The Study Of Petrological Geochemistry Of Basalts From CL Seamount, Middle Pacific

As an important part of the Middle Pacific seamounts area, Co-rich crusts distribute widely in CL Seamount. The study of petrological geochemistry of Basalts from CL Seamount can help us find out the important effect of the mantle plume in seamounts formation, consequently knowing geochemical characteristic of the mantle plume more. Researching the basalts of seamounts and the development of the seamounts formation is very important to the Co-crusts study and distribution rules.This paper reports the result of a petrological geochemistry study of twenty-one samples from CL Seamount. The samples are basalt or olivine basalt, alkalic basalt, belonging to alkalic series; the minerals assemblages are plagioclase(An=52~79), chrysolite, augite and amphibol. Compared to oceanic subalkaline basalt they have higher Fe2O3, Na2O, lower SiO2, FeO, MgO. CL Seamount basalts are enriched in LILE, LREE, and HFSE; REE patterns are right-leaned and have negative Ce abnormity (La=60.65~329.03, (La/Yb)N=7.08~15.3, 5 Ce=0.48~0.91). The content of Nb and Ta of CL Seamount is more decuple than those of MORB, it indicates obvious character of OIB; HFSE/HFSE, LILE/HFSE, LILE/LILE values are similar to those of EM. This suggests the CL Seamount magma is not affected by subduction composition. Compared with petrological geochemistry of basalts from other seamounts and ocean islands, it concludes that the trace element character is similar to those of the Selvagen Seamount basalts whose formation is closely associated with hotpot. This suggests that the resource of CL Seamount basalts is aborigine from EM component and its formation is closely associated with hotpot and mantle plume.