Geochemical anomalies of hydrothermal plume at EPR 13°N  

作　　者：WANG XiaoYuan1,2, ZENG ZhiGang1, LIU ChangHua1,2, YIN XueBo1, YU ShaoXiong1,2, YUAN ChunWei1,2, ZHANG GuoLiang1,2 & WANG XiaoMei1,2 1 Key Laboratory of Marine Geology and Environment, Institute of Oceanology, Chinese Acadamy of Sciences, Qingdao 266071, China 2 Graduate School of the Chinese Acadamy of Sciences, Beijing 100049, China 

出　　处：《Science China Earth Sciences》2007年第9期1433-1440,共8页中国科学（地球科学英文版）

基　　金：Supported in part by the Pilot Project of Knowledge Innovation Project of Chinese Academy of Sciences (Grant No. KZCX3-SW-223);the National Natural Science Foundation of China (Grant No. 40376020)

摘　　要：During the DY105-12, 14cruise (R/V DAYANG YIHAO, November 2003) on East Pacific Rise (EPR) 12-13°N, the submarine hydrothermal activity was investigated and the CTD hydrocast was carried out at EPR12°39''N—12°54''N. From the temperature anomalies and the concentrations of magnesium, chlorine, bromine in seawater samples, we discover that magnesium depletes 9.3%—22.4%, chlorine and bromine enrich 10.3%—28.7% and 10.7%—29.0% respectively relative to normal seawater at the stations which have chemistry anomalies, moreover temperature and chemistry anomalies are at the same layer. The depletion of magnesium in the plume may be caused by a fluid lacking of magnesium which rises after the hydrothermal fluid reaches the equilibrium with ambient seawater, the enrichment of chlorine and bromine might be the result of inputting later brine which is generated by phase separation due to hydrothermal activity. In addition, the Br/CI ratio in the abnormal layers at the survey area is identical to that in seawater, which implies that halite dissolution (or precipitation) occurs neither when the fluid is vented nor when hydrothermal fluid entraining ambient seawater rises to form plume. From the abnormal instance at E55 station, it is very possible that there might exist a new hydrothermal vent site.During the DY105-12, 14cruise (R/V DAYANG YIHAO, November 2003) on East Pacific Rise (EPR) 12- 13°N, the submarine hydrothermal activity was investigated and the CTD hydrocast was carried out at EPR12°39′N-12°54′N. From the temperature anomalies and the concentrations of magnesium, chlorine, bromine in seawater samples, we discover that magnesium depletes 9.3%-22.4%, chlorine and bro- mine enrich 10.3%-28.7% and 10.7%-29.0% respectively relative to normal seawater at the stations which have chemistry anomalies, moreover temperature and chemistry anomalies are at the same layer. The depletion of magnesium in the plume may be caused by a fluid lacking of magnesium which rises after the hydrothermal fluid reaches the equilibrium with ambient seawater, the enrichment of chlorine and bromine might be the result of inputting later brine which is generated by phase separation due to hydrothermal activity. In addition, the Br/Cl ratio in the abnormal layers at the survey area is identical to that in seawater, which implies that halite dissolution (or precipitation) occurs neither when the fluid is vented nor when hydrothermal fluid entraining ambient seawater rises to form plume. From the ab- normal instance at E55 station, it is very possible that there might exist a new hydrothermal vent site.

关 键 词：SUBMARINE HYDROTHERMAL activity  plume  HYDROTHERMAL fluid  EPR 

分 类 号：P314[天文地球—固体地球物理学]