摘要
现代海底热水成矿作用研究的重大进展表现在两个方面：（１）大批活动的和窒息的热液活动区和硫化物矿床在洋脊、岛弧、弧后盆地及板内火山活动中心等海底环境相继发现。在沉积物饥饿洋脊，矿床规模较小，Ｃｕ－Ｚｎ为主，沉积物覆盖洋脊，矿床规模巨大，Ｐｂ－Ｚｎ为主。弧后扩张或弧间裂陷盆地，形成Ｐｂ－Ｚｎ→Ｚｎ－Ｐｂ－Ｃｕ→Ｃｕ－Ｚｎ矿床谱系。岛弧环境硫化物矿床不具规模，板内火山活动中心以氧化物－硫化物矿化为特色。（２）现代海底热水成矿作用观察和研究为古代ＶＭＳ矿床成因研究提供了重要信息，对现有成矿理论产生重要影响。现代成矿观念强调：①海底成矿作用虽可产生于不同环境，但均与张裂断陷事件密切相关。矿床规模和分布特点受张裂速率制约；②成矿物质主体来源于热水循环的火山－沉积岩和下伏基底物质；③硫化物堆积发生于丘堤－烟囱联合构成的机构和结壳下部，通过开放空间的硫化物充填和先成矿石淋滤迁移来实现。④热液流体呈双扩散对流循环。现代海底热水成矿作用的未来研究方向可概括为强度方向和广度方向。广度研究将加大力度去发现新的矿床，强度研究将采用地球物理方法并配以必要的钻探，深入揭示矿床的三维结构和热液体系及成矿机制。
Modern sea floor hydrothermal mineralization is an important and new frontier in modern geosciences. This paper reviews the history, current situation and future of the studies on modern seafloor hydrothermal mineralization. There are two important advances in this field. One is the continual discovery of seafloor active and dead hydrothermal fields and massive sulfide deposits in different seafloor settings, such as mid oceanic ridges, island arc, back arc spreading center and within plate volcanism center etc.. In mid oceanic ridges free from sediments, sulfide ore deposits are small and rich in Cu Zn, whereas along mid oceanic ridges covered by sediments, sulfide deposits are large and rich in Pb Zn. In the back arc basin and/or intra arc rifts, a complete spectrum from Pb Zn and Zn Pb Cu to Cu Zn ore deposits is developed in the trough and depression. Although the hydrothermal mineralization occurs in the island arc and within plate environments, sulfide deposits with industrial significance have not yet been found. Another advance is that the observation and investigation of seafloor hydrothermal processes and mineralization provide invaluable information for understanding the origin of ancient VMS deposits. The new concepts on metallogeny emphasize:(1)The seafloor hydrothermal mineralization processes are related to rifting and subsidence events.(2)Ore forming metals come from host volcano sedimentary rocks and underlying basement through which hydrothermal fluid circulated.(3)Sulfide accumulation occurs under a solid crust consisting of chimney fragments and sulfide mounds, by filling of sulfides into openning space and replacing of high temperature fluid into low temperature sulfide minerals.(4)The hydrothermal fluid constitutes a double diffusive convection system. Future investigation will be extensive and intensive. Extensive investigation will determine the distribution of hydrothermal mineralization in different environments. Intensive investigation will probe more deeply into the deposits and into the hydrothermal systems rooted in crust and upper mantle using geophysical methods as well as drilling.
出处
《地学前缘》
EI
CAS
CSCD
1996年第4期263-273,共11页
Earth Science Frontiers
关键词
海底
热液
成矿作用
发展方向
modern seafloor, hydrothermal process and mineralization, black and white chimneys
