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石笋生长速率通常被作为反映古气候或古环境变化的有效代用指标。本文以湖北三宝洞22万年以来17支石笋为材料,实测了190个~(230)Th年龄,其生长曲线显示MIS 1和MIS 5阶段平均生长速率较大,超过70μm/a;MIS 2,MIS 3,MIS 4和MIS 6阶段生长速率较慢,均低于25μm/a,甚至停止生长。间冰期平均生长速率比冰期增加了1～2倍以上,且具有“爆发式”快速生长的特点。以5000年为步长的同一洞穴17支石笋生长频率支持平均生长速率的研究结果,说明在轨道尺度上较大的石笋生长速率能够有效地指示暖湿的气候条件。研究结果表明,间冰期高海平面和强太阳辐射增强了研究区季风环流,提高了地表植被覆盖率,有利于洞穴岩溶水过饱和,从而导致间冰期多支石笋连续高速生长。
The growth rate of stalagmite is usually used as an effective proxy to reflect the paleoclimate or paleoenvironmental changes. In this paper, 17 stalagmites from 190 to 230 Th ages were collected from a period of 220,000 years in Sanbao Cave, Hubei Province. The growth curves showed that the average growth rate of MIS 1 and MIS 5 was larger than 70μm / a. MIS 2, The growth rates of MIS 3, MIS 4 and MIS 6 were slower than those of 25 μm / a and even stopped. The average growth rate of interglacials increased more than 1 ~ 2 times than that of glaciers, and has the characteristics of “explosive” rapid growth. The results of the study on the average growth rate of 17 stalagmites in the same cave with 5000-year increments suggest that the larger stalagmite growth rate on the orbital scale can effectively indicate the warm-humid climatic conditions. The results show that the inter-glacial high sea level and intense solar radiation enhance the monsoon circulation in the study area, increase the vegetation coverage of the surface vegetation, and promote the supersaturation of the cave karst water, resulting in the continuous high-speed growth of multiple stalagmites during the interglacial period.