雷琼地区晚新生代玄武岩地球化学特征及其动力学意义  

GEOCHEMICAL CHARACTERISTICS OF LATE CENOZOIC BASALTS IN LEIQIONG AREA AND THEIR DYNAMIC SIGNIFICANCE

作　　者：胡俊 李霓[1,2] HU Jun;LI Ni(Jilin Changbaishan Volcano National Observation and Research Station,Institute of Geology,China Earthquake Administration,Beijing 100029,China;Key Laboratory of Seismic and Volcanic Hazards,China Earthquake Administration,Beijing 100029,China)

机构地区：[1]吉林长白山火山国家野外科学观测研究站,中国地震局地质研究所,北京100029 [2]中国地震局地震与火山灾害重点实验室,北京100029

出　　处：《内陆地震》2024年第1期1-12,共12页Inland Earthquake

基　　金：国家自然科学基金项目(42002066,42272351);中国地震局地质研究所基本科研业务专项(ICEA2306).

摘　　要：晚新生代以来,雷琼地区喷发了大量的玄武岩,众多学者对这些玄武岩进行了研究。然而,关于玄武岩的成因及其反映的动力学意义仍存在争议。为了对雷琼玄武岩进行分类、获得玄武岩的初始熔体组成及地幔潜能温度,整理了雷琼玄武岩的元素及Sr-Nd-Pb同位素地球化学数据,并将其划分为碱性玄武岩、橄榄拉斑玄武岩、石英拉斑玄武岩和玄武安山岩4类。它们具有类似OIB的地球化学特征,同位素组成落在了亏损软流圈地幔和二型富集地幔端元的混合区域,富集组分来源于俯冲的洋壳和沉积物。进一步的初始熔体恢复模拟和地幔潜能温度计算结果显示,雷琼地区的地幔潜能温度高于正常地幔,暗示了海南地幔柱的存在。最后提出建议,后续研究需加强对样品二价铁与三价铁的测定,为初始熔体恢复及地幔源区性质的反演提供依据。同时,需加强雷琼与南海盆地周缘其他同期玄武岩的综合对比,以更好的探讨区域地幔性质及演化。Since the Late Cenozoic,a large number of basalts have erupted in the Leiqiong area,and many scholars have done a lot of research on these basalts.However,the genesis of basalts and their dynamic implications remain controversial.In order to classify the Leiqiong basalts and obtain the initial melt composition and mantle potential temperature of the basalts,this paper collates the elements and Sr-Nd-Pb isotope geochemical data of the Leiqiong basalts in the literature,and divides them into four categories:alkaline basalt,olivine tholeiite,quartz tholeiite and basaltic andesite.They have geochemical characteristics similar to those of OIB,and their isotopic compositions fall in the mixed area of depleted asthenosphere mantle and type-2 enriched mantle endmembers.The enriched components are derived from subducted oceanic crust and sediments.Further initial melt recovery simulation and mantle potential temperature calculation results show that the mantle potential temperature in Leiqiong area is higher than that of normal mantle,suggesting the existence of Hainan mantle plume.Finally,it is suggested that the determination of divalent iron and trivalent iron in the samples should be strengthened in the follow-up study,so as to provide a basis for the initial melt recovery and the inversion of the properties of the mantle source region.At the same time,it is necessary to strengthen the comprehensive comparison between Leiqiong and other contemporaneous basalts around the South China Sea Basin to better explore the nature and evolution of the regional mantle.

关 键 词：雷琼地区 玄武岩 地球化学 地幔柱 

分 类 号：P315.7[天文地球—地震学]