Geochemical Characteristics and Genesis of Lamprophres in Gejiu Tin Deposit, Yunnan Province, China
详细信息
- 责任者：Cao Huawen (School of Earth Sciences and Resources ; China University of Geosciences ; Beijing 100083 ; China) ; Zhang Shouting
- 刊名：Geochimica
- 出版年：2013
- 卷期：42(4)
- 关键词：煌斑岩 ; lamprophyres ; 云南 ; Yunnan Province
- 页码：p.340-351
- 图表：illus., 3 tables, 26 refs.
- 分类号：0801
- issnNo：ISSN0379-1726
- isbnNo：CN44-1398/P
摘要
There are many altered lamprophyre veins,consisting of olive,pyroxene,biotite and plagioclase,in the strata of the east part of the Gejiu-Laochang Sn polymetallic belt.In geochemical composition,the SiO2 content is 51.54%-59.20%,K2O/Na2O value is 2.32-3.56,belonging to alkaline-subalkaline series,and potassic-calc alkaline type.K,Rb,Ba(LILEs) and light rare earth elements(LREEs) are relatively enriched,Sr is relatively weak depleted;Ta,Nb,P,Zr,Hf,Ti(HFSEs) are relatively depleted,with Ta,Nb and Ti negative anomalies;Cr,Co and Ni(transition element) are relatively depleted,indicating the compositions of mantle source in the subduction zone.∑REE is 480-1060 μg/g,mostly at 500 μg/g,LREE/HREE values range between 1.30-7.68,whereas δEu between 0.58-0.78,with negative Eu anomaly.The petrographical and geochemical characteristics indicate that the lamprophyres are formed in an extensional post-collision setting,which originate from the source region of residual flake metasomatism with mantle wedge during the Triassic Pleao-tethys plate subduction,followed by partial melting and weak assimilation of crust materials during the magma ascending.
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