热水沉积作用的研究历史、现状及展望

热水沉积作用的研究已经历70余年,目前初步统一了热水沉积及其沉积岩的相关概念。按照形成矿物的温度和颜色特征及类型,将热水沉积作用分为白烟囱型和黑烟囱型,前者主要是在较低温度(100~320℃)下形成硅酸盐、硫酸盐等浅色矿物,后者主要在较高温度(320~400℃)下形成硫化物、氧化物等暗色矿物。大陆的热水沉积热液与海洋热液在温度与物理化学性质方面存在明显差异,大陆热水温度比海洋低,变化范围较海洋大;p H均值比海洋高,变化范围较海洋热水小;Na+K离子浓度与海洋接近,Ca离子与Cl离子浓度比海洋高,但它们的变化范围较海洋大。初步建立了一些关于热水沉积的沉积模式,如海底热液对流模式、盆地压实卤水对流模式、洋中脊岩浆热液—海水混合循环对流模式、热液溢流—喷流—溢流模式。由于热水沉积作用及热水沉积岩的分布具有特殊性和局限性,目前的研究程度较低,对热水沉积的化学过程和热力学过程、热流体成因、物质来源、热水沉积分异、热水沉积机理还不十分清楚,有待于进一步深入系统研究。

A review about research history,situation and prospects of hydrothermal sedimentation

Hydrothermal sedimentation has been studied for over 70 years since being discovered,and its related terminology has been preliminarily unified. It has been classified into the white smoker and the black smoker according to the mineral forming temperature and color,as well as some depositional models. The former deposits light-colored minerals such as silicates and sulfates under lower temperatures(100-320℃),while the latter deposits dark-colored minerals such as sulfides and oxides under relatively higher temperatures(320-400℃). There are some differences in temperature and physics-chemistry between terrestrial and marine hot fluids. The terrestrial thermal fluids are with lower and more various temperatures,higher and relatively fixed pH values,similar Na+K ionic concentrations,and higher and more various Ca and Cl ionic concentrations as to the marine thermal fluids. Some hydrothermal sedimentation models have been set up,such as seafloor thermal fluids convection,compaction brine convection,mixed magma thermal fluid from mid-oceanic ridge-sea water convection,and overflowing-spraying-overflowing. However,due to the specificity and limitation of the hydrothermal sedimentation and its product distribution,the research is not enough. The discussion about the chemical and thermodynamics process of hydrothermal sedimentation is deficient. The origin,source,differentiation of thermal fluids,and the depositional mechanism are not very clear. All of these above should be further studied.