,Al2O3),and high in Sr(455×10-6~505×10-6),low Y(19.2×10-6~26.4×10-6)and Yb(2.18×10-6~2.95×10-6).A/CNK ratios range from 0.87 to 0.89,and belong to high potassium calc-alkaline sub-aluminum series.The fractionation of light and high rare earth elements(LREEs and HREEs)is obvious,and the LREEs are enriched.The LREE/HREE ratios range from 6.24 to 8.69,and the(La/Yb)N ratios from 7.25 to 10.36,and the Eu is medium deficit.Enrichment of large-ion lithophile elements(LILEs),such as Rb,Th,U,K,etc.,and depletion of high-field strength elements(HFSEs),such as Nb,Ta,P and Ti.It has high Sr/Yb ratios of 154.24 to 216.74,Sr/Y ratios of 17.23 to 24.27,Nb/Ta ratios of 17.79 to 20.05,Mg#values of 49.35 to 50.18,and Rb/Sr ratios of 0.27 to 0.3,in the range of 0.05 to 0.5.Based on the regional geological background and metallogenic characteristics,it is believed that the diorite porphyrite was formed in the partial melting of the mesoproterozoic lower crust during the subduction-collision transition tectonic stage of mantle source magma,and the East Kunlun area was in an extended environment influenced by subduction plate fragmentation during the Middle-Late Triassic subduction-collision transition,which is obviously different from the typical compressional orogenic belt.The strong crust-mantle interaction promotes the concentrated production of deposits in the area.

刘光莲;汪周鑫;张大明;张勇;刘智刚;马忠元

青海省第三地质勘查院,青海西宁 810029河北地质大学地球科学学院,河北石家庄 050031

地质学

年代学地球化学构造环境闪长玢岩库德尔特金多金属矿床东昆仑

chronologygeochemistrytectonic settingdiorite porphyriteKudeertegold-polymetallic depositEastern Kunlun

《地质通报》 2024 (007)

1133-1148 / 16

科技部国家重点研发计划项目课题《热液型矿床钴成矿作用与找矿勘查》(编号:2022YFC2903503)、国家自然科学基金重大研究计划项目《柴北缘花岗伟晶岩型锂铍等关键金属超常富集成矿的可能机制》(编号:92062217)和青海省"高端创新创业人才"计划项目《青海省东昆仑地区榴辉岩与成矿耦合关系研究》(编号:青地矿科[2021]61号)

10.12097/gbc.2022.10.027

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