Growth history of hydrothermal chimneys at EPR 9―10°N: A structural and mineralogical study
Based on structural and mineralogical characteristics of four hydrothermal chimney samples collected by submersible Alvin, growth history and formation environment of hydrothermal chimney at EPR 9―10°N are established. It is shown that there occur two types of hydrothermal chimney with different deposition environments at EPR 9―10°N according to differences in their shape, structure and mineral assemblage: type I chimney forms in an environment with high temperature, low pH and strong reducing hydrothermal focus flow and type II chimney forms in a relatively low temperature, high pH and rich Zn hydrothermal environment. Growth of type I chimney begins with the formation of anhydrite. Subsequently deposition of Cu-Fe-Zn sulphide in various directions of chimneys decides the final structure of this type of chimney. According to observation and analysis of mineral assemblages, the formation process of type I chimney could be divided into three stages from early, middle to late. Changes of temperature and major chemical reaction type in the process of hydrothermal chimney formation are also deduced. Different from type I chimney, quenching crystalline of pyrite and/or crystalline of sphalerite provide the growth foundation of type II chimney in the early stage of chimney formation.
作 者： PENG Xiaotong ZHOU Huaiyang 作者单位： Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China 刊 名： 中国科学D辑（英文版） SCI 英文刊名： SCIENCE IN CHINA (EARTH SCIENCES) 年，卷(期)： 2005 48(11) 分类号： P59 关键词： EPR 9―10°N chimney sulfide hydrothermal fluid structure growth history