Advances in Earth Science
• Articles •
Liu Changhua,Yiu Xuebo. Introduction to Modern Shallow-submarine Hydrothermal Activity[J]. Advances in Earth Science, 2006, 21(9): 918-924.
The shallow-submarine hydrothermal activities generally appear in the oceanic volcano crowns or flanks. The submerged flanks of island arc volcanoes provide an exceptional opportunity to study the essential differences and similarities between subaerial and submarine venting and the transition from one to the other. Studying the shallow-submarine hydrothermal activities makes us understand comprehensively how the heat of the Earth's interior diffuses slowly. At present the fluid, associated gas and deposits of shallowsubmarine hydrothermal activities are the focuses of current researches. The fluid source is discussed by the fluid's elemental characteristics. The fluid of shallow-submarine hydrothermal activities on the seafloor could be either sea water or meteoric water. The study of shallow-submarine hydrothermal activities associated gases indicates that they are volcanic in origin and strengthen the acidity of hydrothermal fluid. The acidic fluid dissolves elements from the wall rock easily. Therefore, although the distance shallow-submarine hydrothermal fluid traveled is short, the fluid could contain high concentration of dissolved matter. Thus, precipitates may be formed on the seabed surface, even chimney may occur. It suggests that the shallow-submarine hydrothermal activity has a close relationship with volcanic activity. The component of the deposit produced by the shallow-submarine hydrothermal activities is simple. The deposit influences positively the elemental concentration within the ambient waters,e.g. Fe, As, which is a result of the hydrothermal fluid and sea water mixing. Modern shallow-submarine seafloor hydrothermal activity generally occurs near shore, close to the area of human activities. The profundity and span of effect of shallow-submarine seafloor hydrothermal activities on the environment should be a major research focus.