【作者】 刘珑龙；

【导师】 翟世奎；

【作者基本信息】 中国海洋大学 ， 海洋地质， 2006， 博士

【摘要】 海底热液活动系统是近十几年迅速发展起来的国际研究热点,而大型或集中在一定范围内的众多喷口组成的巨型羽状流系统,由于常常在热液喷溢区上方形成公里量级的热液羽状体并伴随有大型热液沉积多金属硫化物矿体的形成,加之,人们对海底之下的热液作用过程至今仍不清楚,其成因也就成了众所关注而又没有解决的重要科学问题。本文首先对现代海底热液活动的研究现状,包括业已取得的主要研究成果和主要研究方向进行了分析总结。对已有的热液活动的数学模型进行了归纳,分析了其合理性与不足之处。在上述工作基础上,首先建立了模拟普通黑烟囱热液系统及巨羽流形成的基本数学模型,对巨羽流的生成周期、生成时的温度和热液的物质通量进行求解,并探讨了热源温度、渗透率、反应区体积和释放区横截面积等因素对巨羽流生成的影响。得到的主要结论如下:巨羽流系统可以由普通黑烟囱系统发展演化而成,普通黑烟囱流系统经过2到3年的时间则可形成巨羽流系统,巨羽流产生时的热源温度必须超过500℃,喷出热液的最高温度为413℃左右。当反应区热源温度增大时,产生巨羽流的时间明显变小,可以不到一年时间,而巨羽流生成时的温度及巨羽流的最大物质流速几乎不随其变化。随着渗透率的增大,巨羽流的最大物质流速也随之增大,但其增速随渗透率的进一步增大而变缓,并逐渐趋向一个相当于下渗流无摩擦阻力时的极限稳定值。第二个模型是在保持前一个模型基本结构的基础上又考虑了代表下渗低温海水对热液的稀释作用。得到的主要结论有:下渗冷海水是很难进入到烟囱体内对热液进行稀释;当热液高速喷发时,下渗海水通道有可能成为新的热液上升通道,这可能是大面积热液喷溢区存在的主要原因;海底的低温释放流可能是热液系统演化的早期阶段的产物。第四章的模型是模拟巨羽流形成机制的裂缝模型,用来探讨系统中合理的热更多还原

【Abstract】 Seafloor hydrothermal activity system develops up to be an international hot point for study in recent 10 years. The mechanism of formation for megaplume flow system that has a big vent or consists of more vents becomes an important and unsolved subject, because of formation of massive sulphides from its mega hydrothermal plume and the ignorance of formation processes.In the paper, directions and results of the study on modern seafloor hydrothermal activity are analyzed and summarized firstly. Traditional mathematic models are analyzed and their pros and cons are concluded.The basic mathematic model is built to simulate normal black smoker system and the formation of megaplume and to solve the temperature, period and maximal mass fluid rate when megaplume forms. The effects of main parameters like temperature of hot-source, permeability, volume of reaction-zone and area of discharge-zone on the formation of megaplume are discussed. Main conclusions are as follows. A normal black smoker system can evolve into a megaplume eruption. In fact, megaplume hydrothermal eruption will occur in two or three years. The temperature of the hot source must exceed 500℃, while the highest temperature of eruption fluid is about 413℃. If the temperature of the hot source is higher than 500℃, the critical period for megaplume’s formation can be obviously curtailed to be less than 1 year, while the critical temperature and the maximal mass fluid rate are nearly invariable. As the permeability increases, the maximal mass fluid rate increases gradually close to a steady value.The second model adds an embranchment which represents lower-temperature downward permeating seawater to the first model and simulates the dilution effects of permeating cold seawater to hydrothermal fluid. Conclusions are found after analyzing the solutions as follows: Permeating cold seawater can hardly invade the black smoker to dilute the hot fluid. The embranchment zone may become the next bigger discharge-zone when the hot fluid discharges in high speed, which may be更多还原