杂多地区喜山期花岗斑岩地球化学特征及地质意义

摘要

杂多地区花岗斑岩的麦多拉和纳日贡玛等岩体,测年结果显示年龄值分布为(40.8士0.4)Ma、(43.3士0.5)Ma,为喜山期的产物,杂多地区岩体是同一时代的产物.杂多地区多金属成矿带,包括纳日贡玛—麦多拉—乌葱察别—迪拉亿—哼赛青等斑岩型铜、铅、锌、钼、金、银等多金属矿床,微量元素(包括稀土元素),研究结果表明含矿斑岩和共生的钾质斑岩岩体在时空上具一致性,岩石化学成分均富碱(w(K2O)+w(Na2O)＞5％),高K和w (K2O)/w(Na2O)值远大于1, 微量元素富集Sr、Ba等大离子亲石元素和轻稀土元素等,均显示出钾玄岩和高钾系列岩石的特征,暗示杂多地区多金属成矿带的含矿斑岩属于典型的钾玄岩和高钾系列的斑岩.%The age of Maiduola granit-porphyry and Narigongma lithsomes, is the value of (40. 86±0. 4) Ma, (43. 3±0. 5) Ma. and they are the product of the early Stage of Yanshan, through the LAICP-M S zircon U-Pb isotopic dating, which indicate that many parts of the complex product of the times is the same lithsomes, the multi-metallic deposits of Cu, Mo, Pb, Zn, Au and Ag etc. of the porphyry types and trace elements (include REE) are found from narigongma, maiduola, yucongeongchabie, dilayi and hengsaiqing copper ore belt in the Eastern Tibet. The analytical results show that the ore-bearing porphyry and coexisting potassic plutons rocks, volcanic rocks and plutons have the same temporal-spatial distribution, uniform in the petrochemical compositions with alkali-rich (a; (K2O+NazO) >5%), high potassium and w (KZO) /w (Na2O) >1, and a strong enrichment in LILE of Sr, Ba etc and LREE. This shows the characteristics of the shoshonitic series rocks, indicating the ore-bearing porphyry of the