GEOLOGICAL CHARACTERISTICS OF POLYMETALLIC NODULES IN THE CENTRAL INDIAN OCEAN AND COMPARISON WITH THOSE FROM CC ZONE IN THE EASTERN PACIFIC
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摘要: 利用"大洋一号"2007年在中印度洋海盆采集的多金属结核和沉积物样品,采用X射线衍射、穆斯堡尔谱、X荧光分析、ICPMS等方法,对样品进行了矿物学和化学成分分析,并与东太平洋海盆我国开辟区多金属结核进行了对比。印度洋结核区海底沉积为含黏土硅质软泥,结核呈菜花状、碎屑状、杨梅状和连生体4种类型产出,大小为0~6cm,平均丰度4.213kg/m2,矿物有钙锰矿、水羟锰矿、水钠锰矿、针铁矿,其次为钙十字沸石、石英等,平均品位(Cu+Co+Ni)2.39%,菜花状结核富Mn、Ni、Cu (Mn/Fe=5.09~6.33),连生体状结核富Fe、Co (Mn/Fe=1.03~1.36),结核的页岩标准化稀土元素配分模式基本一致,表现为轻稀土富集、正Ce异常,但连生体状结核稀土总量和Ce的异常远远高于菜花状结核。中印度洋海盆结核与东太平洋海盆结核具有类似的矿物组成和稀土配分模式,可能具有类似的成因模式,但前者的平均丰度和品位均低于后者。Abstract: The mineralogy and chemical components of polymetallic nodules and sediment samples collected by R/V DAYANG YIHAO in the central Indian Ocean in 2007 were studied by means of XRD,Mossbaure, XRF and ICPMS.The nodules occur in siliceous ooze in shapes of cauliflower,fragment,waxberry and parallel nodules.Medium-sized and small nodules are dominant,with an average abundance of 4.213kg/m2.The nodules consist of todorokite,vernadite,birnessite and goethite with small amount of phillipsite, quartz etc.The average grade or the total content of Cu,Co and Ni is 2.385%.The cauliflower-shaped nodules are rich in Mn,Ni,Cu,with a high Mn/Fe ratio(5.09~6.33),and the parallel nodules are rich in Fe,Co,with a low Mn/Fe ratio(1.03~1.36).The REE patterns of the nodules are basically similar, characterized by LREE enrichment and a positive Ce anomaly.However,the total REE and Ce anomaly of the parallel nodules is much higher than that of the cauliflower-shaped nodules.The nodules from central Indian Ocean basin have similar mineral composition and REE patterns with those of eastern Pacific basin, suggesting that they possibly have similar origin,but the average abundance and grade of the nodules from central Indian Ocean basin is lower than those from the eastern Pacific basin.
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