Rapid entrenchment of stream profiles in the salt caves of Mount Sedom,Israel

Rock salt is approximately 1000 times more soluble than limestone and thus displays high rates of geomorphic evolution. Cave stream channel profiles and downcutting rates were studied in the Mount Sedom salt diapir, Dead Sea rift valley, Israel. Although the area is very arid (mean annual rainfall ≈ 50 mm), the diapir contains extensive karst systems of Holocene age. In the standard cave profile a vertical shaft at the upstream end diverts water from a surface channel in anhydrite or clastic cap rocks into the subsurface route in the salt. Mass balance calculations in a sample cave passage yielded downcutting rates of 0–2 mm s^?1 during peak flood conditions, or about eight orders of magnitude higher than reported rates in any limestone cave streams. However, in the arid climate of Mount Sedom floods have a low recurrence interval with the consequence that long-term mean downcutting rates are lower: an average rate of 8·8 mm a^?1 was measured for the period 1986–1991 in the same sample passage. Quite independently, long-term mean rates of 6·2mm a^?1 are deduced from ¹⁴C ages of driftwood found in upper levels of 12 cave passages. These are at least three orders of magnitude higher than rates established for limestone caves. Salt cave passages develop in two main stages: (1) an early stage characterized by high downcutting rates into the rock salt bed, and steep passage gradients; (2) a mature stage characterized by lower downcutting rates, with establishment of a subhorizontal stream bed armoured with alluvial detritus. In this mature stage downcutting rates are controlled by the uplift rate of the Mount Sedom diapir and changes of the level of the Dead Sea. Passages may also aggrade. These fast-developing salt stream channels may serve as full-scale models for slower developing systems such as limestone canyons.     

武隆隧道岩溶地质超前预报综合技术

武隆隧道全长9418m,为渝怀铁路第二长大隧道。该隧道的施工地质条件非常复杂,存在浅埋段、断层破碎带、岩溶暗河、非煤系地层瓦斯和岩爆等不良地质现象。其中,岩溶、暗河以及岩溶涌水是本隧道施工的最主要地质问题。根据岩溶垂直分带结果,武隆隧道处于混流带中,特别是多在季节变动带与水平迳流带之间。自隧道开挖揭露以来,多次发生大型、特大型岩溶涌水灾害。作者根据武隆隧道施工的特点,以地质法为基础,以HSP声波反射法为主要手段,结合TSP203系统和钻探等的超前预报综合技术,进行岩溶地质超前预报。实践证明,武隆隧道综合地质预报技术的应用是基本成功的,值得在同类隧道施工地质预报中借鉴。     

表层岩溶带调蓄系数定量计算--以湘西洛塔赵家湾为例

本文以湖南洛塔赵家湾表层岩溶系统为例,综合利用水位、降雨量、蒸发量及泉流量等长观资料,分别对不同降雨特征下的表层岩溶带调蓄系数进行了定量计算,并对影响表层岩溶带调蓄能力的因素进行了分析。计算得到丰水期赵家湾表层岩溶带调蓄系数为0 14～0 2 8,明显小于枯水期调蓄系数0 44 ;但丰水期久旱后表层岩溶带的调蓄能力接近于枯水期;在丰水期,场雨和连续降雨时的调蓄能力比间歇降雨时的小近1倍。实例计算表明:赵家湾表层岩溶带具有一定的调蓄能力,其地下迳流滞后于降雨至少3d ,调蓄系数确实可以用来定量评价表层岩溶带的调蓄能力。     

梵净山区新元古界下部喀斯特不整合的确认及其地质意义

本文描述了梵净山区新元古界下部鸟叶组与甲路组之间的喀斯特不整合的空间分布、地质特征，从而进一步确认了它的存在；指出该不整合是格林威尔碰撞造山之后强烈隆升的产物，代表了Rodinia超大陆在新元古代裂解前地壳经历的隆起并遭受剥蚀侵蚀的历程，从而对研究该时期地层的空间变异、沉积环境，特别是探讨Rodinia超大陆岩相演化都具有重要的科学意义。     

岩溶盆地地下水长观监测研究

通过覆盖型盆地岩溶盆地中取水深井1987年-2005年盆地地下水长观资料统计分析,系统探讨了岩溶地下水的水位、取水量以及抽水产生的塌陷分布规律,提出了合理开发利用地下水资源的具体措施.     

枣庄岩溶塌陷形成条件及主要影响因素

近年来枣庄市岩溶塌陷频繁发生。通过野外地质调查、现场采样和室内试验相结合的综合手段,对该区的岩溶塌陷覆盖层进行系统地取样并进行深入细致的实验及分析,论述了覆盖层特征对该区岩溶塌陷的影响;运用宏观调查、细观测量和微观分析相结合的研究方法详细论述了地质构造对岩溶塌陷的影响;结合历年水文动态资料、地下水开采量等论述了地下水活动对岩溶塌陷影响。综合认为,地层岩性、覆盖层性质、构造因素是枣庄岩溶塌陷频繁发生的内因,而超量开采地下水则是外部诱发因素。     

典型岩溶流域不同地貌类型景观结构分析——以云南小江流域为例

利用2003年小江流域的TM影像，结合实地调查，再根据流域地质分布和地貌发育情况，将流域地貌类型划分为岩溶地貌和非岩溶地貌两个一级类型景观，在此基础上，根据地貌发育程度结合高程情况，将岩溶区又划分为6个岩溶景观，非岩溶地貌分为两个二级类型景观。应用景观生态学原理，并通过Fragstats 3．3软件在流域尺度上计算了一些相关指标。结果表明：岩溶区的景观生态特征总体上体现了其生态环境的特殊性和脆弱性，地表水资源溃乏，土层薄、土壤资源零星分布且易流失，造成未利用地面积大，石漠化现象严重，土地利用程度低的特点。非岩溶区景观生态由于耕地和林地占绝对优势，石漠化面积少，香农多样性指数和均匀度低，景观的异质性较低，结构较为简单。     

Modeling doline populations with logistic growth functions

Initiation and evolution of a large karst depression population consisting of parent and daughter dolines were spatially and temporally modeled using logistic growth functions. Logistic growth models are well suited for analyzing doline population initiation and evolution because they reflect the density‐dependent growth mechanisms present in the evolution of karst depressions. Seven assumptions based upon previous studies were refined into mathematical statements and tested using more than 2000 dolines from a subpopulation of both parent and daughter karst depressions on the Western Highland Rim and Pennyroyal Plain of Tennessee and Kentucky. Logistic growth models quantify the initiation and evolution of doline populations and interface well with recent models describing the evolution of three‐dimensional conduit systems. Logistic growth models should apply to modeling other doline populations in karst terranes with hydraulically efficient, three‐dimensional conduit systems. Copyright © 2006 John Wiley & Sons, Ltd.     

贵州高原喀斯特景观及其旅游形象

本文通过贵州喀斯特旅游景观类型、特点及优势分析，提出高原、峡谷、峰林、峰丛、瀑布、溶洞是贵州最有代表性的喀斯特景观，它们在空间结上层次丰富的组合，即构成贵州高原绚丽多姿的喀斯特旅游形象，从而展示出贵州喀斯特旅游资源开发的巨大潜力和良好前景。