MORB trace element geochemistry in the eastern of southwest indian ridge and its indication for the composition of mantle source

The eastern of the southwest Indian ridge (E-SWIR) is located between 61° and 70° E, with relatively low melt supply. Most of the mid-ocean ridge basalts (MORB) produced in this area is a typical E-MORB with the characteristics of enrichment of incompatible elements and large ion lithophile elements. Based on the trace element geochemical data of basalt samples, the analysis of La/Sm, Zr/Nb and Lu/Tb shows that the E-SWIR mantle has obvious heterogeneity, which may be related to the axial variation of pyroxenite content in the mantle. Using the contents of rare earth elements Ce, Sm, Lu and Yb in combination with the simulation results of partial melting calculation, the role and influence of garnet in the mantle source area are further clarified, and it is believed that it may exist in the mantle as auriferous garnet pyroxene. The identification of the nature and occurrence form of eclogites in the E-SWIR mantle source region is the key to discuss the origin of E-MORB, mantle heterogeneity and the tectonic evolution of mid ocean ridge.