Study on the manganese nodule V. Thermal studies of the iron-manganese phase

The thermal phase transformation of the iron-manganese phase of the Pacific Ocean manganese nodules were studied by the differential thermal and X-ray diffraction methods. X-ray powder patterns of the heated samples at the temperature of 600°C to 1000°C show the occurrence of hematite, bixbyite and cubic and tetragonal (Fe, Mn)₃O₄. Bixbyite produced by the heat treatment of the iron-manganese phase gives an abnormal X-ray pattern in comparison with the standard sample of bixbyite. Cubic (Fe, Mn)₃O₄ is produced not only by the reaction of bixbyite with hematite over 900°C, but also at the lower temperature, such as 600°C. While, tetragonal (Fe, Mn)₃O₄ is a reaction product of cubic (Fe, Mn)₃O₄ with bixbyite over 900°C in the case of manganese rich nodules. The species and quantities of the products after the heat treatment are assumed to be mostly influenced by the relative contents of iron and manganese in the manganese nodule.     

东太平洋中国多金属结核区锰结核样品中微生物群落结构的研究

通过非培养手段研究了东太平洋中国多金属结核区ES0303站点锰结核样品中的微生物群落结构.细菌16S rRNA基因克隆文库的研究结果表明：结核内细菌种群结构复杂,微生物种类丰富且各种群丰度不一（61个OTUs）,其中变形杆菌类群为优势种群,占所有细菌克隆子比例的64%,且主要分布于β/γ-、α-和δ-等3类变形杆菌（Proteobacteria）亚群之中,占比分别为34%、18%和12%.此外还存在包括酸杆菌（Acidobacteria）,放线菌纲（Actinobacteria）,绿弯菌门（Chloroflexi）,厚壁菌门（Firmicutes）,浮霉菌门（Planctomycetes）等在内的细菌类群的分布,克隆子比例依次为9%、7%、8%、2%和5%.古菌16S rRNA基因克隆文库的研究结果表明：古菌的群落结构单一（仅12个OTUs）,全部是由泉古菌海洋类群I（crenarchaeote marine group I,MGI）组成;其中MGI-η类群最为丰富,达到44%,而MGI-α、MGI-ζ和MGI-ε类群的克隆子比例分别为25%、18%和9%,另外还发现2个新的MGI分类类群.相关克隆子的数据库比对和系统发育树分析表明,并未发现已报道的直接参与铁锰氧化还原相关类群的存在,但它们大多数与来自多金属结核来源或深海来源的不可培养微生物具有较高的同源性.进一步的分析表明,锰结核内存在相当数量的氨氧化菌、硫酸盐还原菌、酸杆菌等能够改变pH值的细菌和古菌类群的存在,意味着它们可能在锰结核的形成过程中起到重要的作用.     

The influence of the pycnocline on the oceanic settling of manganese nodule mining waste

The likelihood that manganese nodule mining discharge (essentially deep-seabed clays and some nodule fragments) would reside on the pycnocline for a long period of time was investigated by introducing mining waste particles into a two-layer laboratory settling column illuminated by laser. The experiments were repeated with polystyrene particles of uniform shape and size to further study the effect of a density interface on settling. The results indicate that mining particulates do not have sufficiently low density to accumulate on the pycnocline although a density interface can temporarily concentrate settling particles. A review of related studies of accumulation of inorganic particles on density interfaces suggests that the available evidence for pycnocline accumulation of inorganic particles is slight. A measurement of the wet density spectra of any oceanic discharge is necessary to accurately assess the possibility of particles rafting on a density surface.     

Possibilities of using the GLORIA system for manganese nodule assessment

The I.O.S. long range side-scan sonar GLORIA has been widely used over a variety of seabed types, but until recently had not been used over an independently authenticated field of manganese nodules. In the Eastern Atlantic Ocean at approximately 31°25 N 25°15 W, a field of nodules approximately 3–6 cm in diameter covering up to 18% of the seafloor was observed using an underwater camera. The nodule field occurred over approximately 2.8 km of the 8.3 km camera run. The corresponding GLORIA image shows an area of medium intensity backscattering, approximately 3.7 km in diameter. Considering the likely contrast in acoustic reflectivity between manganese nodules and deep sea sediments, we propose a correlation between the nodules observed in the photographs and the medium intensity echo target revealed by the GLORIA system.     

