西南太平洋劳盆地东北部火山岛弧热液区羽流中Zn形态分布特征  

The characteristics of Zn species in hydrothermal plumes above arc volcanoes in the Northeast of Lau Basin,Southwest Pacific Ocean

作　　者：宋江 王文朋 王虎[1] SONG Jiang;WANG Wenpeng;WANG Hu(State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092

出　　处：《海洋地质与第四纪地质》2025年第1期122-135,共14页Marine Geology & Quaternary Geology

基　　金：国家重点研发计划“深海勇士号能力提升及科学应用”(2022YFC2805504);国家自然科学基金项目“西太平洋劳盆地火山岛弧热液羽流区铜同位素组成及其演化”(42376066)。

摘　　要：海底热液流体富含多种金属元素,可能是海洋中金属元素的重要来源之一。对西南太平洋劳盆地东北部火山岛弧两种不同类型热液系统(水岩反应形成的高温热液系统和受岩浆挥发份影响的低温热液系统)羽流中Zn元素的形态进行了分析,包括颗粒态(pZn)、溶解态(dZn)和胶体态Zn(cZn)。结果表明由于水岩反应形成的高温热液流体中H2S浓度较高,导致热液羽流中含有较高浓度的pZn,其最高浓度可达16.9 nM,受岩浆挥发份影响的低温热液流体中H2S浓度较低,羽流中pZn浓度亦相对较低,但仍然高于背景海水,即使在扩散至距West Mata海山喷口5千米以外的羽流中,pZn浓度仍然可达3.1 nM,表明热液喷发的pZn并没有快速沉淀,而是可以随羽流在海洋中扩散,海底热液系统可能是海洋中pZn的重要来源。羽流中dZn的分析结果表明,两种不同类型的热液区羽流中dZn浓度并无显著差别,且由于热液的输入导致部分羽流样品中dZn浓度高于背景海水,同时由于颗粒态铁的吸附作用,亦导致部分羽流样品中dZn浓度低于背景海水,因此热液羽流可能是海洋中dZn的源或汇。扫描电镜和能谱分析结果表明火山喷发可能是羽流中cZn的重要来源。Seafloor hydrothermal fluids are rich in various metal elements and could be one of the important sources of metals in the ocean.We investigated Zn species in hydrothermal plumes in different types of hydrothermal systems(water-rock and magmatic-hydrothermal systems)in the northeastern Lau Basin,Southwest Pacific,including particulate Zn(pZn),dissolved Zn(dZn),and colloidal Zn(cZn).Results show that the plumes contained higher pZn concentrations than background seawater(typically<0.5 nM)in maximum of 16.9 nM.In plumes from lowtemperature magmatic-hydrothermal systems,pZn concentrations were comparatively low,but still higher than that in background seawater.Even in the plumes that originated from low-temperature venting at West Mata that had dispersed off to over 5 km,the pZn concentration could still reach 3.1 nM,which indicates that pZn did not precipitate rapidly but dispersed in the ocean with the plumes,and the seafloor hydrothermal systems could be one of the sources of pZn in the ocean.The analyses of dZn in the plumes revealed no significant difference in dZn concentration between the two types of hydrothermal systems.Although the input of hydrothermal fluids resulted in higher dZn concentrations in some plume samples compared to background seawater,the adsorption by particulate Fe led to lower dZn concentrations in other plume samples.Therefore,hydrothermal plumes could act as either a source or a sink of dZn in the ocean.Observations in scanning electron microscopy and energy-dispersive X-ray spectroscopy suggest that the cZn in plumes could be from volcanic eruption.

关 键 词：Zn形态 热液羽流 火山岛弧 劳盆地 

分 类 号：P736[天文地球—海洋地质]