劳盆地热液羽状流颗粒物微区特征及指示意义

Micro-Area Characteristics and Implications of Hydrothermal Plume-Derived Particles in Lau Basin

以劳盆地热液羽状流水体为研究对象,对6个不同深度水层(海底以上50～500m)的悬浮颗粒物(>0.45μm)进行了扫描电镜观察和X射线能谱分析。通过颗粒物的微形貌将颗粒物分为生物碎屑、微生物成因颗粒、无定形颗粒和自形颗粒等类型。微生物成因颗粒包括丝状体和簇状体等形态类型;自形颗粒主要为黄铁矿和闪锌矿晶体;根据颗粒组分特征将无定形颗粒分为S-Zn-Ba-Ca、Fe氧化物+少量Ba-Zn-Ca、Fe-Mn-Ca-Ba+少量的Zn、硫化物颗粒及多金属颗粒5种不同类型。大量与热液活动有关的颗粒类型的出现以及无定形颗粒的尺寸分布特征反映了研究站位处于热液羽状流的早期发育阶段,推测在附近几百米范围内存在活动的热液喷口区。

Particulate samples（〉0.45 μm） from a hydrothermal plume in Lau basin are collected by filtering on deck and analyzed by scanning electron microscope（SEM） and X-ray energy dispersive spectroscopy（EDS）.Four types of particles have been morphologically characterized.i）Biogenic detritus mainly device from background water.ii）Microbial particles include filamentous and clustered configuration;and these specific morphology suggest specific microorganism community.iii）Amorphous particles are divided into S-Zn-Ba-Ca phase,Fe-oxide phase containing trace of Ba-Zn-Ca,Fe-Mn-Ca-Ba phase containing trace of Zn,sulfide particles and polymetallic particles,and the amorphous forms should originate from precipitation in the external part of sulfide chimney or the fragmentation of chimney rocks.iv） Automorphic particles are probably formed in an area where the chemical conditions are homogeneous,i.e.the internal part of sulfide chimney.So many particles related to hydrothermal activity and the distributions of amorphous particles in different water layers indicate that our study station locats at the incipient stage of formation of hydrothermal plumes,and during the several hundreds meters there may exist an active hydrothermal vent area.