年轻冰川沉积砾石的晒退特征及其对岩石释光埋藏测年的启示     

李阳  欧先交  温佳洁  杨婉宜  曾兰华  姚盼  赖忠平 《冰川冻土》2022,44(4):1395-1405

不完全晒退/晒退不均现象是冰川沉积物释光测年所面临的巨大挑战,这一问题限制了传统颗粒沉积物释光方法在冰川沉积物测年方面的应用。最新发展的岩石释光埋藏测年技术,可以根据释光-深度曲线判断砾石是否经历过充分曝光,是解决冰川沉积晒退不均问题的有效途径之一。本工作选择青藏高原东部硬普沟现代冰川前沿为研究对象,采集130个年轻冰川沉积砾石样品,包括93个现代样品和37个小冰期样品,其中20个现代样品采自地表。首先,运用表_{~2 mm}/饱和信号法区分不同冰川沉积环境中砾石样品的晒退程度;再基于SAR和SGC法初步估算样品的等效剂量及其高估情况;然后,统计砾石样品的特征（磨圆度、球度、颜色、晶粒大小、晶粒相对大小、砾石大小等）与晒退程度的关系,找寻晒退良好的砾石及其特征。结果表明大部分采样点的砾石样品呈现了被晒退的特征,平均20.6%的埋藏砾石的岩芯晒退良好,剂量高估程度低;不同沉积类型样品的晒退程度不一,侧碛垄顶部砾石样品晒退程度最好,冰水阶地和现代冰河砾石样品次之,现代冰川后退碛垄间洼地的冰水沉积砾石样品晒退程度最差,剂量高估较严重;磨圆度较差、球度较低、浅色的花岗岩砾石晒退程度较好。综上,冰川沉积砾石的晒退程度与沉积环境、沉积过程、搬运距离、砾石特征等相关,在进行岩石释光埋藏测年采样时,应综合考虑上述情况。  相似文献   

激光扫描技术在重庆罗汉寺文物保护工程中的应用     

黄承亮 《测绘与空间地理信息》2015,(12)

介绍了三维激光扫描技术和相关点云处理软件,应用三维激光扫描技术对重庆罗汉寺文物保护工程进行了数据采集、数据预处理、建筑特征提取、点云建模和三维仿真系统建立,该项目的实施对三维激光扫描技术在文物保护方面的应用具有典型的代表意义和社会经济价值。  相似文献   

湖北大别山(黄冈)国家地质公园地质遗迹资源特征及地学意义     

雷彬  李江风  周学武  赵栋  汪樱 《地球学报》2015,36(3):377-384

湖北大别山(黄冈)国家地质公园是以大陆造山带地质地貌景观和亚热带森林生态景观为主体,集旅游观光、休闲度假、猎奇探险和科学研究、环境保护为一体的大型科学公园。公园所在区域是秦岭造山带的重要组成部分,地质遗迹资源丰富典型,主要分为地质剖面、地质构造、地质地貌、水体景观4个大类,11个类,共100余处地质遗迹景点,其中一部分地质遗迹具有重要的全球典型意义。大别山地质遗迹为探索地球早期演化、开展造山带研究及进行全球对比分析提供了关键证据,在地层学、岩石学、变质地质学、构造地质学、地貌学、水文地质学等各领域具有重要的研究价值。本文研究结果对于系统认识公园地质遗迹状况、建立地质科普示范基地、地质遗迹保护和开发等具有一定参考和借鉴意义。  相似文献   

3维激光扫描技术在岩土文物保护中的应用进展与方向     

吴育华  侯妙乐  张玉敏 《测绘软科学研究》2011,9(2):53-57,73

3维激光扫描是近年来飞速发展的一项高新测绘与信息技术。在文物保护中发挥了重要作用。文章总结了3维激光扫描技术的特点,从岩土文物保护需求出发,以实际文物保护工程为例,重点介绍了3维激光扫描技术在文物信息留存、虚拟修复、监测等方面的应用。最后指出3维扫描技术在岩土文物保护中未来的应用与发展应与文物保护需求紧密结合,而硬软件的改进完善及相关技术的集成应用亦是重要研究方向。  相似文献   

Late Pleistocene-early Holocene paraglacial and fluvial sediment history in the Turbio valley, semiarid Chilean Andes     

Rodrigo Riquelme  Constanza Rojas  Pablo Flores 《Quaternary Research》2011,75(1):166-175

The transitional character of climatic conditions confers great relevance to paleoclimate studies in the semiarid region where glacial and Holocene geomorphologic records are scarce. Here we present the paraglacial and fluvial evolution of the Turbio valley (30°S) using both field observations and ¹⁴C AMS chronology. Two key sites at the uppermost Turbio valley show glacial margins which likely formed during the 17-12 ka Central Andean Pluvial Event and earlier 37-27 ka episodes associated with glacial advances reported elsewhere in the semiarid Andes. Likewise, two episodes of subsequent paraglacial response are identified: a first episode corresponds to early Holocene fine-grained deposits (~ 11,500-7800 cal yr BP) extending far downstream (> 40 km) from the glacial margins. These deposits and coeval debris cones (~ 11,000-5500 cal yr BP) are the result of arid conditions with occasional runoffs that were unable to export sediments along the trunk valley. The second episode corresponds to disconformably overlying fluvial gravels extending ~ 70 km downstream from the glacial margin, indicative of an increase in the fluvial transport capacity occurring not long after 5500 cal yr BP. Fluvial transport increase resulted from a late Holocene shift to wetter climate conditions, representing a forcing factor which enhanced the paraglacial response.  相似文献   

