Petrochemistry,geochronology,trace and REE geochemistry have been studied of a few basalts from the South China Sea.The results show that the South China Sen basalts may be divided into two types;alkali basalts and tholeiites.The former is similar to common alkali basalts in petrochemistry,REE distribution pattern and trace element geochemistry,but the latter is similar to Hawaiian tholeiites,belonging to the transition type between alkali basalt and MORB(mid-oceanic rise basalt).
REE geochemistry has been studied with respect to sea-floor sediments in the continental shelf of East China Sea. The average content of RE2O3 is derived as 175 ppm based on 68 samples of the continental Y and La-Lu in the abovementioned shelf sediments, The absolute concentrations of sediments are shown in Table 3. The REE distribution patterns of the sediments demonstrate a distinct depletion in Eu and a negative slope. It is considered that the fragments of Mesozoic intermediate-acid igneous rocks widely distributed in southeastern China are the main souree of REE in sea-floor sediments of the continental shelf.
