湖泊碳酸盐矿物的形成过程及古气候环境指示意义

Review on Formation of Lacustrine Carbonate Minerals and Their Paleoclimate Significance

湖泊沉积物中的碳酸盐矿物蕴含了区域地质背景、沉积过程、气候环境、湖泊生物活动以及湖水物理化学性质等信息,已成为古气候、古环境重建的重要研究载体之一,为认识区域和全球气候环境变化提供了重要依据。在前人研究的基础上,归纳了控制湖泊碳酸盐形成及其碳、氧同位素组成变化的影响因素,阐明了它们所指示的古气候环境意义,回顾了湖泊碳酸盐在古气候环境重建中的应用现状,指出了其存在问题,展望了该领域的研究方向和趋势,为推动湖泊碳酸盐古气候环境重建提供参考。结果表明:湖泊碳酸盐的形成受温度、降水、生物活动、湖泊水文条件、湖水物理化学性质等的影响,因此,碳酸盐矿物含量变化可以指示湖水温度、有效湿度、入湖水量、生物活动、湖区主导风的强度等;碳酸盐δ^(18)O和δ^(13)C值是古湖泊研究中常用的代用指标,能较好地反映湖水温度、有效湿度、湖泊生产力大小、湖水物理化学性质、与大气环流有关的水汽来源和传输路径的转变以及古洪水事件等重要的古气候环境信息。湖泊碳酸盐的古气候意义愈加丰富,也将继续在未来的古气候研究中发挥巨大作用。

Carbonate minerals in the lacustrine sediments bear abundant geological and environmental information, such as regional geological background, sedimentary process, the changes of climatic and environmental conditions, the activities of aquatic organisms and physical-chemical properties of lake water. Thus, they have become one of the important approaches for paleoclimatic reconstruction. Based on the previous literatures, the factors controlling the formation of lacustrine carbonates and the changes of carbon and oxygen isotopic compositions were summarized, the paleoclimatic significance was interpreted, the application progress of lacustrine carbonates in paleoclimate and paleoenvironment reconstructions was reviewed, and some problems existing in the application of lacustrine carbonate were also pointed out. Furthermore, the development trend in this field for future research was proposed. The results show that the formation of lacustrine carbonates is related to temperature, precipitation, biological activity, lake hydrology and physical-chemical properties of lake water;therefore, the fluctuation of carbonate content can indicate the temperature, effective humidity, water inflow, biological activity and even the intensity of the dominant wind in this region;stable oxygen(δ^(18)O) and carbon(δ^(13)C) isotope compositions of carbonates are common proxies in paleolimnological studies, which can be used for reconstructing various climatic and environmental parameters including temperature, effective humidity, productivity, physical-chemical properties of lake water, the change of water vapor source and transmission path related to the atmospheric circulation and paleoflood events. The paleoclimatic significance of lacustrine carbonate is becoming richer and more complex, and it will continue to play a pivotal role in the future paleoclimate research.