Annotated record and chemical analyses of a polygenetic manganese nodule (slab) from the Scott Plateau, Indian Ocean (core VA-16-13KD)

A large manganese nodule (manganese slab) was dredged from 2100 m on the Scott Plateau by R.V. Valdivia in 1977. It is an irregular ellipsoid, with a maximum dimension of 28 cm, parallel to the sea floor. Chemical analyses show that Mn and Fe proportions are comparable, and total Ni + Cu + Co content averages 0.7%. The nodule has a complex growth history which started with radial upward growth leading to coalescing into a continuous crust. The crust was coated with horizontal layers. After fracturing and infilling of cracks with calcareous sediment, further layers encased the nodule.1977年，研究船瓦尔迪维亚号（R.V. Valdivia）于斯科特高原（Scott Plateau）水深2100米处拖网采集到一枚大型锰结核（manganese nodule，又称锰块manganese slab）。该样品呈不规则椭球体，最大轴向尺寸为28厘米，其长轴平行于海底。化学分析结果显示，锰（Mn）与铁（Fe）的占比相当，镍（Ni）、铜（Cu）、钴（Co）的总含量平均值为0.7%。该锰结核具有复杂的生长演化历程：初始阶段以放射状向上生长，最终汇聚形成连续壳层；该壳层覆有水平层理结构。后续其发生断裂，裂缝被钙质沉积物充填，随后又有新的层状物包裹该结核。