Scale variation of post‐glacial sediment yield in Chilliwack Valley,British Columbia     

Jon F. Tunnicliffe  Michael Church 《地球表面变化过程与地形》2011,36(2):229-243

The Holocene volumetric sediment budget is estimated for coarse textured sediments (sand and gravel) in a large, formerly glaciated valley in southwest British Columbia. Erosion is estimated by compiling volumetric loss estimated in digital elevation models (DEMs) of gullied topography and by applying a non‐linear diffusion model on planar, undissected hillslopes. Estimates of steepland yield are based on estimates of post‐glacial deposition volumes in fans, cones and deltas at the outlets of low‐order tributary catchments. Erosion of post‐glacial fans and tributary valley fills is estimated by reconstructing formerly continuous surfaces. Results are classed by catchment order and compared across scales of contributing area, revealing declining specific sediment yield (in m³ km^?2 a^?1) with catchment area for the smaller tributaries (<10 km²) and increasing specific sediment yield for larger tributaries and Chilliwack Valley itself. Approximately 60% of mobilized sediment is redeposited in first‐ to third‐order catchments, with lesser proportions stored at the outlets of higher order catchments. A simple network routing model emphasizes the significant sediment flux contributions from colluvium, drift blankets and gullies in steeper terrain. As this material is deposited at junctions within the lower drainage network, an increasing proportion of material is derived from remnant valley fills and para‐glacial fans in the major valleys. Yield from lower‐order, steepland catchments tends to remain in storage, indefinitely sequestered on footslopes. These observations have implications for modelling the post‐glacial sediment balance amongst catchments of varying size. After 10⁴ years, the system remains in disequilibrium. The critical linkage lies between low‐order, hillslope catchments (相似文献   

江苏省地质遗迹保护区划研究初探与保护建议   总被引：1，自引：0，他引：1  

方强  徐朱  周晓丹 《安徽地质》2014,(4):280-284

基于地质遗迹资源价值和开发利用条件两方面因素,构建了地质遗迹综合评价体系。遵循地域性、点面结合、保护与开发结合等原则,提出了以地质遗迹分布区划分区为评价单元,综合考虑地质遗迹评价与空间分布特征的地质遗迹保护区划方法。结合保护区划结果,对江苏省地质遗迹保护工作提出了四方面的建议。  相似文献   

地质遗迹旅游资源化：概念、动力及途径          下载免费PDF全文

李如友 《江苏地质》2012,36(1):107-112

地质遗迹是具有独特观赏价值和科普价值的自然遗产,旅游资源化是地质遗迹保护与利用协调发展的最佳方式。提出地质遗迹旅游资源化的概念,分析地质遗迹旅游资源化的动力和途径,认为地质遗迹旅游资源化是旅游需求层次的提高、地质遗迹的保护、地质产业转型、国家政策的支持、地质公园建设的成功5种因素共同作用的结果。地质遗迹向旅游资源的转化需经过地质遗迹调查、地质遗迹评价、旅游产品开发、完善解说系统等步骤。  相似文献   

合肥市大蜀山—紫蓬山地质公园地质遗迹保护研究     

张春雷  查世新  马国明  夏琼 《安徽地质》2012,(1):59-62

合肥市大蜀山—紫蓬山地质公园是一个集多种地质遗迹资源并存的综合性地质公园。园内有代表合肥地区的侏罗纪层型剖面,也有喷发于古近纪的火山遗迹,同时还有大量其他地质构造遗迹。本文在对公园主要保护对象的分析评价基础上,结合目前该园区地质遗迹保护存在主要问题,给出了公园地质遗迹保护的措施,对该地质公园地质遗迹的合理保护起到一定的指导作用。  相似文献   

Why permafrost rocks become unstable: a rock–ice‐mechanical model in time and space     

Michael Krautblatter  Daniel Funk  Friederike K. Günzel 《地球表面变化过程与地形》2013,38(8):876-887

In this paper, we develop a mechanical model that relates the destabilization of thawing permafrost rock slopes to temperature‐related effects on both, rock‐ and ice‐mechanics; and laboratory testing of key assumptions is performed. Degrading permafrost is considered to be an important factor for rock–slope failures in alpine and arctic environments, but the mechanics are poorly understood. The destabilization is commonly attributed to changes in ice‐mechanical properties while bedrock friction and fracture propagation have not been considered yet. However, fracture toughness, compressive and tensile strength decrease by up to 50% and more when intact water‐saturated rock thaws. Based on literature and experiments, we develop a modified Mohr–Coulomb failure criterion for ice‐filled rock fractures that incorporates fracturing of rock bridges, friction of rough fracture surfaces, ductile creep of ice and detachment mechanisms along rock–ice interfaces. Novel laboratory setups were developed to assess the temperature dependency of the friction of ice‐free rock–rock interfaces and the shear detachment of rock–ice interfaces. In degrading permafrost, rock‐mechanical properties may control early stages of destabilization and become more important for higher normal stress, i.e. higher magnitudes of rock–slope failure. Ice‐mechanical properties outbalance the importance of rock‐mechanical components after the deformation accelerates and are more relevant for smaller magnitudes. The model explains why all magnitudes of rock–slope failures can be prepared and triggered by permafrost degradation and is capable of conditioning long para‐glacial response times. Here, we present a synoptic rock‐ and ice‐mechanical model that explains the mechanical destabilization processes operating in warming permafrost rocks. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献