深海多金属结核水力集矿头流场结构数值模拟研究

深海蕴藏着丰富的多金属结核资源,受海水深度等限制,结核采集目前仍存在巨大挑战。水力式采矿具有结构简单、可靠性高的优势,是目前最具发展前景的采集方式之一。水力式采矿通过水流动力进行结核采集,喷射形成的复杂流场结构直接影响海床上结核颗粒剥离、起动、采集效率和海洋环境扰动强度,采集器离地高度、喷嘴射流角度和速度等具有较大优化空间。基于计算流体力学数值模拟研究了集矿头附近三维水流结构,分析了喷嘴射流速度和结核粒径对局部流场、床面剪切力以及结核采集能效的影响。结果表明：集矿头周围流场存在典型分区结构,包括淹没射流区、冲击区、壁面射流区、汇合区和上升区;随着喷射流速增大,最大床面剪切力近似线性增长,结核有效起动面积指数增长;随着结核粒径增大,有效起动面积减小,结核采集能效降低;综合考虑结核采集强度和采集能效,建议采集器喷射流速取8～9 m/s。     

Submersible observations of manganese nodule and crust deposits on the Tenpo Seamount,Northwestern Pacific

Pavements of manganese nodules and crusts and outcrops of Miocene limestones were observed on the flanks and flat top of the Tenpo Seamount during three Shinkai 2000 dives. The pre‐Miocene volcano supplied nuclei of volcanic rocks and hydrothermal manganese deposits, and subsequent slow or no sedimentation promoted deposition of abundant hydrogenetic nodules and crusts, mainly on the upper flank of the seamount. Nodule pavements generally cover calcareous sand surface sediments, while crusts cover hard outcrops composed probably of volcanic rocks. The fields of crusts and nodules are sparsely distributed with each other on scales of meters to tens of meters. The on‐site observation suggests the deposits have encountered tectonic and/or mass movements that resulted in unusual occurrences of densely stacked nodules and occasionally the nodules resting directly on crusts or hard substrates. Mineralogical and chemical compositions reveal that for nodules and crusts the encrusting manganese layers of around 1 cm thickness are composed of hydrogenetic vernadite, and diagenetic influence is negligible.     

Ocean manganese nodule and sediment reference materials

In this article, sampling locations, sample types, sample processing methods, and certified values of ocean manganese nodule and sediment reference materials available throughout the world are briefly described. Recommended or information values of major, minor, and trace constituents in those samples have also been collected, and a review of the main characteristics of their property values is presented.     

大洋多金属结核矿区沉积物土工性质

利用1994年大洋多金属结核调查所获得的土工资料,结合以往有关资料进行了综合分析。研究了大洋沉积物类型、沉积物土工性质、土质强度等,为未来海底工程设施和多金属结核开采设备的设计与制造提供依据。     

Large phillipsite crystal as ferromanganese nodule nucleus

We report here the occurrence of, to date, the largest (21 × 10 × 8 mm) phillipsite crystal forming the nucleus of a diagenetically formed ferromanganese nodule from the Central Indian Ocean Basin (CIOB). Assuming an average rate of ferromanganese nodule accretion as ~ 2 mm/Ma and that of phillipsite growth as ~ 0.65 mm/Ka, the nucleus material appears to have been growing for ~4.5–5 Ma. Originally surfaced as a rock fragment from late Miocene volcanism, this nucleus was later altered to phillipsite under alkaline, silica-undersaturated, low-temperature conditions through the length of the Neogene sedimentary hiatus.     

Manganese nodule formation in the Pacific Ocean: a general theory

An attempt is made to outline a satisfactory general theory for the formation of Pacific deep-sea manganese nodules based on a consideration of the time of initiation of formation of the nodules, a mechanism of maintenance of the nodules at the sediment surface and the role of biological productivity of the surface waters in influencing nodule characteristics. Using this model, the principal physical, chemical and distributional features of the nodules and reasons for their differences on a regional scale in the Pacific can be interpreted.     

