南海北部铁锰结核成因及元素的赋存状态*
作者简介:仲义(1989—), 男, 江苏省连云港市人, 博士研究生, 主要从事海洋沉积矿物学研究。E-mail: zhongyi@scsio.ac.cn
收稿日期: 2016-06-23
要求修回日期: 2016-09-01
网络出版日期: 2017-04-06
基金资助
国家自然科学基金项目(41376057、41676056、41306047)
Genetic types and elemental occurrence phases of ferromanganese nodules in the northern South China Sea
Received date: 2016-06-23
Request revised date: 2016-09-01
Online published: 2017-04-06
Supported by
National Natural Science Foundation (41376057, 41676056, 41306047)
Copyright
为了解南海北部不同海域铁锰结核中常微量、稀土元素的赋存特点及其富集机制, 采用化学淋滤法提取南海北部上陆坡、下陆坡、深海盆3个区域铁锰结核的碳酸盐相、铁锰氧化相、残渣相组分, 测定了常微量元素、稀土元素含量, 揭示了不同相的元素赋存状态及其意义。Fe-Mn-(Cu+Co+Ni)判别图表明, 上陆坡铁锰结核属于与冷泉流体相关的水成成因类型; 下陆坡区和深海盆的铁锰结核形成环境相似, 属于典型的水成成因类型。结核中K、Ca、Na、Mg、Sr主要富集在碳酸盐相, Fe、Mn、Ni、Cu、Zn、Pb主要赋存在铁锰氧化物相, Al、Ti和Mo主要出现在残渣相。常微量元素赋存状态变化受多种因素影响, 钙质生物生产力的强弱和钙质生物碎屑的稀释作用是影响铁锰结核中碳酸盐相态元素变化的重要原因。铁锰结核的稀土元素主要富集在铁锰氧化物相, 其次在碳酸盐相, 而在残渣相的相对含量极少。不同海区铁锰结核稀土元素进入碳酸盐相的成因和机制基本相似, 下陆坡和深海盆铁锰结核残渣相稀土元素配分模式相似, 而与上陆坡铁锰结核的明显不同, 残渣物质的来源、结核生长环境的氧化还原状态差异是主要影响因素。研究成果可为深入研究铁锰结核的元素迁移与转化、成矿作用与成矿物质来源及其相关的沉积环境、资源潜力评价等提供重要的基础资料。
仲义 , 陈忠 , 莫爱彬 , 罗云 , 黎刚 , 郑旭峰 . 南海北部铁锰结核成因及元素的赋存状态*[J]. 热带海洋学报, 2017 , 36(2) : 48 -59 . DOI: 10.11978/2016060
To understand the elemental occurrence phases and the origin of ferromanganese nodules in the northern South China Sea, selective leaching techniques have been utilized to study the geochemical phases (viz. carbonate, Fe-Mn oxide and residual) of ferromanganese nodules on the upper continental slope and the lower continental slope, as well as in the deep-sea basin. According to the Fe-Mn-(Cu+Co+Ni) diagram, Fe-Mn nodules around the Dongsha Islands are associated with hydrocarbon seeps. Nodules on the lower continental slope and in the deep-sea basin have a similar formation mechanism, and are both hydrogenous in origin. K, Ca, Na, Mg, and Sr are mainly enriched in the carbonate phase; Fe, Mn, Ni, Cu, Zn, and Pb are mainly concentrated in the Fe-Mn oxide phase; Al, Ti and Mo are mainly concentrated in the residual phase. The variation of elemental occurrence phases is influenced by multiple factors. The strength of biological productivity and the dilution of calcareous bioclast material can result in change of carbonate phase of Fe-Mn nodules. On the lower continental slope and in the deep-sea basin, REEs and yttrium are mainly associated with the Fe-Mn oxide phase. However, the carbonate and residual phases of hydrogenous oxides have extremely low REE content. The REE origins in carbonate phases of Fe-Mn nodules from different areas are basically similar. The Fe-Mn nodules in the slope area and deep-sea basin have identical residual phase distribution of REEs and yttrium except for the upper slope area. It is probably influenced by residual sources and redox environment of the Fe-Mn nodules. This study discusses the elemental chemical phases in Fe-Mn nodules in the northern South China Sea and provides important basic data for the resources evaluation in this area in the future.
