温泉沉积的钙华的形态和微量元素含量变化对环境演变的响应

This proposed project focuses on the typical hot springs and the travertines depositing from the hot springs in Tibet and Yunnan and other places. The theme of the project is on the formation of the hot springs and the deposition of the travertines. Special attention is paid to the key scientific problem of the response of the changes in physical characteristics and chemical comositions of the travertines to the environmental evolution. The changes in morphology of the travertines and the changes in concentrations of trace elements of the travertines are taken as the core contents of this work. Hydrogeological field investigation, measurements and sampling, analyses and detection of samples, theoretical analyses, hydrochemical modeling and comparison are proposed to be carried out comprehensively in this study. Clear recognitions of groundwater circulation of the hot springs depositing travertines and controlling factors of the travertine depostion are obtained and are taken as the basis of this research. The new travertines depositing from the hot springs in the latest decades are considered as the breakthrough direction of this project. The occurrence and changes in physical characteristics and chemical compositions of the laminated travertines are analyzed in detail. Records of physical features and chemical compositions of the laminated travertines of tens of years and tens of thousands of years and the information reflecting the environmental evolution are obtained. The relationship between the changes in the size and morphology of the travertines and in the physical features and chemical compositions of the laminated travertines and the environmental evolution are established. Changes in the contents of Sr and Ba, and Mg and Mn of the laminated travertines and their indication of the environmental evolution are obtained. The research results are helpful in describing the form and law of substance transport in water circulation of a hot spring in a continental environment. The results are also of important scientific significance in enriching the theory of the reconstruction of paleo-environment and the research methods of the global changes in climate.

本项目聚焦西藏、云南等地代表性的温泉及其沉积的钙华，围绕温泉形成和钙华沉积的主题，针对钙华的物理特征和化学成分变化对环境演变的响应的关键科学问题，以钙华形态变化和钙华微层微量元素变化为核心内容，综合运用野外水文地质调查、现场观测和采样、室内分析和测试、理论分析、水化学模拟和对比分析等研究手段和方法，在查明沉积钙华的温泉的水文循环和钙华沉积影响因素的基础上，以近几十年温泉沉积的新钙华为突破方向，深入剖析钙华微层的物理特征和化学成分变化的原因，获得高分辨率的近几十年来和几十万年来的热水钙华微层物理特征和化学成分的记录及其所反映的环境演变的信息，建立热水钙华的沉积规模和形态变化以及热水钙华微层物理特征和化学成分的变化与环境演变的响应关系，揭示钙华微层Sr和Ba、Mg和Mn等的含量变化特征及其环境指示意义，阐明陆地温泉水文循环中物质迁移的方式和规律，丰富古环境重建的理论和全球气候变化的研究方法。

一个温泉地下热水系统构成一个相对独立的陆地水文循环系统，其分布、形成和泉口沉积的钙华是自然界水循环过程中物质迁移和能量传输科学问题的重要组成部分。温泉的出露和沉积的钙华隐含着地下地质、地热学、水动力学和水化学等多方面的丰富信息。本项目主要以云南、四川和西藏等地出露的数十个温泉（咸温泉）为研究对象，运用野外水文地质调查与观测、采样与室内测试、对比分析和综合分析等多种研究方法，获得温泉及钙华野外观测和室内测试的大量数据，分析这些温泉的分布、出露和形成的区域地质背景和水文地质条件、水循环及其演化特点，探讨部分重点的沉积钙华的温泉的水动力因素和水化学因素，从水量和水质两个方面分析温泉的成因和提出成因模式，探讨温泉沉积钙华和不沉积钙华的水化学控制因素，总结钙华的形态特征和微层的微量元素含量变化，提出钙华的形态分类，分析钙华的规模和形态的变化以及钙华微层的化学成分的变化与环境演变的关系。研究成果对于阐明陆地水文循环中物质迁移和转化的方式和特点，揭示温泉钙华沉积的原因及其与环境演变的关系，丰富地下水循环和水-岩作用的理论，具有重要的科学意义，对于温泉的开发利用和钙华遗迹的保护也具有重要的实际意义。