Relationship between polymetallic nodule genesis and sediment distribution in the KODOS (Korea Deep Ocean Study) Area, Northeastern Pacific

Polymetallic nodule and sediment characteristics were investigated for two blocks (KR2 and KR5) in the Korea Deep Ocean Study (KODOS) area in order to better understand nodule distribution and the potential effects of sediments on nodule genesis. The northern block (KR2) is dominated by hydrogenetic nodules, whereas the southern block (KR5) is dominated by diagenetic nodules. Sediments in the study area are assigned to three major lithologic units which are distinctive in color and texture. The northern block is characterized by a thick, metalpoor Unit 1 sediment, which is thin in the southern block, where metal-rich Units 2b and 3 occur close to the surface. The distribution of different nodule genetic types in the northern and southern blocks can be attributed to topographic variations (topographic high near seamounts in KR2 and abyssal plain in KR5) and different sedimentation rates (0.1 and 0.32 mm/kyr in blocks KR2 and KR5, respectively). The southern block has a geologic setting more conducive to diagenetic nodule formation, such as flat topography and sediment composition. Nodule distribution in the studied blocks might also be explained by the distribution of the sediment units of different metal contents. The northern block, in which Unit 1 is thicker, has more abundant hydrogenetic nodules, possibly because Unit 1 prevents metals that are remobilized from the underlying sediments from reaching the seabed where the nodules are forming.     

Manganese nodule distribution in different topographic domains of the Central Indian Basin

Manganese nodule distribution is primarily influenced by seafloor topography. Nodule distribution at 479 locations vis‐à‐vis seabed topography is studied by superimposing sampling location on the topographic profile and assigning appropriate domain (hilltop, valley, slope, or plain) for the sampling location. Highest mean abundance is observed at the valleys (6.94 kg /m²), followed by hilltops, slopes, and least on plains. Frequency distributions are regular (Gaussian) on plains, whereas on valleys and hilltops they are irregular (Rayleigh type). Fe and Co content is highest in nodules from hilltops and lowest in those from plains. Conversely, Mn, Cu, and Ni content is highest on plains and least on valleys. Fe: Mn and Co: Mn are negatively correlated in all the domains. Mn and total metal content (Ni + Cu + Co) show direct relationship in all the domains. An inverse relation between nodule abundance and composition is found. Cluster analysis on chemical and abundance data shows two distinct groups in all domains. Abundance and Fe and Co content typically form one group, while all other elements form another group. Genesis of nodules depends on the availability of supply of transition elements to the abyssal environment, maintenance of nodules in the sediment‐water interface, and sedimentation rates.     

Energy dispersive X-ray analysis of the surface of a deep-sea ferromanganese nodule

In an effort to elucidate the mechanism of formation and accretion of ferromanganese nodules, transverse sections of undisturbed botryoid surfaces of nodules from the abyssal central North Pacific were examined by X-ray analyses both by multiple replicate sample transects and mapping. Surface concentrations of Mn and Fe were found of the size and shape of microorganisms. Abundant microorganism-like objects covering the surface and the apparent absence of Si (i.e. no sediment) with the Mn and Fe concentrations suggests microorganisms may be involved either in the selective accretion or removal of these metals. If metal accretion was simply physicochemical, one would expect a more or less even distribution of Mn and Fe on the botryoid surfaces.The replicate X-ray sample transects showed that Mn and Fe have a distribution corresponding to botryoid zonation. Areas of high Mn X-ray intensity were found associated with the cap and equatorial zones of the botryoid. Most of the valley zone of the botryoid show a more or less even Mn distribution and an increase in Fe X-ray intensity. At the base of the botryoid both metals apparently precipitously decrease.     

东太平洋铁锰结核区微生物的丰度及其成矿作用研究

１９９４ 年 ４～１１ 月在东太平洋铁锰结核区, 使用 “向阳红 ０９”船, 采集 ３９ 个表层沉积物、１２ 个上覆水和 ７ 个结核样。在现场用平板法测定了异养细菌和铁、锰细菌丰度, 用稀释法（ Ｍ Ｐ Ｎ 法） 测定硫酸还原菌丰度。为了探讨微生物在大洋成矿过程的作用, 在实验室对异养细菌和锰细菌作纯化分离, 并进行了多项生理生化实验, 参照伯杰氏手册第八版鉴定至属。使用分光光度法, 测定锰细菌对锰、铁离子的转化作用, 使用 ｐ Ｈ 计测定了ｐ Ｈ 值的变化, 同时测定了不同培养温度对转化作用的影响。结果表明, 沉积物中异养细菌的数量在 ３×１００～９５×１０３个／ｇ; 锰、铁细菌的数量在１×１００ ～１×１０３ 个／ｇ; 硫酸盐还原细菌的数量分布范围在 ０～４×１０３个／ｇ;在上覆水和结核样中各类细菌的数量均较低,比沉积物样中各类细菌数低 １ 个数量级。在细菌的种群组成方面与近海区相比存在差异, 特别是在革兰氏阳性菌的组成上微球菌占了绝对优势。在成矿作用方面, 锰细菌对锰、铁氧化还原的实验结果表明, 在好氧的条件下, 锰细菌使可溶性的 Ｍ ｎ２＋ 氧化为 Ｍ ｎ４＋ , 其氧化速度与环境温度存在密切关系, 锰细菌对铁的氧化速度比对锰的氧化速度来得快。在     

