| Summary: | 碩士 === 國立臺灣師範大學 === 地球科學系 === 98 === Leiqiong area is located at the south of China in East Asia, South China Sea in the east, Red River - Ailaoshan shear zone in the west. During Cenozoic, it is active region of volcanic activity. The major elements, trace elements and REE distributions, indicate the same source for Leiqiong magma, with OIB and mantle plume characteristics. In the primitive mantle normalized compatible elements patterns there are positive Ti and negative Cr and Ni anomalies. The negative Cr and Ni anomalies may be related to the fractional crystallization of olivine and clinopyroxene while the positive Ti anomaly may be due to the involvment of rutile in the partial melting process.La/Ce, Ce/Nd, Th/La, Zr/Hf pairs have positive correlation and can be regressioned through the zero point indictating these magmas belong to the same source.Leiqiong magmatic evolution, have experienced partial melting of the upper mantle and crystallization differentiation. The degree of crystallization differentiation for Hainan Island basaltic magma is higher than the Leiqiong magma.
Previous isotope studies suggest that this area may have DMM and EMII source composition. Hainan plume model was proposed to explain EMII source composition of Cenozoic basalts from the South China Sea, and it provided reasonable explanation of EMII source composition of Cenozoic basalts from the study area.
|
|---|
