Abstract: The mineral composition and the concentration of oreforming and rare earth elements of different structure layers in the Cocrust from the YJA sea mount in the central Pacific ocean, were determined using ICPAES, ICPMS, XRD, FTIR and JSM. The results show that this crust is a large of plank new crust,ore mineral is vernadite, gangue minerals are quartz, plagioclase and apatite, minor minerals are montmorillonite, kaolinite, natrolite, hydrobiotite and heulandite and so on. The contents of total Mn, Ni, Cu, Ba, Zn are gradually decreased from lower to upper the structure layers while TFe increased and Co keep almost unchanged. Si, Al, K, Na, Ca, Mg, Ti, P, Li and Rb are relatively enriched in the loose structure layers. In the crust, total REE content are 1 982.27×10-6 and Ce is distinctively positive anomalies.The varied tendency of Ce is similar to Mn while other REE (excepting Y) are more like Fe.

Key words: Pacific ocean, Corich crust, mineral composition, element geochimestry