任江波, 何高文, 姚会强, 邓希光, 朱克超, 杨胜雄. 磷酸盐化作用对富钴结壳中稀土元素的影响[J]. 海洋地质与第四纪地质, 2017, 37(2): 33-43. DOI: 10.16562/j.cnki.0256-1492.2017.02.004
引用本文: 任江波, 何高文, 姚会强, 邓希光, 朱克超, 杨胜雄. 磷酸盐化作用对富钴结壳中稀土元素的影响[J]. 海洋地质与第四纪地质, 2017, 37(2): 33-43. DOI: 10.16562/j.cnki.0256-1492.2017.02.004
REN Jiangbo, HE Gaowen, YAO Huiqiang, DENG Xiguang, ZHU Kechao, YANG Shengxiong. THE EFFECTS OF PHOSPHATIZATION ON THE REY OF CO-RICH FE-MN CRUSTS[J]. Marine Geology & Quaternary Geology, 2017, 37(2): 33-43. DOI: 10.16562/j.cnki.0256-1492.2017.02.004
Citation: REN Jiangbo, HE Gaowen, YAO Huiqiang, DENG Xiguang, ZHU Kechao, YANG Shengxiong. THE EFFECTS OF PHOSPHATIZATION ON THE REY OF CO-RICH FE-MN CRUSTS[J]. Marine Geology & Quaternary Geology, 2017, 37(2): 33-43. DOI: 10.16562/j.cnki.0256-1492.2017.02.004

磷酸盐化作用对富钴结壳中稀土元素的影响

THE EFFECTS OF PHOSPHATIZATION ON THE REY OF CO-RICH FE-MN CRUSTS

  • 摘要: 稀土(REY)是一组有效示踪物质源区和地质过程的元素,本研究利用X荧光光谱法(XRF)和电感耦合等离子光谱仪(ICP-MS)分析了马尔库斯-威克海山和中太平洋海山富钴结壳的主要元素和稀土元素,结合前人研究成果对比了磷酸盐化及未磷酸盐化富钴结壳的稀土特征。结果显示:磷(P)含量低的结壳具有相对低的稀土总量(∑REY),北美页岩标准化后显示铈(Ce)正异常和钇(Y)负异常;磷酸盐化后的结壳具有相对高的∑REY,并表现出Ce正异常和显著Y正异常。磷酸盐化结壳中应存在“富稀土磷酸盐”组分,特别是对Y具有重要贡献。将磷酸盐化结壳视为磷酸盐组分和结壳组分的混合,模拟结果显示富稀土磷酸盐组分具有海山磷块岩的稀土配分模式,但是其∑REY达到普通磷块岩的10倍或以上。考虑到海洋中富钙沉积物丰富,大量PO43-不同程度地交代碳酸盐等钙质物质,容易形成贫稀土磷酸盐。而伴随结壳缓慢的成矿过程,部分磷酸盐的形成未受到碳酸盐的影响,容易形成富稀土磷酸盐。

     

    Abstract: Rare earth elements and yttrium (REY) are extremely coherent in the nature. The relative abundances of them can be used to deduce their sources or subsequent geological processes. Major elements and REY of the Co-rich Fe-Mn Crusts from Marcus-Wake Seamounts and Mid-Pacific seamounts are analyzed by XRF and ICP-MS. Combined with previous studies, REY characteristic of phosphatized and non-phosphatized Fe-Mn Crusts are emphasized respectively. Fe-Mn Crusts with low P have low ΣREY and notably positive Ce anomaly, as well as negative yttrium anomaly, after normalized by the North American shale composite(NASC). While Fe-Mn Crusts with high P have relatively high ΣREY, positive Ce anomaly and notably positive yttrium anomaly normalized by NASC. There must exist REY-rich phosphate components in the phosphatized Co-rich Fe-Mn Crusts, which are especially rich in yttrium. The issue of phosphatized crusts could be regarded as a mixed model of phosphate components and Fe-Mn crust components. Mixed model simulating result indicates that REY-rich phosphate components in Fe-Mn Crusts have the same REY pattern as seamount phosphate rock, but the content could be more than 10 times over that of seamount phosphate rock. Besides REY3+ and Ca2+, other alkali-earth metal ions can also be bound to PO43- in water column, and there are numerous calcareous sediments in ocean, PO43- can replace CO32- in carbonate sediments to form REY-poor phosphate. However, the growth of the Fe-Mn Crust is so slow that REY has a better environment to compete with Ca at the time of PO43- input, forming dissemination REY-rich phosphate. Although PO43- is still mainly bound with Ca2+ in REY-rich phosphate, ΣREY/Ca ratio increases remarkably. This REY enrichment model may be a common geological process in non-calcium sediments in deep sea.

     

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