Brittle tectonics and major dextral strike-slip zone in the Buda karst (Budapest,Hungary)

Abstract

Three large (kilometric-scale) caves were studied in the Buda hills and the main directions of cave corridors, fault planes and mineralized veins were measured. Different stages of mineralizations are recognised: calcite scaleno- hedrons, baryte, silica, gypsum. New investigations of fluid inclusions in the baryte suggest a crystallization temperature of 50 °C and a freshwater fluid source. Microtectonic analysis allows the reconstruction of the successive tectonic events: (1) a NE-SW extensional phase at the Late Eocene-Early Oligocene limit (phase I), (2) a strike-slip phase with NW-SE compression and NE-SW extension during the Late Oligocene-Early Miocene (phase II), (3) a NW-SE transten- sional phase (phase III) and finally (4) a NE-SW extensional phase of Quaternary age (phase IV). The major phase is the strike-slip one, characterized by an important dextral strike- slip zone: the Ferenc-hegy zone. © Elsevier, Paris     

Fractal dimensions and geometries of caves

Lengths of all caves in a region have been observed previously to be distributed hyperbolically, like self-similar geomorphic phenomena identified by Mandelbrot as exhibiting fractal geometry. Proper cave lengths exhibit a fractal dimension of about 1.4. These concepts are extended to other self-similar geometric properties of caves with the following consequences.Lengths of a cave is defined as the sum of sizes of passage-filling, linked modular elements larger than the cave-defining modulus. If total length of all caves in a region is a self-similar fractal, it has a fractal dimension between 2 and 3; and the total number of linked modular elements in a region is a self-similar fractal of the same dimension. Cave volume in any modular element size range may be calculated from the distribution.The expected conditional distribution of modular element sizes in a cave, given length and modulus, also is distributed hyperbolically. Data from Little Brush Creek Cave (Utah) agree and yield a fractal dimension of about 2.8 (like the Menger Sponge). The expected number of modular elements in a cave equals approximately the 0.9 power of length of the cave divided by modulus. This result yields an intriguing parlor trick. An algorithm for estimating modular element sizes from survey data provides a means for further analysis of cave surveys.     

高密度电阻率法在阿联酋某城C9～C11测区溶洞勘察中的应用

阿拉伯联合酋长国卡里法市B城是一座新规划城市，位于中东海湾沙漠海滩区，由于经三系，第四系地导台含有大量的石膏等萨布哈（Subkha)蒸发盐岩类，大范围发育有大量地下溶洞，其埋藏深度一般为5 m-15m，严重影响了城市建设及工业区开发，在该区采用了高密度电阻率法，克服了地表接地电阻大和溶洞与围岩电性差异小的困难，查明了地下20m深度范围内地下溶洞分布情况，经阿方技术专家验证评价，该次勘查成果可靠，达到了预期目的。     

晋西黄土洞穴成因研究

在野外调查、室内实验基础上,对晋西黄土洞穴的成因进行了分析,研究表明:晋西黄土洞穴的形成是多种内外因素综合作用的结果,主要因素包括黄土的土性、微观结构、节理裂隙、地层结构厚度、水文气候、地形地貌等,其中黄土土性和微观结构是黄土洞穴形成的内因,节理裂隙和地层分布状况为洞穴发育提供了空间和物质基础,水成为黄土洞穴形成的源动力,地形地貌则控制着黄土洞穴的分布。     

西南某水利枢纽废旧煤洞的工程效应研究

通过对西南某水利枢纽工程坝区煤系地层的系统研究,揭示了在坝区左右岸煤洞的展布特征,结合工程,分析了煤洞的存在及其变形的工程效应。最后,对煤洞的变形提出了针对性的处理建议。     

井间地震层析成像技术在岩溶勘察中的应用

介绍了井间地震层析成像技术测试的工作原理及工作方法,然后利用层析成像反演算法对现场获取的原始测试数据进行了解译,得到溶洞沿不同测线的剖面分布图和不同高程处的平面分布图,并将其与场地现有钻孔地质资料进行对比验证,结果表明井间地震层析成像技术有较高的精度和可信度,可得到场地中溶洞的空间分布,从而为工程设计提供可靠的地质资料。     

Simulation of the development of gypsum maze caves

The development of gypsum maze caves under artesian conditions has been simulated. The numerical model simulations show that the evolution of maze caves in this type of setting requires structural preferences such as laterally extended fissure networks in a horizon of the gypsum layer. Without any structural preferences vertical shafts rather than maze caves are predicted to develop. The most important stage for the development of horizontal caves under artesian conditions is found to be the initial karstification period. During this period the structure of the mature conduit system is established. The solutional enlargement of conduits is spatially extended, total dissolution rates are higher than the later ones.     

云南北衙表生金矿形成与保存探讨

通过对云南北衙地区表生金矿形成的地质背景、矿床特征等的研究,重点探讨了其特殊的形成与保存条件。认为北衙地区的表生金矿是“古砂矿”,它的巨大蕴藏量主要得益于其特殊的形成与保存条件：丰富的原生金矿为其提供充足的成矿物质,特别发育的古喀斯特洞穴为“古砂矿”提供了特殊的储存空间,强烈的气液爆破作用形成的热水角砾盖层为其提供了良好的保存条件。     

陆地声纳法在探测岩溶区高铁隧道基底隐患中的应用

沪昆高铁的麻拉寨隧道和贵广高铁的高天隧道在联调联试阶段均发生不均匀沉降和底鼓现象,为了摸清隧道基底致灾原因并对注浆质量进行检测研究,采用陆地声纳法在隧道岩溶段进行了检测,在基底下方探测出较多中、小溶洞,多组中、小断层延伸到基底下方使溶洞之间互相连通,由于雨季隧道周边水压力强烈的变化,造成了隧道不均匀沉降与底鼓,根据数据图像的特殊反应确定了破碎区域和浆注入区,依据探测结果确定治理方案并在治理施工中得到验证。      

喀斯特洞穴康养适宜性评价——以贵州红果树景区天缘洞为例

被誉为“空气维生素”的空气负离子具有调节神经中枢、促进新陈代谢等生物效应,有益于人体身心健康;同时负离子还具有抑菌、杀菌的作用,在喀斯特洞穴中负离子含量高,也造就了洞内洁净的空气。喀斯特洞穴康养就是依托于洞穴环境与小气候而开展的疗养、康体、休闲等一系列有益身心健康的活动。本文采用指数分析法,从人体感受与环境卫生学角度选取人体气候舒适度指数、空气清洁度指数和空气负离子富含度指数构建喀斯特洞穴康养功能指数（CRFI）并以贵州红果树景区天缘洞为实例,来评价喀斯特洞穴的康养适宜性。通过层次分析法确定三个指标权重分别为0.142、0.286、0.572。根据2017年8月至2018年7月的洞穴环境连续监测数据发现,天缘洞洞内氡浓度年均为610.26 Bq.m-3,洞内CO2浓度年均521.900 ×10-6,符合国际辐射安全要求,满足洞穴康养开展的前提条件;洞内年均温为14 ℃,相对湿度大,人体气候舒适度相对较低;洞内正负离子含量在时间与空间上都存在较大幅度的变化,负离子浓度空间分布规律存在以TY-4地下湖为中心向洞口方向逐渐递减趋势,天缘洞4-9月全洞段空气负离子含量较高,空气清洁度指数均高于1.00,属于最清洁空气,极有利于人体健康。天缘洞全年的洞穴康养功能指数显示天缘洞最佳洞穴康养时间为5月与9月,最佳康养地点位于TY-4地下湖附近,仅有12月与1月不适宜开展洞穴康养活动。