Tab. 1 Location and morphology of Fe-Mn nodules表1 铁锰结核站位及其形貌 |
海区 | 站位 | 东经 | 北纬 | 水深/m | 样品号 | 形貌特征 |
---|---|---|---|---|---|---|
上陆坡 | 05E204 | 117°57′5.22″ | 20°59′7.8″ | 1370 | 05E204-1 | 球状, 直径约2cm |
10E204 | 117°59′12.504″ | 21°0′21.618″ | 1785 | 10E204-1 | 长条状 | |
10E204B | 117°57′18.852″ | 21°0′9.774″ | 1331 | 10E204B-1 | 棒状 | |
下陆坡 | 05E107 | 117°09′31.68″ | 19°46′25.8″ | 2255 | 05E107-1 | 球状, 直径3cm |
05E107-3 | 菜花状, 核心杂质多 | |||||
05E107-5 | 不规则块状 | |||||
05E107-6 | 椭球状, 半径5~8cm | |||||
05E107-7 | 扁球状, 直径约7cm | |||||
深海盆 | J-158 | 117°45′12.36″ | 17°33′41.76″ | 3570 | J-158-1 | 球状, 表层光滑 |
Fig. 1 Sampling locations of Fe-Mn nodules in the northern South China Sea图1 南海北部铁锰结核位置图 |
Fig. 2 Morphological features and inner structures of the polymetallic nodules图2 铁锰结核形貌及内部结构 |
Fig. 3 Experimental flow chart used in the elemental occurrence phase analysis图3 元素赋存状态分析实验流程 |
Fig. 4 Ternary diagrams for classification of the Fe-Mn nodules图4 南海北部铁锰结核成因类型判别图 |
Fig. 5 Major and trace element abundances in three leachates (easily exchangeable, Fe-Mn oxide and residual) of Fe-Mn nodule samples from (a) the upper slope area, (b) the lower slope area and (c) central basin area图5 南海北部上陆坡区(a)、下陆坡区(b)和海盆区(c)铁锰结核不同相态主微量元素含量分布图 |
Fig. 6 Comparative REE-yttrium abundances in three leachates (easily exchangeable, Fe-Mn oxide and residual) of ferromanganese nodules from (a) the upper slope area, (b) lower slope area and (c) central basin area.图6 南海北部上陆坡区(a)、下陆坡区(b)和海盆区(c)铁锰结核不同相态常微量元素含量分布图 |
Tab. 2 REE geochemical characteristics in different phases of Fe-Mn nodules from the northern South China Sea表2 铁锰结核不同赋存状态下稀土元素地球化学参数 |
参数 | 碳酸盐相 | 铁锰氧化物相 | 残渣相 | |||||||
---|---|---|---|---|---|---|---|---|---|---|
上陆坡 | 下陆坡 | 海盆 | 上陆坡 | 下陆坡 | 海盆 | 上陆坡 | 下陆坡 | 海盆 | ||
ΣREE | 23.69~36.25 | 53.83~84.48 | 55.67 | 40.68~106.90 | 783.42~884.61 | 605.55 | 2.10~2.39 | 62.82~86.32 | 36.07 | |
ΣLREE | 19.55~31.09 | 44.38~70.58 | 47.33 | 37.16~97.33 | 730.18~832.62 | 560.31 | 1.77~2.10 | 60.22~82.73 | 33.85 | |
ΣHREE | 4.14~5.41 | 9.45~13.90 | 8.33 | 3.52~9.57 | 53.24~61.10 | 45.23 | 0.29~0.38 | 2.60~3.60 | 2.22 | |
ΣLREE/ΣHREE | 4.72~7.14 | 4.70~5.22 | 5.68 | 8.33~10.54 | 12.55~13.72 | 12.60 | 4.71~7.29 | 23.01~23.36 | 14.98 | |
Ce/Ce* | 0.62~1.10 | 0.35~0.52 | 0.68 | 1.63~2.40 | 2.40~3.10 | 3.35 | 0.83~1.59 | 6.59~8.88 | 4.66 | |
Eu/Eu* | 1.09~1.15 | 1.25~1.27 | 1.26 | 1.10~1.15 | 1.14~1.18 | 1.21 | 0.05~0.06 | 0.74~1.28 | 0.57 | |
YN/HoN | 0.98~1.09 | 0.73~0.83 | 0.85 | 0.79~0.90 | 0.55~0.60 | 0.65 | 0.76~0.91 | 0.50~0.55 | 0.63 |
注: 1) ΣREE、ΣLREE、ΣHREE分别代表稀土总量、轻稀土和重稀土总量, REE包含元素La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu; 2) Ce/Ce*=2Ce/(LaN + PrN), Eu/Eu*=2EuN/(SmN + GdN); N为页岩标准化(PAAS)。 |
Fig. 7 Shale (PAAS) normalized REE-yttrium distribution patterns in different phases of Fe-Mn nodules in the northern South China Sea图7 南海北部不同海区铁锰结核中稀土元素的页岩标准化配分模式图 |
Fig. 8 Shale (PAAS) normalized REE-yttrium distribution patterns of other types of samples图8 不同类型样品稀土元素中页岩标准化稀土元素配分模式 |
The authors have declared that no competing interests exist.
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