云南易门狮子山铜矿基性侵入岩地球化学特征及其地质意义
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摘要
针对云南易门狮子山铜矿区基性侵入岩体(以矿区1237m中段层状辉长岩为例)的岩石学和地球化学特征分析,结果表明:SiO2,Na2O和K2O的平均质量分数分别为47.06%,3.91%,2.17%,σ(里特曼指数)平均为9.9;微量元素表现为大离子亲石元素K,Rb,Th明显富集,Sr,Ta,Nb,Yb,Cr,Y等元素亏损,显示了大陆裂谷玄武岩的特征;稀土元素总量为178.60×10-6~404.50×10-6,Eu负异常不明显(0.73~0.97),轻稀土元素富集(LREE/HREE=7.05~16.59,(La/Yb)N=6.56~36.94);研究还认为狮子山基性侵入岩是在大陆初始裂谷背景下形成的,属于深源玄武质岩浆演化形成,可能有壳源物质的混入。
Shizishan Copper deposit is a typical deposit occurred in the Kunyang rift of the Proterozoic Yangtze continent.In the ore district,layered basic intrusive rock bodies of gabbro intruded into the surrounding country rock.It was revealed that the average concentration of SiO2,Na2O and K2O of the intrusive rocks are 47.06%,3.91%,2.17%,and the average concentration of σ is 9.9.Trace elements of K,Rb,Th were enriched and Sr,Nb,Yb,Cr,Y were depleted,similar to the intra-continental rift basalts.Total REE ranges from 178.60 ×10-6 to 404.50×10-6 with no pronounced Eu negative anomaly(δEu=0.73~0.97)and with LREE enrichment(LREE/HREE=7.05~16.59,(La/Yb)N=6.56~36.94).Based on the study of geology,petrology and petrogeochemistry,it was considered that the basic intrusive rock bodies formed in initial continental rift environment and resulted from the deep source of formation of basaltic magma,mixed with crustal material.
Shizishan Copper deposit is a typical deposit occurred in the Kunyang rift of the Proterozoic Yangtze continent.In the ore district,layered basic intrusive rock bodies of gabbro intruded into the surrounding country rock.It was revealed that the average concentration of SiO2,Na2O and K2O of the intrusive rocks are 47.06%,3.91%,2.17%,and the average concentration of σ is 9.9.Trace elements of K,Rb,Th were enriched and Sr,Nb,Yb,Cr,Y were depleted,similar to the intra-continental rift basalts.Total REE ranges from 178.60 ×10-6 to 404.50×10-6 with no pronounced Eu negative anomaly(δEu=0.73~0.97)and with LREE enrichment(LREE/HREE=7.05~16.59,(La/Yb)N=6.56~36.94).Based on the study of geology,petrology and petrogeochemistry,it was considered that the basic intrusive rock bodies formed in initial continental rift environment and resulted from the deep source of formation of basaltic magma,mixed with crustal material.
引文
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[2]龚琳,何毅特,陈天佑.云南东川元古代裂谷型铜矿[M].北京:冶金工业出版社,1996.
[3]黎彤,饶纪龙.中国岩浆岩的平均化学成分[J].地质学报,1963.
[4]Wilson.Igneous petrofenesis[M].London:Allen and Unwin,1989.
[5]Irvine T N,Baragar WR A.Aguide to the chemical classification of the common volcanic rocks[J].Canad Earth sci.,1971,8:523-548.
[6]Pearce J A,Norry MJ.Petrogenetic implications of Ti,Zr,Y and Nb variations in volcanic rocks[M].Contrib Mineral Petrol,1979,69:33-47.
[7]Pearce J A,Harris N B W,Tindle A G.Tracelement discrimination diagrams for t he tectonic interpretation of granitic-rocks[J].J Petrol,1984,25:956-983.
[8]汪云亮,李巨初.幔源岩浆岩源区成分判别原理与峨眉山地幔源区性质[J].地质学报,1993,67(1):52-62.
[9]汪云亮,张成江.玄武岩类形成的大地构造环境的Ta/Hf-Th/Hf图解判别[J].岩石学报,2001,17(3):414-418.
[10]靳松,张利.浙闽地区新元古代变火山岩系岩石地球化学特征及其地质意义[J].矿物岩石,2008,28(1):101-103.
[11]云南省丽江-宾川地区二叠纪玄武岩地球化学特征及其构造背景研究[J].矿物岩石,2008,28(1):68-70.
[12]Pearce J A.Role of the sub-continental lithosphere in magma genesis at active continental margins[A].In:Hawkesworth C J,Norry MJ eds.Continental Basalts and Mantle Xenoliths[C].Shiva,Nantwich,1983,230-249.
[13]Tayloy S R,Mclennan S M.The continental crust:its compositiomand evolution[M].Oxford:Blackie,1985.
[14]吴利仁.论中国基性超基性岩成矿专属性[J].地质科学,1963.
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