贵州思南石林资源特征及成景机制探讨

Characteristics and genetic mechanism of the stone forest in Sinan County,Guizhou Province

贵州思南石林目前正建设成为思南乌江喀斯特国家地质公园长坝石林景区.本文通过石林的形态特征对比研究及区域地质环境的调查,分析了石林的景观资源特征,并探讨了石林的形成条件和发育演化过程,结果表明：（1）思南石林属溶洼边坡型石林,石林形态多样、个体高大且象形景观众多,加之石林生态环境良好,风光秀美,具有较高的观赏、科研和科普及开发价值.（2）思南石林以质纯层厚的下二叠统深色泥晶灰岩为主,并处于南东—北西构造应力带上,利于较高大石林的形成和保存；地貌上,石林发育在喀斯特单面山与溶蚀洼地之间的斜坡上,不同地貌部位的水动力条件导致石林形态和分布的差异；气候上,思南地区自新第三纪以来以热带、亚热带温湿气候为主,为石林的形成提供了充足的外营力条件；此外,来自碎屑岩区的外源水侵蚀和下伏碎屑岩的隔水顶托作用为大面积石林的形成提供了很好的水环境条件.（3）石林形成过程可归纳为海侵沉积、抬升剥蚀、构造变形、土下溶蚀和地表塑造5个阶段；其中地表塑造阶段是石林的成景时期,依据有关侵蚀数据计算得出石林成景时代约为30.04～45.06 ka,即晚更新世中晚期.

The Sinan stone forest is located between the Wuling mountain and the Daloushan mountain range in the northern edge of the transition slope between Guizhou plateau and Xiangxi hills.The Liangshan group,Qixia group and Maokou group of the upper Paleozoic Permian are the major strata in the scenic.There are no strata of the Devonian and the Carboniferous of the lower Palaeozoic.The Sinan scenic is being constructed into the Changba stone forest scenic area of the Wujiang karst national geopark now.By means of comparative study on the morphologic characteristics of different stone forests and survey on region geologic environments and scenic resources,the geologic conditions for the formation and development of the Sinan stone forest are analyzed.The results show that,（1）The Sinan stone forest is depression slope stone forest with various morphs involving sword-shaped,castle-shaped,tower-shaped and cylindrical as well as needle-shaped,and the single stone peak is high up to 20 to 30 m,furthermore the pictographic landscapes are multitudinous,not only very graceful,the formation and evolution also provide a typical case for the research of stone forest and science education.And the ecology is kept very well,the stone forest,trees and farmhouses mix together,having a very high aesthetic value and the value of tourism development; （2）Geologically speaking,the Sinan stone forest are mainly developed in the pure and thick dark-colored micrite of the Permian system and lies on the southeast-northwest tectonic stress zone where cracks and joints networks are good for the formation and preservation of the high stone; geomorphologically,the Sinan stone forests are developed on the slope between the karst cuesta and the uvala,the hydrodynamic conditions at different parts of the landform caused the differences in morphology and distribution of the stone forest; climatically,from the Neogene,the Sinan is mainly the tropical,subtropical humid,the cold and dry climate only briefly interludes in the course,the warm,humid and rainy weather have provided plentiful external agents for the formationof the stone forest; hydrogeologically,the Sinan stone forest is developed in carbonate interbeded with clastic rock strata,the erosion by exogenous water from clastic rocks and the jacking of the underlying clastic rocks provide good water conditions for the formation of the large area of stone forests; in addition,the favorable vegetation also provide large quantities of CO2 and organic acids for the dissolution; （3）Its formation process can be reduced to five stages：the diagenetic stage（P-T2）,the lifting denudation stage（T3-J3）,the tectonic deformation stage（K1Q1）,the soil erosion stage（Q1-Q3） and the surface shaped stage （Q3-Q4）.According to the erosion data it is calculated that the Sinan stone forest is formed around 30.04-45.06kaBP,that is in the middle and late period of the late Pleistocene.