CHEMICAL COMPOSITION AND PALEOENVIRONMENTAL RECORD OF THE CO-RICH CRUST FROM MAGELLAN SEAMOUNT IN WESTERN PACIFIC

The Co-rich crust samples collected from the Magellan seamounts in the West Pacific have been analyzed for their compositional characteristics in micron scale by using EPMA. The growth rate and age of the samples are calculated according to the concentration of Cobat. Combined with the data from previous researches, paleoenvironmental records of the sample have been further explored. The results show that the average concentration of Mn, Fe, Co, Ni, Cu, Ca、P and Al in the samples is 29.04%、17.40%、0.73%、0.33%、0.15%、1.72%、0.35% and 0.45% respectively. Compared with the average value of elements in the Co-rich crusts from the Mid-Pacific, Northwest Pacific, Atlantic and Indian ocean, the composition of element chemistry of the samples is characterized by high Mn, Co and low Ni. Dating data shows that the crust is 19.26 Ma in age and there is a hiatus from 11.3 Ma to 8.05 Ma, upon which the growth rate of the sample was calculated; Further studies reveals that the ratios of Al/(Fe+Mn), Co/(Ni+Cu) and Fe/Mn records of the samples may indicate the evolution of the Asian monsoon, the oxidation of seawater and the changes in paleoclimate between icehouse and warming periods.