GEOCHEMICAL CHARACTERISTICS OF LATE CENOZOIC BASALTS IN LEIQIONG AREA AND THEIR DYNAMIC SIGNIFICANCE
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 en-riched components are derived from subducted oceanic crust and sediments.Further initial melt re-covery 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 tri valent iron in the samples should be strengthened in the follow-up study,so as to provide a basis for the initial melt re-covery and the inversion of the properties of the mantle source region.At the same time,it is neces-sary to strengthen the comprehensive comparison between Leiqiong and other contemporaneous ba-salts around the South China Sea Basin to better explore the nature and evolution of the regional mantle.
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