河北矾山燕山期侵入岩地球化学特征及成因  

GEOCHEMICAL CHARACTERISTICS AND GENESIS OF YANSHANIAN INTRUSIVE ROCKS IN FANSHAN, HEBEI PROVINCE

作　　者：王强[1] 许继锋[1] 赵振华[1] 王人镜[2] 熊小林[1] 

机构地区：[1]中国科学院广州地球化学研究所,广东广州510640 [2]中国地质大学,湖北武汉430074

出　　处：《矿物学报》2002年第2期160-168,共9页Acta Mineralogica Sinica

基　　金：国家攀登计划预选项目 (95 预 2 5) ;国家自然科学基金项目 (批准号 :4 0 172 0 2 8) ;中国科学院知识创新项目 (KZCX2 10 2 );国家重点基础研究发展规划项目 (G19990 4 32 0 2 ) ;广东省自然科学基金博士启动项目 (994 588)

摘　　要：河北矾山地区燕山期侵入岩可分为早、晚两期。早期 (中侏罗世 晚侏罗世 )侵入岩主要由二长闪长岩、石英二长闪长岩、石英二长岩、正长岩构成 ,以高钾钙碱性岩系列岩石为主 ;SiO2 =53 58%～ 60 57% ,Al2 O3=16 16%～ 17 2 3 % ,Na2 O +K2 O =5 76%～ 8 96% ,K2 O =2 2 5%～ 4 55% ,Na2 O/K2 O =1 14～ 1 56;ACNK =0 72～0 86,NKA =0 4 7～ 0 77;Eu /Eu =0 80～ 0 95,轻稀土富集 ,重稀土和Nb、Ta、Hf、Ti亏损 ,相对低Zr、Rb和Rb/Sr,但高Sr和Sr/Y ,具有埃达克质岩石的部分特征。晚期 (白垩纪 )侵入岩由碱长石英正长岩、石英正长岩、石英二长岩、碱长花岗岩、钾长花岗岩构成 ,以钾玄岩系列岩石为主 ;比早期岩石富SiO2 ,低Al2 O3、富Na2 O +K2 O和K2 O ,但低Na2 O/K2 O ;ACNK =0 82～ 1 0 7,NKA =0 77～ 0 92 ;Eu /Eu =0 65～ 1 0 0 ,轻稀土富集 ,重稀土和Nb、Ta、Hf、Ti亏损 ,相对高Zr、Rb和Rb/Sr,但低Sr和Sr/Y。矾山地区早期侵入岩的形成可能与伊泽奈崎(Izanaqi)板块向欧亚大陆板块的俯冲所导致的挤压增厚有关 ;晚期侵入岩可能形成于拉张环境中。The intrusive rocks of two (early and late) stages of the Yanshanian epoch have been recognized in the region of Fanshan, Hebei Province. The earlier stage intrusive rocks (Middle Jurassic Late Jurassic) are composed of monzodiorite, quartz monzodiorite, quartz monzonite and syenite, with SiO 2=53.58%～60.57%, Al 2O 3=16.16%～17.23 %, Na 2O+K 2O=5.76%～8.96 %, K 2O=2.25%～4.55%, Na 2O/K 2O=1.14～1.56 (the ratio of one sample is 0.96), ACNK=0.72～0.86, NKA=0.47～0.77; Eu */Eu =0.80～0.95, LREE enrichment, HREE and Nb, Ta, Hf and Ti depletion, relatively low Zr, Rb and Rb/Sr, but high content of Sr and high Sr/Y. The earlier stage intrusive rocks have many characteristics of adakitic rocks. However, the later stage (Cretaceous) intrusive rocks are composed of alkali feldspar quartz syenite, quartz synenite, quartz monzonite, alkali feldspar granite and K feldspar granite, with higher SiO 2, Na 2O+K 2O and K 2O, but lower Al 2O 3, Na 2O/K 2O than those of earlier stage intrusive rocks; ACNK=0.82～1.07, NKA=0.77～0.92; Eu */Eu =0.65～1.00, LREE enrichment, HREE and Nb, Ta, Hf and Ti depletion, higher Zr, Rb and Rb/Sr, but lower Sr and Sr/Y. The intrusive rocks of the earlier stage in Fanshan could be derived from a compressing and thickening tectonic setting (>40 km) related to the subduction of the Izanaqi plate into the Eurasian plate, while the later stage intrusive rocks could be formed in a somewhat extensional environment.

关 键 词：钾玄岩 埃达克质岩石 高钾钙碱性侵入岩 构造环境 地球化学 河北 

分 类 号：P588.12[天文地球—岩石学] P59[天文地球—地质学]