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| 麦哲伦海山群富钴结壳元素地球化学特征及赋存状态 |
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高晶晶1,2,3, 刘季花1,2,3, 张辉1,2,3, 闫仕娟1,2,3, 汪虹敏1,2,3
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1.自然资源部第一海洋研究所 自然资源部海洋地质与成矿作用重点实验室 山东青岛 266061;2.青岛海洋科学与技术试点国家实验室 海洋地质过程与环境功能实验室 山东青岛 266237;3.山东省深海矿产资源开发重点实验室(筹) 山东青岛 266061
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| 摘要: |
| 为探究大洋富钴结壳的元素地球化学特征和赋存状态，以西太平洋麦哲伦海山群5个富钴结壳样品为研究对象，通过X射线衍射法、等离子体发射光谱法、等离子体质谱法及相态分析手段，分析了富钴结壳的矿物组成、主量元素和稀土元素含量。结果表明，富钴结壳样品主要结晶矿物为水羟锰矿，次要矿物包括石英、斜长石和钾长石，同时含有大量非晶态铁氧/氢氧化物。富钴结壳样品中Mn和Fe含量最高，Mn为16.87%~26.55%，Fe为14.34%~18.08%。富钴结壳明显富集稀土元素，其稀土总量为1 287~2 000μg/g，Ce含量为632~946μg/g，约占稀土总量的50%；轻稀土含量为1 037~1 604μg/g，重稀土含量为249~395μg/g，轻稀土元素明显高于重稀土元素。稀土元素配分模式呈现Ce正异常而Eu无异常，具有Ce富集特征。麦哲伦海山群富钴结壳是水成沉积成因，基本没有受到海底热液活动和成岩作用的影响。元素赋存状态与其矿物相密切相关，Na、K、Ca、Mg和Sr主要赋存于碳酸盐相，Mn、Ba、Co和Ni主要赋存于锰氧化物相，Fe、Al、P、Ti、Cu、Pb、V、Zn、Zr和REE主要赋存于铁氧化物相，部分Al和K赋存于残渣态。该研究对于西太平洋麦哲伦海山群富钴结壳的成矿理论研究提供了科学依据。 |
| 关键词: 麦哲伦海山群 富钴结壳 地球化学 赋存状态 |
| DOI：10.11693/hyhz20220600149 |
| 分类号:P736 |
| 基金项目:崂山实验室科技创新项目，LSKJ202203602号；国家自然科学基金项目，40976038号；国际海域资源调查开发“十三五”资源环境课题，DY135-C1-1-04号。 |
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| GEOCHEMISTRY AND OCCURRENCE PHASE OF THE ELEMENTS IN COBALT-RICH CRUSTS FROM THE MAGELLAN SEAMOUNTS |
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GAO Jing-Jing1,2,3, LIU Ji-Hua1,2,3, ZHANG Hui1,2,3, YAN Shi-Juan1,2,3, WANG Hong-Min1,2,3
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1.Key Laboratory of Marine Geology and Metallogeny, MNR, First Institute of Oceanography, Qingdao 266061, China;2.Laboratory for Marine Geology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China;3.Key Laboratory of Deep Sea Mineral Resources Development, Shandong (Preparatory), Qingdao 266061, China
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| Abstract: |
| To explore the geochemistry and occurrence phase of the elements in cobalt-rich crusts from the ocean, three cobalt-rich crusts samples from Magellan Seamounts in western Pacific were chosen for this research, for which X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS) and phase analysis methods were used to analyze the mineral composition, major elements contents, and rare earth elements (REE) contents in the cobalt-rich crusts. Results show that the main crystalline minerals are vernadites, and the minor minerals include quartz, plagioclase, and potassium feldspar. Also, many amorphous ferric minerals are contained in the cobalt-rich crusts. Meanwhile, Mn and Fe contents are the highest in abundance. Mn contents are 16.87%~26.55%, and Fe contents are 14.34%~18.08%. REEs are enriched in cobalt-rich crusts in a range of 1 287~2 000 µg/g, and Ce contents of 632~946 µg/g; Ce is nearly half of REE in content. Moreover, light rare earth elements (LREE) contents are 1 037~1 604 µg/g, and heavy rare earth elements (HREE) contents are 249~395 µg/g; the LREE contents are more than HREE in cobalt-rich crusts. REE diagrams show the positive Ce anomalies and no Eu anomalies, thus Ce is enriched in cobalt-rich crusts. In addition, cobalt-rich crusts from then Magellan Seamounts are hydrogenetic deposits, and they are basically not affected by hydrothermal action and diagenesis. Meanwhile, the occurrence phases of the elements are closely related to minerals. Na, K, Ca, Mg, and Sr are mainly enriched in carbonate phase, Mn, Ba, Co and Ni are mainly enriched in iron oxide phase, Fe, Al, P, Ti, Cu, Pb, V, Zn, Zr, and REE are mainly enriched in the iron oxide phase, and Al and K are partly enriched in the residual phase. This study enriched scientific data of metallogenesis in cobalt-rich crusts of the Magellan Seamounts in the western Pacific. |
| Key words: Magellan Seamounts cobalt-rich crust geochemistry occurrence phase |
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