东太平洋CC区板块构造和多金属结核资源效应探讨

利用东太平洋CC区多波束海底地形测量、结核覆盖率深拖系统探测、结核丰度地质采样和地球物理地震勘探资料,运用板块构造和沉积动力学理论,并与丰度趋势面和神经网络分析结果对比,对东太平洋CC区构造与多金属结核资源效应关系进行了探讨,并认为:(1)富集在研究区约200亿t结核的最主要控制因素是东太平洋海隆、莱恩山脉、克拉里昂-克利伯顿大断裂(Clarion-Clipperton Fracture Zone),东、西、南、北的四个构造单元为结核大量富集起到了框架性的关键作用;(2)本区经历了和遵循着海底扩张的基本过程,这个过程对结核物质来源、成矿作用、结核分布有重大影响,结核丰度、覆盖率与地形变化非常一致,重大相变距离为10～15km,基底自形成以来一直影响着地表结核;(3)地球深部地质作用过程对结核成矿作用也有一定影响,影响因素可能涉及基底岩浆房及其大小等.     

Optimum sampling interval for evaluating ferromanganese nodule resources in the central Indian Ocean

A study to estimate manganese nodule abundance (weight of nodules in kg/m²) was carried out in a small area of the abyssal plains covering a one-degree square block in the central Indian Basin. Abundance was assessed at various intervals by progressively reducing the grid spacing. Sampling the corners of the 1° survey block (approximately110-km spacing), i.e., four stations with 5-7 free-fall operations (sampling locations) in each case, indicated a nodule abundance of 3.50 kg/m². By reducing the sampling spacing to four grid units (0.5° survey blocks) and sampling the entire block at eight stations (25 locations), the average abundance of the block was 3.36 kg/m². Further reduction of the grid to 0.25° survey blocks and sampling in 16 grid units (70 sampling locations) increased the abundance to 4.41 kg/m². For 64 grid units in the one-degree block (sampling in 0.125° survey blocks), a substantially higher value was recorded, i.e., 5.31 kg/m² or about 1.5 times the abundance obtained at a 1° spacing. Adding 25 more stations in 0.0625° survey blocks (intervals of sampling locations approximately 500 m) resulted in a negligible change in abundance, the average value of the one-degree block being 5.23 kg/m². These data demonstrate that, for estimating nodule resources in the region, it is important to adopt a close-grid sampling strategy, so that areas with lower abundance can be relinquished and areas with higher abundance can be confidently identified. To ascertain exact nodule abundance for mine-track selection, it may be sufficient to restrict detailed grid surveys to areas with marked variations in topography and nodule abundance, rather than carrying out such detailed (albeit less cost effective) surveys at a very narrow spacing (0.0625°) over the entire pioneer area.     

东太平洋多金属结核的一般特征与影响因素

本文主要阐述了东太平洋海盆国家海洋局调查区内多金属结核的物性特点、形态分区、粒级分布、矿物成分以及结核丰度、品位与生成环境因素的关系，并指出了勘探与选冶的较佳区块。     

大洋多金属结核矿区表层沉积物的物理性质

利用大洋多金属结核矿区调查过程中4个航次所得的600多组表层沉积物物性测试资料,将矿区的沉积物分为5种类型,并分析了这些沉积物的物理性质,同时,运用回归分析方法,统计分析了不同类型沉积物的含水量、湿密度、孔隙比与埋藏深度的关系,以及各物性指标之间的相关关系。结果表明:(1)大洋多金属结核矿区表层沉积物均为粉质土,黄棕色粉质土是西部矿区的主要沉积物类型,棕黄色粉质土是东部矿区的主要沉积物类型;(2)除褐色粉质土外,其余4种类型土的含水量、孔隙比均随埋藏深度的增加而减少和降低,湿密度则随深度增加而增大;(3)各类土的物性指标与埋藏深度的相关性甚好,因而可以利用埋藏深度对矿区的沉积物进行物性指标预测;(4)含水量、孔隙比、湿密度等物性指标之间呈线性相关,其中含水量与孔隙比的相关性最为密切,呈明显线性关系。