黄威,胡邦琦,姜学钧,等. 九州-帕劳海脊13°20′N海山铁锰结壳生长过程中Si、Al、Ca的含量变化及对碎屑物质供给的指示[J]. 海洋地质与第四纪地质,2023,43(5): 26-35. DOI: 10.16562/j.cnki.0256-1492.2023070402
引用本文: 黄威,胡邦琦,姜学钧,等. 九州-帕劳海脊13°20′N海山铁锰结壳生长过程中Si、Al、Ca的含量变化及对碎屑物质供给的指示[J]. 海洋地质与第四纪地质,2023,43(5): 26-35. DOI: 10.16562/j.cnki.0256-1492.2023070402
HUANG Wei,HU Bangqi,JIANG Xuejun,et al. Variations in content of Si, Al, and Ca during the growth of ferromanganese crusts on the 13°20′N seamount of Kyushu-Palau Ridge and indication to the supply of detrital materials[J]. Marine Geology & Quaternary Geology,2023,43(5):26-35. DOI: 10.16562/j.cnki.0256-1492.2023070402
Citation: HUANG Wei,HU Bangqi,JIANG Xuejun,et al. Variations in content of Si, Al, and Ca during the growth of ferromanganese crusts on the 13°20′N seamount of Kyushu-Palau Ridge and indication to the supply of detrital materials[J]. Marine Geology & Quaternary Geology,2023,43(5):26-35. DOI: 10.16562/j.cnki.0256-1492.2023070402

九州-帕劳海脊13°20′N海山铁锰结壳生长过程中Si、Al、Ca的含量变化及对碎屑物质供给的指示

Variations in content of Si, Al, and Ca during the growth of ferromanganese crusts on the 13°20′N seamount of Kyushu-Palau Ridge and indication to the supply of detrital materials

  • 摘要: 作为深海铁锰结壳的重要组成部分,碎屑物质类型多样,不仅影响关键金属富集成矿,而且还可以指示结壳形成过程中的古海洋环境和重大地质历史事件。本文对九州-帕劳海脊13°20′N海山铁锰结壳样品进行了扫描电镜和激光剥蚀微区分析,并结合前期研究工作,发现大颗粒的碎屑物质主要由亚洲大陆风尘来源的石英、长石或两者的聚集体,以及主要分布在结壳外层的有孔虫壳体所组成,而细颗粒的碎屑物质包括陆源风尘沉降和周边岛弧物质风化搬运共同带入的黏土矿物,以及各种形态的生物体及其残片。结壳形成的早期其碎屑物质的供给量处于高峰阶段,晚期则降低到谷底,该趋势与Si、Al在结壳各层位中的含量分布特征一致,且可能有相当数量的细颗粒生物硅进入了铁锰氧化物纹层。结壳内早期被动增生的钙质生物体在中后期会遭受破碎和溶解,但其中的Ca并没有完全从结壳内迁移出去,而是大量被铁锰氧化物所吸附。结壳中的Ca主要赋存在细颗粒碎屑物质中,使得Ca在各层位全样样品和铁锰氧化物微区纹层中的含量极为相近,这与Si、Al的特征完全不同。研究区结壳样品属于典型开阔大洋海山型结壳,但因为受亚洲大陆风尘物质和硅藻供给的影响,其内部关键金属的富集在一定程度上受到了制约。

     

    Abstract: The detrital materials in diverse types are important components of deep-sea ferromanganese crusts. Detrital materials not only enrich the critical metals such as Co, Ni, Cu, Mn, REE and Y, but also record the oceanographic conditions and significant geological events during the growth of the crusts. Ferromanganese crust samples from the 13°20′N seamount of Kyushu-Palau Ridge were studied in detail using scanning electron microscopy and laser ablation-inductively coupled plasma-mass spectrometry based on previous research works. Results reveal that the large grain detrital materials in the samples are composed of mainly the aggregates of quartz and feldspar, and the foraminiferal fossils are mainly distributed in the outer part of the samples. The fine grain detrital materials include clay minerals, various forms of the fossil organisms and their fragments. The quartz and feldspar within the crusts are mainly derived from the Asian continental eolian dust, while the clay minerals are supplied by the eolian dust from the Asian continent and the weathering material from the surrounding island arc. The supply of detrital materials is at a high peak stage in the early stage of crust formation while it decreases to the lowest point in the later stage, which is consistent with the distribution characteristics of Si and Al contents in every part of the crusts, and a considerable amount of biogenic silica nanofossils may have incorporated into the ferromanganese oxide microlayers. The passively accreted Ca biogenic material within the crusts in the early stage suffers from fragmentation and dissolution in the middle and late stages, but the Ca in the inner part does not migrate out of the crusts completely. It is instead adsorbed by ferromanganese oxide microlayers in large quantities. The Ca contents in the bulk parts and the ferromanganese oxide microlayers are very similar to those in the three parts of the crust samples, which is due probably to that Ca in the crust is mainly distributed in fine grain detrital materials. The contents characteristics of Ca is completely different from Si and Al. The crust samples in the study area belong to normal open oceanic seamount-type crusts, but the enrichment of these critical metals is constrained by the supply of eolian dust from the Asian continent and the diatom from the surrounding seas.

     

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