钙华天然海绵地质体多孔特性及其对水循环调节意义——以四川黄龙为例

Porosity of travertine natural sponge geological bodies and its significance in regulating water circulation:A case study of travertine at Huanglong ravine,Sichuan Province,China

四川黄龙自然遗产点以钙华景观闻名海内外,其钙华体多孔性地质结构,使钙华地质体具备"海绵"特性。本文通过电子扫描显微镜(SEM)和探地雷达、电磁法等地质探测技术对钙华地质体的多孔性质和水循环特性进行研究,并结合多年现场踏勘经验探讨了钙华地质体的多孔性质对水循环的调节意义。分析结果显示,黄龙钙华体经过地质作用形成了不同尺度的孔隙结构,其中生物参与形成的微观孔道具备"渗透、净化"功能;侵蚀作用产生的可视孔洞、缝隙快速透水,并进一步发育成塌陷区和钙华漏斗。彩池、溶洞和裂缝为水体储蓄和运移提供很好通道和场所,地质探测分析表明典型钙华段地下腔体具备"蓄水、排水"功能。各尺度孔隙互相影响,共同调节黄龙景区内的地表-地下水循环系统。初步研究发现,藻类在黄龙钙华沉积过程中具有加速和减少孔隙形成的双向调控作用,未来将结合藻类在钙华构筑过程的作用,继续深化黄龙钙华地质体的孔隙结构性质研究,为钙华景观的维护和保育提供参考。

The Huanglong Scenic and Historic Interest Area,a Natural Heritage site in Sichuan,is famous for its travertine landscape.The porous geological structure of travertine makes it possess the similar property with that of'sponge'.In this paper,the porous structure and water circulation property of travertine geological body have been studied by using scanning electron microscopy(SEM),ground penetrating radar,electromagnetic methods,and other geological detection techniques.Meanwhile,the water circulation regulating significance of the porous structure of travertine geological body had been discussed,combining with many years field reconnaissance experience.The analytical results show that the travertine geological body in the Huanglong ravine has various pore structures at different scales due to geologic processes.The microscopic pores formed with the involvement of biological action have functions of'permeability and filtration'.The visible pores and crevices produced by erosion are capable to let water be rapidly permeated.They could further be developed to collapsed areas and travertine funnels.The pools,caves,and cracks provide good channels and locations for the water impoundment and migration.Geological exploration techniques have confirmed that the underground cavities in the typical travertine section have the function of'water storage and drainage'.The pores at different scales interact with each other to jointly regulate the surface-groundwater circulation system in the Huanglong scenic area.This preliminary study has found that algae had the bidirectional controlling actions for accelerating and reducing the formation speed of pores in the Huanglong travertine during the deposition process.In the future,combining with the study on the role of algae for the travertine formation process,we will further undertake the study of pore structure properties of the Huanglong travertine geological body,in order to provide helpful reference for the maintenance and conservation of travertine landscape.