南海东部次海盆海山链多金属结核(壳)地球化学特征及成因

为了进一步解释南海不同区域内多金属结核（壳）的地球化学特征与成因，对东部次海盆黄岩?珍贝海山链上新获取的多金属结核（壳）样品进行了X光衍射、X荧光光谱测试、SEM-EDS分析和X Series2 ICP-MS测试，详细分析了样品的矿物组成、地球化学成分特征. 结果表明，矿物组成为水羟锰矿、石英、斜长石等；主要造岩元素中Si、Al含量较高，与陆缘碎屑物影响较大有关；富含Mn、Fe、Co、Ti、Ni、Pb、Sr等多种金属元素，相比南海其他区域，具有中等的Fe、Mn含量特征，地化元素特征与南海西北陆坡发现的铁锰结核（壳）相似；稀土元素具有总量高（平均2 070.01×10-6）的特点，高于南海北部其他样品，与西太平洋结壳稀土含量接近（接近工业品位），指示了重要的稀土资源前景. 结核Be同位素结果指示该区铁锰结核生长时代为1.17~8.51 Ma，形成于晚中新世大量火山喷发之后，因此水成作用是南海东部次海盆海山链结核（壳）的主要控制作用，而陆源物质的输入、火山作用和高压富氢离子海水的浸取作用都为结核（壳）的形成提供了有利的沉积环境. 

Geochemical Characteristics and Genesis of Polymetallic Nodules (Crusts) in Seamount Chain of Eastern Subbasin,South China Sea

In order to further explain the geochemical characteristics and genesis of polymetallic nodules (crusts) in different regions of the South China Sea, X-ray diffraction, X-ray fluorescence spectroscopy, SEM-EDS analysis and X-Series analysis were carried out on the newly obtained polymetallic nodules (crusts) from the Huangyan-Zhenbei seamount chain in the eastern Subbasin. The mineral composition and geochemical characteristics of polymetallic nodules (crusts) were analyzed by ICP-MS. The results show that the mineral compositions of polymetallic nodules (crusts) are hydroxidite, quartz and plagioclase, and the main rock forming elements are Si and Al. It is rich in Mn, Fe, Co, Ti, Ni, Pb, Sr, Cu and other metal elements. Compared with other areas in the South China Sea, it has the characteristics of medium Fe and Mn contents, and the geochemical element characteristics are similar to those of ferromanganese nodules (crusts) found in the northwest slope of the South China Sea. The REE content of nodules (crusts) in the study area is high (average 2 070.01×10-6), which is higher than other samples in the northern South China Sea, and close to the industrial grade of crusts in the West Pacific, indicating its important rare earth resource prospect. The results of Be isotope indicate that the age of Fe Mn nodules in this area is 1.17?8.51 Ma, which was formed after a large number of volcanic eruptions in the Late Miocene. Therefore, the hydrogenesis is the main control of the seamount chain nodules (crusts) in the eastern Subbasin of the South China Sea, and the input of terrigenous materials, volcanism and leaching of high-pressure hydrogen rich seawater all provide favorable conditions for the formation of nodules (crusts).