东太平洋和中太平洋海盆铁锰结核的物质组成、成矿介质和成矿作用研究

IOCAS-IR > 海洋环流与波动重点实验室

	东太平洋和中太平洋海盆铁锰结核的物质组成、成矿介质和成矿作用研究
	姚德
学位类型	博士
导师	陈丽蓉
	1993
学位授予单位	中国科学院海洋研究所
学位授予地点	中国科学院海洋研究所
学位专业	海洋地质学
摘要	本文在区域背景分析的基础上，详细研究了中太平洋CP区（7°-12°N，176°E-178°W）和东太平洋CC区（7°-14°N，138°-152°W）铁锰结核的铁锰矿物组成、化学成分、成矿介质特征及其形成控制因素，结果表明：铁锰结核内部构造具有几乎由纯的铁锰氧化物组成的平行纹层状构造到含有较多碎屑矿物粘土矿物的斑杂状构造的连续过渡特征；铁锰结核中的锰矿物主要是δ-MnO_2、钡锰锰矿和钠水锰矿，且以前两者为主，在以平行纹层状构造为主的结核中富δ-MnO_2、贫钡镁锰锰，δ-MnO_2/钡镁锰矿比值大于10，而在以斑杂状构造为主的结核中δ-MnO_2/钡镁锰矿的比值在1左右，铁矿物主要是针铁矿、四方纤铁矿等；铁锰结核中的化学元素可以分成五个具有独立成因意义的组合：锰元素组、铁元素组、造岩元素组、生物成因元素组和易溶盐类组分，具平行纹层状构造富含δ-MnO_2的结核中富集铁组元素，具斑杂状构造富含钡锰锰矿的结核富集锰组元素和造岩元素；铁锰结核中稀土元素含量是正常深海沉积物的2-3倍。水成型结核和混合成岩型结核上部稀土元素更富且具Ce的明显正异常，而成岩型结核和混合成因结核的下部稀土元素含量相对低，Ce的正异常也不明显，有时出现负异常；铁锰结核的直接成矿介质是大洋底层水和孔隙水，因此底层水和孔隙的物理化学条件就是决定结核地球化学特征的关键条件，影响大洋底层水、孔隙水物理化学条件变化的地质因素主要有南极底流、沉积速率、生物生产力等等；铁锰结核的生长是一非线性振荡式的地质地球化学作用过程。
其他摘要	On the basis of analysis of regional geological setting, mineralogy, chemistry, ore-forming fluid and their controlling factors of the ferromanganese deposits from the CP area (7°-12°N, 176°E-178°W) in the Central Pacific and the CC (7°-14°N, 138°-152°W) in the eastern Pacific were studied in detail. It is concluded that: 1. There is a continuous transition from parallel laminated structure which consists of comparably pure oxides of Mn and Fe to irregular laminated structure which contains significant detrital minerals and authigenic silica-alumina minerals between the types of innerstructures of ferromanganese nodules. 2. Manganese minerals in ferromanganese nodules are mainly -MnO_2 (vernadite), toderokite and birnessite, and -MnO_2 and toderokite are dominant. Iron minerals in the nodules are mainly goethite and akaganeite, -MnO_2 is the dominant manganese mineral in the nodules in which the main innerstructure type is parallel laminated (hydrogenic), and in this case-MnO_2/toderokite ratios are generally great than 10. Toderokite is richest in the nodules in which the main innerstructure type is irregular laminated (diagenetic), and in this case @-MnO_2/toderokite ratios are about 1. The @-MnO_2/toderokite ratios in mixed origin (hydrogenic and diagenetic) are in the middle. 3. There is obviously a element assemblage law in ferromanganese nodules, and at least the elements in the nodules can be divided into five groups: 1) manganese-phile elements, including Mn, Cu, Ni, Zn, Mg, Mo, Sb, Ba etc., 2)iron-phile elements, including Fe, Co, Pb, Ti, REE, Sr, Sc, As(u, Th, Ca, P, Hf, V) etc., 3) general rock-forming elements, including Si, Al, K, Na, Ca, Rb, (Ba, Sr) etc., 4) biogenetic elements, including P, (Si, Ca, U, Th, REE) etc. and 5) elements forming lysosensitive salts, including Cl, (Na, Ba) etc. 4. In comparation with common deep sea sediments, ferromanganese nodules are obviously rich in REE. REE in nodules is 2-3 times higher than those in common deep sea sediments. The factors controlling REE distribution in ferromanganese nodules are innerstructure, mineralogy and geochemistry of the nodules and physi-chemical conditions of the environment in which the nodules are formed. The hydrogenic nodules have higher REE than diagenetic nodules do, and the hydrogenic nodules have violently positive Ce anomalies, but diagenetic nodules have weak positive or negative anomalies. The nodules from seamounts and deep sea plateaus have higher REE and more obvious positive Ce anomalies than the nodules from deep sea plains and depression do. The REE distributions in ferromanganese nodules from deep sea hill in the middle of that of nodules from seamounts and deep sea plateaus and deep sea plains and depressions. The geological and geochemical characteristics of ploymetallic nodules are closely related to morphology and sediment type in the place where the nodules formed. The nodules from seamounts and the tops of deep sea hills are mainly hydrogenic, but the nodules from deep sea plains and depressions are obviously influenced by diagenesis. 5. The direct ore-forming fluid of ferromanganese nodules is oceanic bottom water and pore water in sediments. Therefore, the physi-chemical condition of ore-forming fluid is key factor controlling geochemistry of ferromanganese nodules and being controlled by AABW, sedimentation rate, biological productivity, and so on. 6. The growth of ferromanganese nodules is a geological process of nonlinear vibration.
页数	80
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/1075
专题	海洋环流与波动重点实验室
推荐引用方式 GB/T 7714	姚德. 东太平洋和中太平洋海盆铁锰结核的物质组成、成矿介质和成矿作用研究[D]. 中国科学院海洋研究所. 中国科学院海洋研究所,1993.

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