榆神府矿区综合地质环境现状与预测     

夏斐 《煤田地质与勘探》2000,28(3):46-49

榆神府矿区由于特定的自然地理及地质背景,生态环境、地质环境十分脆弱,加之采矿工程引起地下水位下降,新增土地沙漠化和新增水土流失等环境地质问题。本次研究利用先进的神经网络模型对矿区综合地质环境现状进行了评价,并对在采煤条件下的发展趋势进行了预测,神府矿区地质环境质量现状以差为主,榆神矿区以中等为主,采煤后总体上矿区的地质环境质量有所下降。   相似文献   

广丰县天桂岩石灰岩溶洞特征及旅游开发远景     

廖洪鑫 《江西地质》2000,14(2):123-126

本文在阐述天桂岩石灰岩溶洞规模,形态特征的基础上,对洞穴旅游开发远景作了初步评价,并提出开发建议,认为实行综合性的立体开发,能够提高其旅游价值。  相似文献   

浙江瑶琳洞风化碳酸钙景观复生试验   总被引：15，自引：0，他引：15  

宋林华  杨京蓉  林钧枢  王来洪  俞锦标  张汝凡  谭明 《地理研究》1999,18(2):199-206

目前,世界上80%以上的风景旅游洞穴,开放后,大量游客涌入和高能景观灯的应用,洞穴环境及能量埸和化学埸发生了巨大变化,洞穴碳酸钙景观遭受严重破坏,其景观的美学价值大大降低。文中论述了在已遭风化破坏的碳酸钙景观上滴喷高Ca⁺²碱液,吸收洞穴空气CO₂,形成CaCO₃沉积层的试验。试验结果表明,Ca⁺²碱液滴喷技术可以恢复风化碳酸钙景观的美学度,同时又降低洞穴空气中的浓度,改善洞穴环境。  相似文献   

Reconstructing fluvial incision rates based on palaeo-water tables in chalk karst networks along the Seine valley (Normandy,France)     

Carole Nehme  Andrew Farrant  Daniel Ballesteros  Dominique Todisco  Joel Rodet  Diana Sahy  J. Michael Grappone  Jean-Claude Staigre  Damase Mouralis 《地球表面变化过程与地形》2020,45(8):1860-1876

Quantifying rates of river incision and continental uplift over Quaternary timescales offer the potential for modelling landscape change due to tectonic and climatic forcing. In many areas, river terraces form datable archives that help constrain the timing and rate of valley incision. However, old river terraces, with high-level deposits, are prone to weathering and often lack datable material. Where valleys are incised through karst areas, caves and sediments can be used to reconstruct the landscape evolution because they can record the elevation of palaeo-water tables and contain preserved datable material. In Normandy (N. France), the Seine River is entrenched into an extensive karstic chalk plateau. Previous estimates of valley incision were hampered by the lack of preserved datable fluvial terraces. A stack of abandoned phreatic cave passages preserved in the sides of the Seine valley can be used to reconstruct the landscape evolution of the region. Combining geomorphological observations, palaeomagnetic and U/Th dating of speleothem and sediments in eight caves along the Lower Seine valley, we have constructed a new age model for cave development and valley incision. Six identified cave levels up to ∼100 m a.s.l. were formed during the last ~1 Ma, coeval with the incision of the Seine River. Passage morphologies indicate that the caves formed in a shallow phreatic/epiphreatic setting, modified by sediment influxes. The valley's maximum age is constrained by the occurrence of late Pliocene marine sand. Palaeomagnetic dating of cave infills indicates that the highest-level caves were being infilled prior to 1.1 Ma. The evidence from the studied caves, complemented by fluvial terrace sequences, indicates that rapid river incision occurred during marine isotope stage (MIS) 28 to 20 (0.8–1 Ma), with maximal rates of ~0.30 m ka⁻¹, dropping to ~0.08 m ka⁻¹ between MIS 20–11 (0.8–0.4 Ma) and 0.05 m ka⁻¹ from MIS 5 to the present time. © 2020 John Wiley & Sons, Ltd.  相似文献   

Kinetic processes and stable isotopes in cave dripwaters as indicators of winter severity          下载免费PDF全文

Vasile Ersek  Bogdan P. Onac  Aurel Perșoiu 《水文研究》2018,32(18):2856-2862

We examine how the stable isotope composition of meteoric water is transmitted through soil and epikarst to dripwaters in a cave in western Romania. δ²H and δ¹⁸O in precipitation at this site are influenced by temperature and moisture sources (Atlantic and Mediterranean), with lower δ¹⁸O in winter and higher in summer. The stable isotope composition of cave dripwaters mimics this seasonal pattern of low and high δ¹⁸O, but the onset and end of freezing conditions in the winter season are marked by sharp transitions in the isotopic signature of cave dripwaters of approximately 1 ‰. We interpret these shifts as the result of kinetic isotopic fractionation during the transition phase from water to ice at the onset of freezing conditions and the input of meltwater to the cave at the beginning of the spring season. This process is captured in dripwaters and therefore speleothems from Ur?ilor Cave, which grew under such dripping points, may have the potential to record past changes in the severity of winters. Similar isotopic changes in dripwaters driven by freeze–thaw processes can affect other caves in areas with winter snow cover, and cave monitoring during such changes is essential in linking the isotopic variability in dripwaters and speleothems to surface climate.  相似文献   

Late quaternary speleogenesis and landscape evolution in the northern Apennine evaporite areas          下载免费PDF全文

Andrea Columbu  Veronica Chiarini  Jo De Waele  Russell Drysdale  Jon Woodhead  John Hellstrom  Paolo Forti 《地球表面变化过程与地形》2017,42(10):1447-1459

