摘要
以冲绳海槽伊平屋北热液区附近两个站位(HOBAB2-T3和HOBAB2-T6)的浮岩为研究对象,分别对充填沉积物的浮岩(T3-D、T6-D)和去除沉积物的浮岩(T3-C、T6-C)进行扫描电镜观察、矿物组成和微量元素组成的对比分析。结果表明,浮岩气孔充填的沉积物主要来源于冲绳海槽内碎屑沉积物的混入,其中气孔较小的T3浮岩中充填的沉积物组成主要为伊利石和石英,而气孔较大的T6浮岩中充填的沉积物组成主要为石英和长石,代表了海槽内沉积物的一般矿物组成。邻近热液区的T3浮岩气孔中的沉积物含有异常高含量的Pb(>101μg/g)、Zn(>196μg/g)、Cu(>47μg/g)等金属元素,代表强烈的热液活动信号;距热液区稍远的T6浮岩气孔中沉积物也表现出Pb、Cu等元素含量的异常特征,可能代表较弱的热液活动信号。这说明海底热液区附近的浮岩气孔中充填的沉积物可以记录热液活动的信息,这对寻找浮岩分布区新的热液活动具有重要的指示意义。
The pumices samples from HOBAB2-T3 and HOBAB2-T6 near the Iheya North hydrothermal field,Okinawa Trough（OT）are divided into two groups.One group（T3-C and T6-C）was carefully cleaned to remove any sediment filled in vesicles,while the second group（T3-D and T6-D）remained unchanged.To qualitatively understand the mineral and chemical compositions of the sediment fillings in pumice＇s vesicles,each group of pumices was examined by scanning electron microscope（SEM）and their mineralogy and trace elemental compositions were analyzed and compared.Results show that the sediments in pumices are mainly from OT clastic deposits.Vesicles in T3 pumice are smaller and they are mainly filled by illite and quartz in terms of mineral compositions.However,sediments in larger vesicles of T6 pumice are dominated by quartz and feldspar,same as the minerals in OT in general.The sediments in T3 pumice,adjacent to the hydrothermal field,however,contain extremely high concentrations of Pb（101μg/g）,Zn（196μg/g）,and Cu（47μg/g）,indicatingstrong hydrothermal activities.For T6 pumice that is slightly farther away from the hydrothermal field,the sediment fillings also exhibit anomalies in Pb and Cu,which might stand for relatively weaker hydrothermal signal.The above indicates that sediments in pumice＇s vesicle near the hydrothermal field may record information of hydrothermal activity,which has great significance in exploring new hydrothermal filed in the region with pumiceous volcanic rocks.
作者
张玉祥
曾志刚
殷学博
李禾
齐海燕
王晓媛
陈帅
ZHANG Yuxiang;ZENG Zhigang;YIN Xuebo;LI He;QI Haiyan;WANG Xiaoyuan;CHEN Shuai(Key Laboratory of Marine Geology and Environment,Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China;University of Chinese Academy of Sciences,Beijing 100049,China;Laboratory for Marine Mineral Resources,Qingdao National Laboratory for Marine Science and Technology,Qingclao 266071,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China)
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
2018年第5期102-111,共10页
Marine Geology & Quaternary Geology
基金
国家重点基础研究发展计划"典型弧后盆地热液活动及其成矿机理"(2013CB429700)
国家自然科学基金项目"海底热液活动研究"(41325021)
"台湾东北部龟山岛安山岩的成因研究"(41306053)
"龟山岛热液流体扩散及其对元素分布的影响"(41476044)
"俯冲作用对岩浆活动的影响机制研究:以东马努斯海盆为例"(41706052)
中国科学院战略性先导科技专项"热液系统的物质能量输运及其动力学解析"(XDA11030302)
全球变化与海气相互作用专项"西太平洋俯冲带及弧后盆地体系"(GASI-GEOGE-02)
泰山学者工程专项(ts201511061)
青岛海洋科学与技术国家实验室"鳌山人才"计划项目(2015ASTP-0S17)
关键词
浮岩
气孔充填沉积物
热液活动
矿物组成
微量元素
pumice
sediment fillings in vesicles
hydrothermal activity
mineral composition
trace elements
