黑龙江饶河枕状玄武岩地质、地球化学特征及其构造属性  

Geological and geochemical characteristics of Raohe pillow basalts of Heilongjiang Province and its tectonic implication

作　　者：何松[1] 孙晓猛[1] 张旭庆[1] 万阔[1] 郑涵[1] 李多姿 HE Song SUN Xiao-meng ZHANG Xu-qing WAN Kuo ZHENG Han LI Duo-zi(College of Earth Sciences, Jilin University, Changchun 130061, China)

机构地区：[1]吉林大学地球科学学院,长春130061

出　　处：《世界地质》2016年第4期942-954,共13页World Geology

基　　金：中国地质调查局项目(12120113098100);国家973项目火山岩油气藏形成机制和分布规律(2009CB219305)联合资助

摘　　要：为了确定饶河玄武岩的构造属性,在野外地质观察的基础上,对玄武岩进行岩石学研究和地球化学分析。玄武岩具有典型的枕状构造、淬冷边、中空骸晶和鬣刺结构等特征,反映其形成于海底喷发环境。化学分析样品具有高TiO2、MgO和低Al2O3、CaO、P2O5、K2O等特征,富集大离子亲石元素（Rb、Sr和Ba）,微量元素蛛网图呈向上隆起形态,稀土元素配分曲线为右倾型（∑LREE/∑HREE为5.8-6.5）,无δEu异常（0.92-0.97）,表明样品具有洋岛玄武岩特征。主量和微量元素构造环境判别图指示了样品形成于洋岛或板内环境。样品与亚速尔型和夏威夷型洋岛玄武岩地球化学特征对比,表现出明显的夏威夷型洋岛玄武岩特征。岩石源区分析揭示出岩浆具有地幔热柱起源,并有先期交代地幔熔体的混入,岩浆源区还受壳幔循环的影响。研究表明,饶河枕状玄武岩为夏威夷型洋岛玄武岩,形成于洋壳消减阶段的洋中脊轴外板内喷发环境,为饶河地区存在成熟的洋盆提供直接证据。结合区域研究成果,认为饶河地区经历了古太平洋板块的扩张、洋中脊轴外板内地幔柱上涌、洋壳俯冲消减以及向佳木斯地块仰冲增生的构造演化过程。Based on field geological investigation,petrological research and geochemical analysis are carried on to confirm the tectonic implication of the Raohe basalt.The studies indicate that the basalt has typical characteristics of pillow structure,quenching rim,intermediate hollow skeletal and spinifex textures,revealing that they are formed in the environment of submarine eruption.The analysis samples show geochemical features of high TiO2,Mg O and low Al2O3,CaO,P2O5 and K2O,and are enriched in large ion lithophile elements（Rb,Sr and Ba）.While the trace element spider diagram shows a upward type,and the REE diagram shows a right deviation（∑LREE/∑HREE is 5.8 - 6.5） without δEu anomaly（0.92 - 0.97）,indicating the characteristics of ocean island basalts.Tectonic discrimination diagrams of major and trace element reveal that they are formed in the oceanic island and intra-plate setting.Compared with the geochemical characteristics of Azores-type and Hawaii-type oceanic island,the samples show the significant characteristics of Hawaii-type ocean island.The studies of source and petrogenesis suggest the samples derivated from mantle source,added melting metasomatic mantle,and influencedby the circulation between mantle and crust.The results implied that the Raohe pillow basalt belongs to Hawaii-type ocean island basalt,and formed in the intra-plate setting of off-axis volcanism during the stage of oceanic crustal consumption,providing direct evidence to the existence of mature ocean basin in the Raohe area.Combining with the regional geological research,the authors suggest that the Raohe area experienced tectonic evolution of the paleoPacific plates expansion,mantle plume upwelling in the intra-plate setting of off-axis,oceanic crustal consumption,obduction-accretion with Jiamusi Massif.

关 键 词：饶河 枕状玄武岩 洋岛 夏威夷型洋岛 黑龙江省 

分 类 号：P588.145[天文地球—岩石学] P595[天文地球—地质学]