Characteristics And Genesis Studying Of Co-Rich Crust From West Pacific

The Co-rich crusts contain many rare and precious metals, such as Co, REE andtrace element except for the main elements Mn, Fe, Cu and Ni etc. Because of theusually shallow depth of marine in the deposit area of the crust, which will lead tolower exploration costs and less pollution to marine environment, many countrieshave been investing large capitals in exploring and researching of submarine Co-richcrusts since 1980s.In this study, detailed observation under microscope and systematical studies ofgeochemical of Co-rich crust by some modern analytical methods, which includeEPMA analysis, REE analysis, ICP-MS analysis, XRF analysis, were carried out, andpreliminary discussion that how the Co-rich crust deposited.The analytical results show that:1. The petrologic studying indicates that pyrochroite, quartz, anorthite andfluorapatite are widely distributed in the Co-rich crust. The present of the large ofpyrochroite infers that the forming process of the Co-rich crust once underwent thereductive environments.2. Electric microprobe analysis provides the evident for hydrogenic originbecause of the quite positive correlation between the element Co and Mn in thesample MID and CLD. Correlation coefficients are 0.66 and 0.79 respectively. Thepositive correlation between Co and Mn is the typical characteristic of hydrogenicorigin.3. Trace element analysis shows that there are many trace elements havepositive correlation with the element Co. The strongest positive correlation elementis U with 0.867 of coefficient. Trace element can be divided into three groups withthe result of cluster analysis. (1) Sc, Rb group which include the element Sc, Rb,Cs, Th, Zr, Hf, Ta and Cr. (2) Co, U group which Co, U, Ni, Zn, Ga, Sn, Cu, Ba andZr etc. (3) Y group, only one single element Y. After matching the sample's curvedistribution with the data of other area which are the continental crust, mantle andmarine crust.4. There are great total rare earth element content (∑REE = 1215.86 × 10 – 6 ~2664.23×10-6), positive Ce anomaly (543.68×10-6~1026.40×10-6). Suggesting that theCo-rich crust was once underwent an oxidizing atmosphere. The distribution curveanalysis indicates that the metallogenic elements deposited from upper continentalcrust.