闽西南地区才溪岩体锆石SHRIMP定年及其地球化学特征  

Zircon SHRIMP age and geochemical characteristics of the Caixi pluton in southwestern Fujian Province

作　　者：赵希林[1] 毛建仁[1] 陈荣[1] 许乃政[1] 曾庆涛[1] 叶海敏[1] 

机构地区：[1]南京地质矿产研究所

出　　处：《岩石矿物学杂志》2007年第3期223-231,共9页Acta Petrologica et Mineralogica

基　　金：中国地质调查局基础地质调查项目(1212010611805;300313000070)

摘　　要：锆石SHRIMP年龄测试结果表明,闽西南地区才溪岩体的形成年龄为150±3Ma。才溪二长花岗岩富硅、富碱,弱过铝。岩石富集LREE,具Eu负异常,*Eu值为0.54~0.66,亏损Ba、Nb、Ta、Sr、P、Eu、Ti。(87Sr/86Sr)i值较高,为0.710462~0.712265,εNd(t)为-8.68^-9.81,t2DM为1.51~1.61Ga。岩石中黑云母富铝、镁,在Fe2+-Fe3+-Mg2+三角图上落入壳幔混源区。根据岩体地质学、地球化学特征,结合岩石学和矿物学特征认为,才溪二长花岗岩是由中元古代地壳物质熔融形成的壳源型花岗岩,在岩浆形成过程中有少量幔源物质的加入,形成于由挤压向伸展过渡的构造环境。Zircon SHRIMP results indicate that the Caixi pluton in southwest Fujian was formed at 150 ± 3 Ma. Caixi monzonitic granite is characterized by rich Si and alkali, weakly peraluminous nature, negative Eu （ ^＊ Eu≈ 0.54-0.66） anomalies, enrichment of LREE, and depletion of Ba, Nb, Ta, Sr, P, Eu, Ti. They are characterized by Sr-Nd isotopic composition with （^878r/^86Sr）i being 0. 710 462-0. 712 265, εNd（ t ） - 8.68- - 9.81 and t2Dm 1.51- 1.61 Ca. The biotite of rocks is characterized by rich Al, Mg, and belongs to the type of crustmantle mixed sources based on the triangle diagram of Fe^2 ＋ -Fe^3＋ -Mg^2＋. According to geochemical characteristics and petrological, mineralogical as well as geological data, it can be concluded that Caixi pluton belongs to the crust-source type granite formed by partial melting of the crust-derived rocks correlative to Proterozoic crust in the transformation from convergent to divergent tectonics. There were some materials mixed with the mantle materials in the process of rock formation.

关 键 词：才溪岩体 锆石SHRIMP年龄 地球化学特征 构造环境 闽西南 

分 类 号：P588.121[天文地球—岩石学] P597.3[天文地球—地质学]