川西道孚县古鲁岩体岩石学及地球化学特征
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摘要
本文对川西道孚古鲁岩体进行了详细的野外调查并取样分析,岩体主要由英云闪长岩-花岗闪长岩组成,岩石中可见黑云母、角闪石等镁铁质矿物。地球化学分析结果表明:古鲁岩体的SiO_2含量在58.51%～66.46%之间,全碱含量在4.3%～6.22%之间,Al_2O_3含量变化于14.96%～15.75%之间,A/CNK值在0.83～0.97之间,ΣREE=162.38×10~(-6)～206.87×10~(-6),LREE/HREE=3.74～9.44,δEu=0.46～0.88;该岩体属钙碱性-高钾钙碱性准铝质中酸性侵入岩系列,具有I型花岗岩类特征,可能来源于下地壳物质的部分熔融,并混入少量幔源物质,为晚三叠世陆-陆碰撞引发的岩浆活动的产物。
The Gulu intrusion in Dawu,west Sichuan consists of tonalite-granodiorite.The study indicates that the Gulu intrusion contains 58.51-66.46% SiO_2,14.96-15.75% Al_2O_3 with total alkali of 4.3-6.22% and A/CNK value of 0.83-0.97,ΣREE of 162.38-206.87 ppm,LREE/HREE values of 3.74-9.44 and δEu value of0.46-0.88.The rock is characteristic of I type granitoid,belonging to calc-alkaline,metaluminous series.The magmatic material may be derived crust and partial melting mantle during continental collision in the Late Triassic.
The Gulu intrusion in Dawu,west Sichuan consists of tonalite-granodiorite.The study indicates that the Gulu intrusion contains 58.51-66.46% SiO_2,14.96-15.75% Al_2O_3 with total alkali of 4.3-6.22% and A/CNK value of 0.83-0.97,ΣREE of 162.38-206.87 ppm,LREE/HREE values of 3.74-9.44 and δEu value of0.46-0.88.The rock is characteristic of I type granitoid,belonging to calc-alkaline,metaluminous series.The magmatic material may be derived crust and partial melting mantle during continental collision in the Late Triassic.
引文
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[2]Middlemost,E.A.K.Naming materials in the magma/igneous rock system[J].Earth-Science Reviews,1994.37(3-4):215-224.
[3]Peccerillo,A.,S.R.Taylor.Geochemistry of eocene calc-alkaline volcanic rocks from the Kastamonu area,Northern Turkey[J].Contributions to Mineralogy and Petrology,1976.58(1):63-81.
[4]Maniar,P.D.,P.M.Piccoli.Tectonic discrimination of granitoids[J].Geological Society of America Bulletin,1989.101(5):635-643.
[5]Sun,S.S.,W.F.Mcdonough.Chemical and isotopic systematics of oceanic basalts:implications for mantle composition and processes[J].Geological Society London Special Publications,1989.42(1):313-345.
[6]Rapp,R.P.,E.B.Watson.Dehydration Melting of Metabasalt at 8-32 kbar:Implications for Continental Growth and Crust-Mantle Recycling[J].Journal of Petrology,1995.36(4):891-931.
[7]许志琴,侯立玮,王宗秀,等.中国松潘-甘孜造山带的造山过程[M].北京:地质出版社,1992,1-190.
[8]Pearce,J.A.,N.B.W.Harris,A.G.Tindle.Trace Element Discrimination Diagrams for the Tectonic Interpretation of Granitic Rocks[J].Journal of Petrology,1984.25(4):956-983.
[9]Pearce,J.Sources and Settings of Granitic Rocks[J].Episodes,1996.19(4):120-125.