张家界以其独特罕见的石英砂岩峰林地貌闻名于世,一直是地貌学家、地质学家们关注的焦点,但关于其形成年代问题尚显薄弱,一直缺乏系统深入的研究.本文对索溪流域不同层状地貌进行了地貌学、沉积学和年代学综合研究.研究结果表明,索溪河谷普遍发育三级阶地,T;很少发育,主要表现为河流两侧化置较高的古宽谷或剥蚀面.岩溶洞穴黄龙洞从上往下可分为4层,最高层发现的砾石层表明,该砾石为外源砂岩,至少形成于中更新世暖湿环境下.张家界砂岩峰林可明显分为四个主要层次,与索溪中下游的河流阶地、黄龙洞穴在地貌形态上具有良好的对比关系,据此可推断张家界砂岩峰林最早形成于中更新世.这种青年到壮年期地貌,总体上相对稳定.在今后的地质公园建设中,应注意旅游资源的科学合理利用与保护工作,采取科学有序的方式进行开发,并要做好地貌景观资源的科学保护工作.%Zhangjiajie, well-known for its spectacular sandstone landforms, has been the subject of geomorphologists and geologists for decades. Prior to our present study, however, little is known about the timing of these spectacular sandstone landforms. Integrating the geomorphological, sedimentological and geochronological techniques, the correlations between sandstone landforms, fluvial terraces and karst caves have been investigated. Our results indicate that three terrace levels are well developed in the Suoxi River, with terrace level T4 locally emerging in the middle Suoxi catchment. Huanglong Cave, a typical karst cave in the study area, can be divided into four vertical levels, with the gravel layer occurring in the topmost level. Sedimentological analysis indicates an allochthonous source for the gravels, which have been formed under a warm and humid environment in Middle Pleistocene. Four primary geomorphic levels are distinctive in the Zhangjiajie sandstone landforms, displaying a good geomorphic correlation with the alluvial terraces and Huanglong Cave in the middle-lower reaches of the Suoxi River. We thus can infer the timing of sandstone landforms formation in Zhangjiajie at Middle Pleistocene. This landform is in the period from adolescence to maturity, showing relatively stability. In the process of Geopark constructing,tourism resources should be utilized and protected properly, allowing scientific protection and sustainable management.
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