机构地区:[1]自然资源部海底矿产资源重点实验室,广州海洋地质调查局,广州510075 [2]中国地质大学(北京),北京100083 [3]南方海洋科学与工程广东省实验室(广州),广州511458
出 处:《海洋地质与第四纪地质》2023年第3期119-131,I0007-I0010,共17页Marine Geology & Quaternary Geology
基 金:国家自然科学基金地质联合基金“西太平洋多类型深海表生沉积矿产关键金属元素富集机制与成矿系统”(U2244222);南方海洋科学与工程广东省实验室(广州)人才团队引进重大专项项目“西太平洋富稀土沉积物、富钴结核成矿机制及其时空关系研究”(GML2019ZD0106);国家自然科学基金“西太平洋富稀土沉积物中的磷酸盐组分及其物源研究”(42002085),“稀土在碳酸岩岩浆源区的富集及其动力学背景”(92162216),“西太平洋典型海山地形下的海洋多尺度相互作用及其成矿效应”(91958202)。
摘 要:西太平洋深海盆地同时发育多金属结核和富稀土沉积物,但针对多金属结核及其表层沉积物之间关系的研究较少。通过多金属结核-表层沉积物地球化学分析,揭示关键金属元素在结核、沉积物中的富集和分馏过程,探讨沉积过程与环境对多金属结核生长的影响。研究区多金属结核具有相对高的Co、REY含量,低的Mn/Fe比值,显示为典型的水成成因。主成分分析及相关性分析结果指示结核的成矿过程是在水成作用、成岩作用以及陆地碎屑、生物碎屑输入的作用下,Fe-Mn氧化物对海水及孔隙水中各类金属元素的选择性富集。研究区表层沉积物主要为深海黏土,相较于多金属结核富集大部分金属元素,深海黏土更为富集Si、Al、Na、K等元素。沉积物中Co、Ni、Cu等金属元素的富集与Fe-Mn微结核的含量相关,而REY与磷酸盐组分更为密切。Fe-Mn氧化物组分对海水中金属元素选择性吸附形成多元素的富集及显著的Ce正异常、Y负异常,而磷酸盐组分主要继承海水的稀土特征,它们的含量决定了沉积物中金属元素及稀土元素的含量和模式。结核及沉积物在关键元素富集的过程中有相似的过程,Fe-Mn氧化物组分是二者元素富集过程的载体。研究区的低生物生产力和低沉积速率,导致海水中相关元素的沉降通量减少、沉积速率减慢,为水成型结核生长提供有利条件。受到南极底流的影响,研究区底层海水具有富氧特征,且在其强底流冲刷作用下造成了频繁的沉积间断,促进了铁锰氧化物的形成和关键金属元素的富集。Polymetallic nodules and rare earth-rich sediments are developing simultaneously in the western Pacific Deep Sea Basin,but there are few studies on the relationship between polymetallic nodules and their surface sediments.In this study,the geochemical analysis of polymetallic nodules and surface sediments was used to reveal the enrichment and fractionation processes of critical metal elements in nodules-sediments and to explore the influence of deposition processes and environment on the growth of polymetallic nodules.The polymetallic nodules in the study area have relatively high Co and REY contents and low Mn/Fe ratios,indicating a typical hydrogenetic precipitation.The results of principal component analysis and correlation analysis indicate the nodule formation process is a selective enrichment of Fe-Mn oxides for various metal elements in seawater and pore water under the influence of hydrogenesis,diagenesis and input from terrestrial debris and bioclastic.The surface sediments in the study area are mainly deep-sea clays,which are more enriched in Si,Al,Na,K,and other elements than the polymetallic nodules,which are enriched in most metal elements.The enrichment of metallic elements such as Co,Ni,and Cu in the sediments is related to the content of Fe-Mn micronodules,while REY is more closely related to the phosphate fraction.the Fe-Mn oxide fraction selectively adsorbs metallic elements in seawater to form multi-element enrichment and significant positive Ce anomalies and negative Y anomalies,while the phosphate fraction mainly inherits the rare earth characteristics of seawater,and their content determines the content and pattern of metallic elements and rare earth elements in the sediments.The nodule and sediments have similar processes in the enrichment of critical elements,and Fe-Mn oxide components are the carriers of elemental enrichment processes in both.The low biological productivity and low sedimentation rate in the study area result in reduced sedimentation fluxes and slower sedimentation rates o
正在载入数据...
正在载入数据...
正在载入数据...
正在载入数据...
正在载入数据...
正在载入数据...
正在载入数据...