Research On Contrast And Controls Of Polymetallic Nodules From Eastern Pacific CC Zone And East Mariana Basin

The polymetallic nodules collected from the east Pacific CC zone and the East Mariana Basin are used in this study.We made comparison between the surface and different part of one nodule and nodules from different regions.Based on geochemistry and mineralogy of nodule surface,we study the differences between different nodules and different layers of one nodule in modern marine environment.And we focus on the main controls of the formation of nodules and elements distribution.The study used various observations and analytical techniques including X-ray diffraction(XRD),Inductively Coupled Plasma Mass Spectrometry(ICP-MS),Inductively Coupled Plasma Optical Emission(ICP-OES)and Electron Probe Micro-analyser(EPMA).The studies are including mineralogy and element geochemical characteristics and controls of the differences between different samples.Results are as follows:1.The elements and mineral analysis of polymetallic nodules surface samples are carried out.Fe,Co,Al,? REY and ?Ce are higher in upper surface than lower surface,while Mn,Cu,Ni,Mn/Fe,and ? REY are higher in lower surface.The sample of CCZ has more Mn,Cu,Ni,Mn/Fe,?REY,and less Fe,Co,Al,P,?Ce,most rare elements than EMB.As for mineralogy,main mineral phase of nodules are vernadite and 1nm manganite.Content of vernadite is more than 1nm manganite in upper surface,and by the contrast less in the lower surface.Regionally,the nodule in EMB has more vernadite and less 1nm manganite than CCZ.2.Fe and Mn in the internal part of the polymetallic nodules are differentially distributed with the upper and lower parts,but the characteristics are not obvious.Cu and Ni in the boundary dense layer is relatively high in concentration and the distribution of Co concentration is homogeneous.Overall,the distribution of elementsin nodules shows a certain periodic cycle,but not the same as the outer layer with the differences between upper and lower surface.3.According to the ratio of Ce anomalies with YSN/HoSN and Nd of rare earth element,the polymetallic nodules in this study are all hydrogenetic.And its formation is the result of many factors,instead of a certain factor.All the available evidences suggest that the formation of nodules is mainly effected by microbial action and colloid adsorption coagulation precipitation.The concentrations of elements are significantly different in microstructure of Nodules.In addition to the affection of structural characteristics,it is mainly controlled by the mineral phases.4.Considering all the controls of the characteristic difference mentioned above.Under the influence of Antarctic Bottom Water and the seabed sediment,the dissolved oxygen content,ion concentration and pH value control the distribution of mineral and elements in the nodule surface directly.What's more,the distribution of minerals in nodules further controls the distribution of elements.Therefore,the differences of elements in different layers and different nodules are controlled by the Antarctic bottom flow,surface primary productivity,and environmental parameters directly and indirectly.