摘要:
现代洞穴动态监测的一个先决条件就是为洞穴碳酸盐(CaCO3)沉积物—石笋的各种替代指标的解译提供可靠的依据,充分利用现代碳酸盐(CaCO3)沉积物的各种替代指标,并与现代器测气象资料进行相互对比、并用以校正,是精确或定量解释石笋气候替代指标的关键.经对桂林七星岩15号支洞的5个滴水点进行了长达四个水文年(2008~2011年)的大气降水、洞穴滴水、现代碳酸盐沉积物的动态监测和研究,并探讨了洞穴滴水和现代碳酸盐(CaCO3)的δ18O与降水δ18O的相关关系.研究表明,洞穴滴水和现代碳酸盐(CaCO3)的年平均δ18O值非常接近降水的δ18O平均值,并具有与地表降水δ18O相同的变化趋势,反映了洞穴滴水和现代碳酸盐(CaCO3)的δ18O主要来自大气降水的δ18O,即明显受控于降水的δ18O.在4个水文年中,现代洞穴次生化学碳酸盐(CaCO3)沉积物的δ18O值与滴水的δ18O值记录的年内(或年际)变化或多年的变化趋势基本相同,表现出明显的四高峰(δ18O低值区)四低谷(δ18O高值区)的波动变化特征,具有明显的年际、季节性变化规律,显示具有雨热同季的特点.研究结果表明洞穴滴水和洞穴现代碳酸盐(CaCO3)沉积物的δ18O可以记录当地或洞穴上方的气候变化信号,即现代碳酸盐(CaCO3)沉积物的δ18O主要作为夏季风强度或降雨量的替代指标.
Abstract:
A prerequisite for the dynamic monitor of modern cave is to provide a reliable basis for the interpretation of a variety or multiple proxies from modern carbonate (CaCO3) sediment-stalagmites in cave, and to make full use of the multiple proxies from modern carbonate (CaCO3) sediment in field cave monitoring, and compared to local measuring meteorological data each other and correction, is the key of the accurate and quantitative interpreting multiple climate proxies in stalagmites.The four hydrological years of the meteoric precipitation, cave drips, modern carbonate sediments for 5 sites in No.15 branching cave of Seven Star Cave in Guilin during 2008-2011 were continuously monitored, and the correlation between the δ18O of cave drip and modern carbonate (CaCO3) and δ18O of the meteoric precipitation were also discussed. The study results have shown that the annual average δ18O value of cave drip and modern carbonate (CaCO3) is very close to δ18O of the meteoric precipitation and the same change trend, and indicated that the δ18O of cave drip and modern carbonate (CaCO3) came mainly from δ18O of the meteoric precipitation, that is, it is obviously controlled by δ18O of the meteoric precipitation.In four hydrological years, the year (or annual) change and or many years change trends of δ18O record from the modern secondary chemical carbonate sediments (CaCO3) and drop water in cave are basically the same and show obvious change characteristics of four peak (low value area of δ18O) and four trough (high value area of δ18O), and has obvious rule of the seasonal change and year change and has the same seasonal characteristics of the meteoric precipitation or heat. The research results shown that δ18O of drip water and modern carbonate (CaCO3) sediments in cave can record the climate change signal at local or at the top of the cave. So that it has been considered that δ18O of modern carbonate (CaCO3) sediment in cave is mainly taken as the alternative proxies of the summer monsoon intensity and rainfall amount.
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