摘要
现代海底热液活动往往与岩浆作用相伴生.传统的热液系统循环模式认为:海水沿裂隙(通道)下渗,被加热并与围岩发生水岩反应,萃取岩石中的金属元素,形成热液流体并上涌喷出海底,沉积生成多金属硫化物矿体.这一模式合理地解释了构成现代海底热液系统的3个基本要素:流体、通道和热源,与我们现今条件下所观察到的许多事实相吻合.然而,基岩渗透率、热液流体性质、热液生态系统和热液产物上的差异表明现代海底热液活动系统可能存在另一种注入式循环模式,即热液流体来自深部岩浆房流体和挥发性组分的直接注入.据此提出现代海底热液活动系统可能存在两种模式:一种是浅层循环模式,即传统的热液循环模式;另一种是岩浆后期热液注入模式(简称"注入模式").在岩浆作用强烈和构造裂隙发育的环境中,两种模式可能同时存在,形成双扩散对流循环模式.双扩散对流循环模式可以很好地解释现代海底热液活动研究中近期所发现的多种现象和事实.对弧后盆地而言,在研究其岩浆作用与热液活动时,还要考虑板块俯冲的构造背景和俯冲组分及陆壳组分加入等因素,同时构建了适用于弧后盆地海底热液活动系统的理论模型.
Modern seafloor hydrothermal activity is generally accompanied by magmatism.Traditional hydrothermal system model hypothesizes that seawater penetrates through the rifts or cracks,then is heated and reacts with the surrounding rocks gradually leaching out metal elements from the rocks and resulting in the formation of metal-rich,acidic and reductive hydrothermal fluid.Subsequently,the heated fluid moves up along a series of fissures and erupts directly out of the ocean floor leading to precipitations of hydrothermal sulfides.This model reasonably accounts for the existence of fluid,channels and heat sources which are the three fundamental elements of modern seafloor hydrothermal system,and is in accord with many phenomena we have observed so far.However,differences in rock permeability,hydrothermal fluid properties,thermal fluid ecosystem and hydrothermal product indicate that there is possibly another injected circulation pattern for modern seafloor hydrothermal systems,which means the hydrothermal fluid is derived from the direct injection of fluid and volatile components from the deep magma chamber.Accordingly,it is inferred that there possibly are two models for modern seafloor hydrothermal sys-tems：one is the shallow circulation mode,namely the traditional mode of hydrothermal circulation;the other is a magmatic hydrothermal injection mode（＂injection model＂）.In the environment of strong magmatism and well-developed fracture,two modes may exist simultaneously,and the double diffusive convection circulation model is proposed.The double diffusive convection circulation model can be used to explain a variety of phenomena and facts recently discovered in the study of modern seafloor hydrothermal system.Moreover,it is pointed out that the tectonic background of the subduction and the mixing of materials from both subduction component and continental crust are also considered in the study of the magmatism and hydrothermal activity in back-arc basin.Meanwhile,a theoretical model has been constructed for the sea-floor hydrothermal system in back-arc basin taking the Okinawa trough as an example.
作者
王淑杰
翟世奎
于增慧
国坤
张侠
Wang Shujie1 , Zhai Shikui2 , Yu Zenghui2, Guo Kun3, Zhang Xia2(1.Center of Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266001, China 2.Key Lab of Submarine Geosciences and Prospecting Techniques, Ministry of Education, College of Marine Geosciences, Ocean University of China, Qingdao 266100, China 3.Key Lab of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, Chin)
出处
《地球科学》
EI
CAS
CSCD
北大核心
2018年第3期835-850,共16页
Earth Science
基金
国家重点基础研究发展计划("973"计划)项目(No.2013CB429702)
关键词
岩浆作用
海底热液活动系统
双扩散对流循环模式
弧后盆地
冲绳海槽
magmatism
seafloor hydrothermal system
double diffusive convection system model
back-arc basin
Okinawa trough.
