成都理工大学学报（自然科学版）2017，Vol.44Issue(3)：334-349,16.DOI:10.3969/j.issn.1671-9727.2017.03.06
滇西小龙潭矿区始新世岩浆岩的成因及其地质意义
Petrogenesis and geological significance of the Eocene porphyry in the Xiaolongtan mining area of the western Yunnan, China
摘要
Abstract
The copper mineralization of Xiaolongtan porphyry type copper-polymetallic deposit in Midu County of Yunnan Province is closely related to the porphyry and the ore-bodies mainly occur in the porphyry and its outer hornfels zone.Study of bulk geochemistry,zircon U-Pb dating,and Hf isotopic composition of the porphyry in the mining area reveals that the zircon U-Pb age of porphyry samples is (35.98±0.16) Ma,representing a product of the Eocene magmatic activity.Geochemical characters of the porphyry show large variation in SiO2 (64.81％～69.6％),high in K2O (4.36％ ～ 10.95％) and Na2O+K2O (＞8％),with the ratio of A/CNK being 0.99～1.36,belonging to K-rich alkaline-peralkaline and metaluminous-peraluminous porphyry series.Trace element analysis shows that the porphyry is deplete in Ta,Nb,P,Ti and rich in K,Rb,Ba,Sr,similar to the features of C-adakite.The eHf (t) from the zircon is-26.93～ 1.66 and the model age is 1 009 ～ 4 141 Ma,suggesting that the Eocene porphyry are derived from the partial melting of the lower crust material,and associated with the addition of mantle source material.On the basis of regional geological evolution,it is considered that the porphyry is formed in an extensional setting of post collision.After the compression of continental collision,the stress relaxation leads to the magma intrusion along the faults and secondary faults,and forms the copper polymetallic deposits.关键词
云南小龙潭/始新世/斑岩/锆石U-Pb/LA-MC-ICP-MSKey words
Xiaolongtan/Eocene/porphyry/zircon U-Pb/LA-MC-ICP-MS分类
天文与地球科学引用本文复制引用
周洁,王根厚,张莉..滇西小龙潭矿区始新世岩浆岩的成因及其地质意义[J].成都理工大学学报（自然科学版）,2017,44(3):334-349,16.基金项目
云南有色地质局综合研究项目(201307). （201307）
