滇西小龙潭矿区始新世岩浆岩的成因及其地质意义

发布时间：2018-05-16 11:05

本文选题：云南小龙潭 + 始新世　；参考：《成都理工大学学报(自然科学版)》2017年03期

【摘要】：云南省宾川县小龙潭矿区是一个大型斑岩型铜多金属矿床,铜矿体主要产于斑岩体及其外围接触带,矿化与斑岩体密切相关。对矿区主要侵入岩开展全岩地球化学、锆石LA-ICPMS U-Pb年代学和Hf同位素研究,获得含矿二长斑岩的~(206)Pb/~(238)U加权平均年龄为(35.98±0.16)Ma,属于始新世岩浆活动的产物。斑岩体SiO_2质量分数变化较大(64.81%~69.6%),高钾(4.36%~10.95%)和碱(Na_2O+K_2O8%),A/CNK为0.99~1.36,属高钾的碱性—过碱性、准铝质—过铝质斑岩;富集大离子亲石元素(K、Rb、Ba、Sr等)、亏损高场强元素(Ta、Nb、P、Ti等),富集轻稀土元素、亏损重稀土元素;虽被划入富碱侵入岩及A型花岗岩,但具C型埃达克岩地球化学特征。斑岩体锆石ε_(Hf)(t)值为-26.93~1.66,地壳模式年龄为1 009~4141 Ma,显示斑岩体来源于下地壳物质的部分熔融,并有幔源物质的加入。结合区域演化特征,认为小龙潭斑岩体形成于造山期后的拉张环境,陆陆碰撞挤压后应力松弛,岩浆沿断裂及次级断裂上侵,进而形成铜多金属矿床。
[Abstract]:Xiaolongtan deposit in Binchuan County Yunnan Province is a large porphyry copper polymetallic deposit in which the orebody mainly occurs in the porphyry and its peripheral contact zone and the mineralization is closely related to the porphyry. The whole rock geochemistry, zircon LA-ICPMS U-Pb geochronology and HF isotopic study of the major intrusive rocks in the ore area have been carried out. The weighted average age of 238U of the ore-bearing monzonitic porphyry is 35.98 卤0.16 Ma, which belongs to the product of Eocene magmatic activity. The SiO_2 mass fraction of the porphyry body varies greatly (64.81%), and the content of high potassium is 4.36% (10.95%).) and Na2O K2O8% of the alkaline-peraluminous porphyry is 0.991.36, which belongs to high-potassium alkaline-pericalcitic, quasi-alumina-peraluminous porphyry, and is rich in large ion lithophile element, such as KRbLi-Ba-Sr and so on, and it is depleted of the high field strength element, TaNbPnPnti, etc., and is enriched with light rare earth elements. Depleted heavy rare earth elements; although classified as alkali-rich intrusive rocks and A-type granites, they have geochemical characteristics of C type adakite. The zircon 蔚 ~ (-1) of the porphyry is -26.93 ~ 1.66, and the crustal model age is 1 009 ~ 4141 Ma. it shows that the porphyry originated from the partial melting of the lower crustal material with the addition of mantle material. Combined with the regional evolution characteristics, it is considered that the Xiaolongtan porphyry was formed in the post-orogenic extensional environment, the stress relaxation after continental collision, the magma transgression along the faults and secondary faults, and the formation of copper polymetallic deposits.
【作者单位】：中国地质大学地球科学与资源学院;地球系统科学延世大学;
【基金】：云南有色地质局综合研究项目(201307)
【分类号】：P588.1;P618.2

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