Gypsum beds host the majority of the caves in the north‐eastern flank of the Apennines, in the Emilia Romagna region (Italy). More than six hundred of these caves have been surveyed, including the longest known epigenic gypsum cave systems in the world (Spipola‐Acquafredda, ~11 km). Although this area has been intensively studied from a geological point of view, the age of the caves has never been investigated in detail. The rapid dissolution of gypsum and uplift history of the area have led to the long‐held view that speleogenesis commenced only during the last 130 000 years. Epigenic caves only form when the surface drainage system efficiently conveys water into the underground. In the study area, this was achieved after the dismantling of most of the impervious sediments covering the gypsum and the development of protovalleys and sinkholes. The time necessary for these processes can by constrained by understanding when caves were first formed. The minimum age of karst voids can be indirectly estimated by dating the infilling sediments. U–Th dating of carbonate speleothems growing in gypsum caves has been applied to 20 samples from 14 different caves from the Spipola‐Acquafredda, Monte Tondo‐Re Tiberio, Stella‐Rio Basino, Monte Mauro, and Castelnuovo systems. The results show that: (i) caves have been forming since at least ~600 kyr ago; (ii) the peak of speleogenesis was reached during relatively cold climate stages, when rivers formed terraces at the surface and aggradation caused paragenesis in the stable cave levels; (iii) ~200 000 years were necessary for the dismantling of most of the sediments covering the karstifiable gypsum and the development of a surface mature drainage network. Besides providing a significant contribution to the understanding of evaporite karst evolution in the Apennines, this study refines our knowledge on the timescale of geomorphological processes in a region affected by rapid uplifting. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

东营凹陷南斜坡沙四段沉积环境的地球化学特征   总被引：23，自引：0，他引：23  

宋明水 《矿物岩石》2005,25(1):67-73

东营凹陷是一个北断南超的不对称箕状断陷湖盆,湖盆中的常量元素和微量元素含量及有关元素比值呈现出明显的旋回变化特征。而其中元素的分配及比值的变化、组合都在一定程度上指示着古沉积环境的演化历程。通过分析Fe,Mn,Ca,Sr等元素含量和Fe／Mn,Sr／Ba,Sr／Ca,Mg／Ca等元素比值以及碳氧同位素的变化特征。对东营凹陷南斜坡沙四段沉积时期的沉积环境进行了系统的研究。结果反映了沙四段沉积时期的古气候、古盐度、古湖水面和古生产力基本上都显示出了旋回变化的特征。  相似文献   

三维激光扫描技术在溶洞探测中的应用     

刘兴权  阎曼  杨厚波 《测绘工程》2010,19(5):41-43

由于溶洞的特殊性,传统测量仪器已经不能满足当前对溶洞探测的要求。三维激光扫描技术采用非接触式高速激光测量方式,能在复杂的现场和空间对被测物体进行快速扫描测量,从而获得点云数据。文中介绍激光扫描的工作原理及三维激光扫描的工作流程,并给出采用Riegl LMS_Z420i三维激光扫描仪对吉首至茶洞高速公路吉首岸索塔基坑下的溶洞进行探测的实例。  相似文献   

河北阜平神仙洞探测研究及开发建议     

周文龙  高占冬  吴克华  黎有为  李坡  贺卫 《中国岩溶》2020,39(1):110-118

2015年在太行山区阜平1∶5万水文地质调查工作中发现了北方大型岩溶洞穴--神仙洞。2017年继续对该洞穴采用无纸化测量、三维激光扫描等方式进行重点探测,并比对两套数据以验证无纸化洞穴测量的精度与准确性。通过对神仙洞地下河开展的示踪试验,首次证实了神仙洞与金龙洞相连通;通过对神仙洞发育演化分析以及资源景观评价,认为神仙洞地质遗迹景观,特别是一些组合形态,在北方溶洞中具有较高价值,并提出保护性开发建议,旨在为集中连片特困区旅游扶贫开发提供精准支撑。  相似文献   

Freshwater tufa stromatolites in the basal Purbeck Formation (Upper Jurassic), Isle of Portland,Dorset     

Christopher T. Perry 《Geological Journal》1994,29(2):119-135

Recent interpretations of the tufaceous limestones from within the ‘Caps Beds’ on the Isle of Portland have suggested a depositional environment of intertidal flats and lagoons with typically higher than normal marine salinity levels, a stark contrast with earlier ideas of a freshwater origin. However, evidence is presented in this paper to show that these deposits are indeed most likely to be freshwater in origin. The micro-fabrics observed are typical of those seen in freshwater tufas forming at the present day, and contrast with those observed within intertidal/subtidal stromatolites. Furthermore, the Portland deposits lack syndepositional evaporite deposits, they lack recognizable intertidal deposits, and any lagoonal sediments observed are depositionally distinct from the tufas. Finally, the soil horizons observed are clear evidence of periodic subaerial exposure and isolation from marine influences. Four facies types are identified on Portland: (1) tufaceous limestone; (2) littoral grainstones; (3) subaerial stromatolites; and (4) paleosols. Each facies is repeated a number of times through the sequence, and evidence is presented to show that these formed in a marginal marine setting as a response to a series of minor transgressive (soils to freshwater lakes/lagoon to saline marine/lagoonal) and regressive events (saline marine/lagoonal to soils). The tufa stromatolite deposits themselves, which are often developed around cylindrical holes (representing former tree trunks and branches), are shown to have developed seasonally, by the precipitation of carbonate, due to microbial activity within the freshwater lake environment. Precipitation appears to have been most intense around tree bases (and any associated vegetation), where an active biofilm developed on the underlying soil substrate. Two distinct textures are recognized in this material: (1) micro-porous and (2) macro-porous. These developed together in a crudely laminated, semi-concentric pattern around the holes and together may represent a seasons growth of tufa.  相似文献