九州-帕劳海脊南部13°20′N海山铁锰结壳关键金属富集规律及制约因素  

Enrichment and constraints of critical metals in ferromanganese crusts from 13°20’N seamount of the southern Kyushu-Palau Ridge

作　　者：黄威 胡邦琦[1,2] 宋维宇 赵京涛 路晶芳 孟祥君 江云水[1] 崔汝勇 丁雪 HUANG Wei;HU Bangqi;SONG Weiyu;ZHAO Jingtao;LU Jingfang;MENG Xiangjun;JIANG Yunshui;CUI Ruyong;DING Xue(Qingdao Institute of Marine Geology,China Geological Survey,Qingdao 266237,China;Laboratory for Marine Mineral Resources,Pilot National Laboratory for Marine Science and Technology(Qingdao),Qingdao 266237,China)

机构地区：[1]中国地质调查局青岛海洋地质研究所,青岛266237 [2]青岛海洋科学与技术试点国家实验室海洋矿产资源评价与探测技术功能实验室,青岛266237

出　　处：《海洋地质与第四纪地质》2022年第5期137-148,共12页Marine Geology & Quaternary Geology

基　　金：青岛海洋科学与技术试点国家实验室山东省专项经费(2021QNLM020003-2);国家自然科学基金面上项目“菲律宾海盆底层水体性质对中更新世气候转型的响应机制”(41976192);中国地质调查局地质调查二级项目(DD20221720,DD20191010)。

摘　　要：铁锰结壳富集Co、Cu、Mn、Ni、Ti、V、REE、Y和Zn等关键金属,研究其富集于结壳的规律以及相关地质环境制约因素对于未来开发利用这些海底金属资源十分重要。本文对九州-帕劳海脊南部13°20′N新发现的铁锰结壳样品进行了矿物学、元素地球化学和电子探针微区分析,发现其成分较为均一,未遭受明显的磷酸盐化作用,属于单层型水生成因结壳。Co、Ni等高含量关键金属主要富集在水羟锰矿内,其中主要以晶格态形式存在的Co所经历的表面氧化还原反应是其累积富集的关键;而Ni除了与Co一样通过置换Mn或占据晶格空位而呈现富集特征外,还大量以吸附态形式存在。Ti、V和REY等通过表面络合、晶格进入以及共沉淀作用富集在以六方纤铁矿为主的铁羟基氧化物组分内。Cu、Zn的晶格进入能力不足,加之海水Cu含量偏低,Zn的弱吸附作用共同导致它们以相对低含量形式分散分布。基于Co经验公式揭示结壳的形成起始于晚中新世,未出现明显生长间断,但持续生长时间不足导致结壳的关键金属累积富集程度低于全球主要结壳成矿区。不过,研究区理想的水深条件、较低的沉积速率、稳定的构造环境、合适的最小含氧带水深分布和远离非成矿物质的大规模稀释影响,都是本区结壳未来持续性增生和进一步富集关键金属的有利条件。Ferromanganese crusts are highly enriched in a wide variety of critical metals including Co,Cu,Mn,Ni,Ti,V,REE,Y,and Zn.Study of their enrichment in the crusts and the geological constraints is important for future development and utilization of them at seafloor.Recently,ferromanganese crust samples were acquired from 13°20 ′N seamount of the southern Kyushu-Palau Ridge,and analyzed in mineralogy and element geochemistry,as well as for electron probe microanalysis.Results show that the mineralogical and chemical composition of the samples are relatively uniform,and the crusts have not suffered from obvious phosphatization,which indicates that the crusts are characterized by one hydrogenetic crustal layer.Critical metals with high content such as Co and Ni are mainly enriched in vernadite.Co mainly exists in the lattice of vernadite due mainly to surface oxidation of vernadite.Ni is enriched in the crusts by replacing and occupying lattice vacancies of Mn as Co does,and a large amount of Ni exists in the form of adsorption.Ti,V,and REY are enriched in the iron oxyhydroxide components dominated by feroxyhyte by surface complexation,crystal lattice entry,and co-precipitation.Cu and Zn are lack of crystal lattice entry ability;the Cu content in seawater is very low and the adsorption of Zn is weak,thus resulting in their dispersed distribution and low content in the samples.This study reveals that the crusts started growing in the late Miocene and show no obvious growth break;the accumulated enrichment degree of critical metals in these samples is lower than that in the highest potential areas of the global ocean due to insufficient continuous growth time.However,the ideal water depth conditions,low deposition rate,stable tectonic environment,suitable water depth distribution of the oxygen minimum zone,and long distance from macroscale input of the non-metallogenic material into the study area are favorable for continuous growth and enrichment of critical metals in these crusts in the future.

关 键 词：铁锰结壳 关键金属 富集规律 制约因素 九州-帕劳海脊 

分 类 号：P736.4[天文地球—海洋地质]