Geochemical Characteristics and Their Causative Mechanism of Polymetallic Nodules from the Northwest Continental Margin of the South China Sea
ZHANG Zhen-guo
FANG Nian-qiao
DU Yuan-sheng
GAO Lian-feng
YANG Sheng-xiong
LIU Jian
SONG Cheng-bing
Abstract：This study employs various observation and analytical techniques including electron microprobe analysis, X-ray difraction (XRD) and ICP-MS(AES) on polymetallic nodules collected from the northwest continental margin of the South China Sea. The analyses indicate that the cores of the samples are made up of quartz, illite, albite and chlorite, whereas the shells are made up of δMnO_2. The samples are rich in Fe, Si, and 2REE, and they are poor in Mn, Cu, Co and Ni. These samples show lower ratios of Mn/Fe. The characteristics of the REE (rare earth elements) show higher contents with more than 1 472. 30×10~6 in average. Heavy REE (HREE) depletes relative to the light REE (LREE) very obviously that the latter is 19. 54 times than that of the former, and shows distinct enrichment of 8Ce. The elements of Fe, Mn, Cu and Co change obviously in different ways from the inner crust to the outer. These characteristics show that the growth of the nodules has been affected by the environmental fluctuations and the change of terrigenous sediments. In this condition, Fe, REE and Si are enrichment, but Mn and Ca are dilutedness. Elements correlation of Mn-Fe-(Cu+Ni) ×10 suggests that the origin of the sample may be hydrogenic. This study comes to the conclusion that these nodules are dominative due to the special environment of the marginal sea which includes the geographical condition and the oceanic environmental factors.
Keywords：polymetallic nodulesgeochemical characteristicscausative mechanismthe South China Seathe northwest continental margia
Publication Date：2009-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：8( 955-962 )