利用灵山洞钟乳石中流体包裹体研究更新世古环境

Paleoenvironment research of Pleistocene Epoch using fluid inclusions in stalactite of karst cave

流体包裹体在喀斯特溶洞化学沉积物中广泛分布,这些在化学沉积过程中所形成的流体包裹体蕴藏着大量的古环境演化和气候变迁的重要信息。通过采集杭州灵山洞中更新世形成的钟乳石样品,对不同纹圈中流体包裹体进行测定,研究流体包裹体的特征,利用不混溶气-水包裹体中最大密度判别和计算方法确定六个纹圈中精确的形成温度和压力;根据气-水-岩化学反应平衡热力学方法,计算出 CO_2成分浓度和古地下水中 pH 值及钟乳石样品形成过程中的 CaCO_3饱和度等。揭示了杭州地区更新纪古环境演化规律。

Fluid inclusions are widely spread in the chemical sediments of the karst caves. These fluid inclusions formed in the course of chemical sedimentation contain a great deal of important information about paleoenvironment evolution and climatic transition. The stalactite samples of Lingshan karst cave in Hangzhou, formed during the Pleistocene epoch, were collected to determinate the fluid inclusions inside different laminas. The characteristics of the fluid inclusion were studied. The immiscible gas-water fluid inclusions with the maximal density and calculation method were applied to accurately determine the accurate formed temperature and pressure of six stripe layers. According to the equilibrium thermodynamic method of gas-water-rock chemical reaction, the solubility of CO2component concentration, pH value of the paleogroundwater and the saturation degree of CaCO3during the formation of the stalactite samples were calculated. The evolution of the paleoenvironment of the Pleistocene epoch was revealed.