三论洞穴石笋沉积速率--以衙门洞一号石笋为例

On the Growth Rate of Cave Stalagmite for the Third Time——Case Study of No.1 Stalagmite in Yamendong

综合观测我国南方洞穴30多根大石笋纵剖面。其中,精选近20根结构、构造清晰的剖面,进行高精度系统测年及沉积特征的对比研究,认定沉积速率是石笋生长过程时空轨迹的数学描述,记录石笋或石笋段沉积生长过程的时间和物质组分、结构构造及其空间组合。确认石笋沉积(生长)速率是沉积特征的缩影,具有多旋回、多级次特征,可作重建古气候环境的替代指标之一,具有时空双重含意。在石笋沉积速率研究积累和Y 1测年系列数据的基础上,提出沉积速率以10 mm/100 a作为气候冷、暖转变的分界值和冷、暖彼此趋近的临界值,建议以此作为南、北方甚至是地带性气候冷暖转变的分界或趋近的临界值。在重建古气候环境研究实践中,探索、完善、深化石笋沉积特征的综合对比;同时提出影响石笋沉积速率的自然条件是主控因素。其中,气候、地质、环境等是关键。而获得准确沉积速率,采样、测试、研究方法、剖面选择等,人为因素重大作用。在实践方面以结语的3点建议供同行参考。

More than 30 sections of stalagmites were observed,and 20 sections with clear structure were chosen to study high-accuracy dating and deposition characteristic contrast.The growth of stalagmites can be described by its sediment rates.The sediment rates can record the deposition and growth time of stalagmites,its components and structure,and the space of stalagmites combination.So,the sediment rates can be thought as the mathematics description of time and space about growth of stalagmite.The growth rate of stalagmite is the reduction of sediment characters whit polycyclic and multilevel and it is of great importance to the reconstruction of paleo-climate.On the basis of studying the stalagmite sediment rates and Y1 data,we propose that the climate can be divided into cold and warm by the rate of 10mm/100a.The rate also can be used as the critical value of the change of zonal climate.During the process of reconstructing the paleoclimate, we should explore,supplement,and deepen the comparison of sediment character.We also propose that the sediment rates are mainly controlled by natural conditions,including climate,geology,environment,and so on.The human factors is more important when we sampling,testing,selecting the profile,and so on.The conclusions can be used as references to our craft brothers.