Geochemical Characteristics Of Basalt And Research On Co-Rich Crust Formation In The Mid-Pacific CH Seamount

This paper will through the analysis of the co-rich crust forms and geochemicalcharacteristics of co-rich crust and basalt on CH sea mountain in mid-pacific ocean todiscuss rich cobalt crust, basement features and relationship between them. It will begreat significant in seamount evolution and co-rich crust material sources. Mainresearch results are as follows:The main elements of CH Seamaunt basalt shows that the basalt is tephrite，belong to alkaline series。Basalts standardized trace element distribution patternssimilar to OIB, enrichment in large ion lithophile elements （LILE） and incompatiblehigh field strength elements （HFSE）,showing the trace element characteristics ofintraplate OIB. REE distribution pattern are right-slop type, enriched in LREE，indicating that there is a higher degree of LREE fractionation and the low degree ofpartial melting of mantle source.Through the study of the main elements, trace elements and rare earth elementsgeochemical，shows that basalt belongs to the OIB， in the process of basaltic magmaformation and evolution, partial melting effect is small, only experienced monoclinicpyroxene crystallization process, and is not subjected to crustal contamination ofmaterials.Compared with other OIB,CH seamount basalt mantle source regioncontains EM type mantle, and has the characteristics of the enriched mantle. Mantleplume is the deep seamounts formation dynamics mechanism, deduce the evolutionprocess of the seamounts: in the process of drift, the Pacific plate experienced hotactivities and reformed by fault activities, finally formed the current distributedclusters of sea mountains.Co-rich crust of main ore-forming metallic elements Mn, Fe, Co, Ni, Cu content are very high, the Co content is0.52⁰.86%, achieve the ore grade, suggests thatrich cobalt crust in this area may have the value of further exploration andexploitation. Fe, Mn have important control function for other metal elements.Comprehensive analysis, the Co concentration process is probable Co3+and vernaditeMn⁴⁺replacement process, the Cu concentration process is mainly amorphous ironhydroxide adsorption process of organic matter containing Cu, Ni in water hydroxylmanganese ore concentration process is not clear. From the rare earth elementdistribution graph, all samples have similar distribution patterns of overall and are alllight rare earth element enrichment, no Eu anomaly, Y negative anomaly; Ce contentis727.8×10^-6842.9×10^-6, characterized by positive anomaly, δCe value of1.58¹.58,shows that co-rich crust was formed in oxidizing environment. Most of the content oftrace elements and rare earth elements content has strong positive relationship withMn, Fe, shows hydroxyl manganese ore of iron hydroxide and vernadite haveimportant influence on the enrichment of rare earth and trace elements.By the cobalt-rich crusts’ main elements ratio compared with the average watermain elements ratio, come to a conclusion that basaltâ†'waterâ†'Co-rich crust materialproviding relationship, illustrates basalt indirect supplies material for crust. Richcobalt crust and basalt of chondrite standardized distribution curve of trace elementand rare earth element curves have similar shape, can be thought of rich cobalt crust’strace elements, rare earth elements could be a big part of from basalt. Fresh basalt,altered basalt and rich cobalt crust of rare earth elements comparison showed that inthe basalt the alteration process and the formation process of rich cobalt crust, reeelements corresponding reduce process and increase process.