西藏樟木口岸震后滑坡灾害变形InSAR监测分析     

韩冬建  杨成生  董继红 《地质力学学报》2020,26(4):565-574

位于中国和尼泊尔边境的西藏樟木口岸是国家一类陆路通商口岸，也是西藏最大的边贸中心口岸。2015年尼泊尔大地震之后，西藏樟木口岸因多次发生滑坡灾害，而导致口岸关闭。为了调查樟木口岸区域滑坡灾害的分布和变形情况及更好的服务于区域减灾防灾，利用InSAR技术对覆盖该区域的Sentinel-1A和ALOS-2两种卫星影像数据进行了处理，并通过分析视线向年均形变速率图，圈定了17处疑似滑坡，并对其中的5处典型滑坡进行时间序列形变特征分析，监测识别出的滑坡基本沿318国道所在一侧的波曲河左岸分布。InSAR调查结果表明受地震影响樟木地区的滑坡多分布在沿波曲河左岸的陡峭山体上，中尼公路迪斯岗至友谊桥段的古滑坡出现了局部复活的现象，同时樟木镇居民所在的城区也发育有扎美拉山危岩体崩塌滑坡灾害。   相似文献   

Ephemeral rollover points and clinothem evolution in the modern Po Delta based on repeated bathymetric surveys     

Fabio Trincardi  Alessandro Amorosi  Alessandro Bosman  Annamaria Correggiari  Fantina Madricardo  Claudio Pellegrini 《Basin Research》2020,32(2):402-418

Reconstructions of ancient delta systems rely typically on a two-dimensional (2D) view of prograding clinothems but may miss their three-dimensional (3D) stratigraphic complexity which can, instead, be best documented on modern delta systems by integrating high-resolution geophysical data, historical cartography, core data and geomorphological reconstructions offshore. We quantitatively compare three precisely positioned, high-resolution multi-beam bathymetry maps in the delta front and pro delta sectors (0.3 to 10 m water depth) of Po di Pila, the most active of the modern Po Delta five branches. By investigating the detailed morphology of the prograding modern Po Delta, we shed new light on the mechanisms that control the topset to foreset transition in clinothems and show the temporal and spatial complexity of a delta and its pro delta slope, under the impact of oceanographic processes. This study documents the ephemeral nature of the rollover point at the transition between sandy topset (fluvial, delta plain to mouth-bar) and muddy seaward-dipping foreset deposits advancing, in this case, in >20 m of water depth. Three multibeam surveys, acquired between 2013 and 2016, document the complexity in space and time of the topset and foreset regions and their related morphology, a diagnostic feature that could not be appreciated using solely 2D, even very high-resolution, seismic profiles. In addition, the comparison of bathymetric surveys gathered with one-year lapses shows the migration of subaqueous sand dunes on the clinothem topset, the formation of ephemeral cut-and-fill features at the rollover point (few m below mean sea level), the presence of collapse depressions derived by sagging of sediments and fluid expulsion (possibly induced by storm waves) on the foreset, and splays of sand likely reflecting gravity flows on the lower foreset. Though the modern Po Delta is anthropogenic in many respects, its subaqueous clinothem can be studied as a scale model for ancient clinothems that are less resolved geometrically and far less constrained chronologically.  相似文献   

The δ60/58Ni Values of Twenty‐Six Selected Geological Reference Materials     

Weihan Li  Jian‐Ming Zhu  Decan Tan  Guilin Han  Zhouqiao Zhao  Guangliang Wu 《Geostandards and Geoanalytical Research》2020,44(3):523-535

The high‐precision δ^60/58Ni values of twenty‐six geological reference materials, including igneous rocks, sedimentary rocks, stream sediments, soils and plants are reported. The δ^60/58Ni values of all samples were determined by double‐spike MC‐ICP‐MS (Nu Plasma III). Isotope standard solution (NIST SRM 986) and geological reference materials (BHVO‐2, BCR‐2, JP‐1, PCC‐1, etc.) were used to evaluate the measurement bias and intermediate precision over a period of six months. Our results show that the intermediate precision of Ni isotope determination was 0.05‰ (2s, n = 69) for spiked NIST SRM 986 and typically 0.06‰ for actual samples, and the δ^60/58Ni _{NIST SRM 986} values were in excellent agreement with previous studies. Eighteen high‐precision Ni isotope ratios of geological reference materials are first reported here, and their δ^60/58Ni values varied from ?0.27‰ to 0.52‰, with a mean of 0.13 ± 0.34‰ (2s, n = 18). Additionally, SGR‐1b (0.56 ± 0.04‰, 2s), GSS‐1 (?0.27 ± 0.06‰, 2s), GSS‐7 (?0.11 ± 0.01‰, 2s), GSD‐10 (0.46 ± 0.06‰, 2s) and GSB‐12 (0.52 ± 0.06‰, 2s) could potentially serve as candidate reference materials for Ni isotope fractionation and comparison of Ni isotopic compositions among different laboratories.  相似文献   

The role of salinity in fluvio-deltaic morphodynamics: A long-term modelling study     

Zeng Zhou  Luying Chen  Jianfeng Tao  Zheng Gong  Leicheng Guo  Mick van der Wegen  Ian Townend  Changkuan Zhang 《地球表面变化过程与地形》2020,45(3):590-604

Salinity difference between terrestrial river discharge and oceanic tidal water plays a role in modifying the local flow field and, as a consequence, estuarine morphodynamics. Although widely recognized, recent numerical studies exploring the long-term morphological evolution of river-influenced estuaries with two-dimensional, depth-averaged models have mostly neglected salinity. Using a three-dimensional morphodynamic model, we aim to gain more insight into the effect of salinity on the morphodynamics of fluvio-deltaic systems. Model results indicate that the resultant estuarine morphology established after 600 years differs remarkably when a salinity gradient is included. A fan-shaped river-mouth delta exhibits less seaward expansion and is cut through by narrower channels when salinity is included. The inclusion of salinity tends to generate estuarine circulation, which favours landward sediment transport and hence limits the growth of the delta while enhancing the development of intertidal areas. The formation of deltaic channel–shoal patterns resulting from morphodynamic evolution tends to strengthen salinity stratification, which is characterized by an increased gradient Richardson number. The direction of the depth-averaged residual sediment transport over a tide may be opposite to the direction of residual velocity, indicating the significant influence of baroclinic effects on the net sediment transport direction (and hence morphological change). The effect of salinity on morphological evolution becomes less profound when the strength of tidal or fluvial forcing is dominant over the other. The effects of sediment type and flocculation, which are particularly important when salinity gradients are present, are also discussed. Overall, this study highlights that neglecting salinity to simulate long-term estuarine morphodynamics requires more careful justification, particularly when the environment is characterized by fine sediment types (favouring suspended transport), and relatively large river discharge and estuarine depth (favouring baroclinic effects). © 2020 John Wiley & Sons, Ltd.  相似文献   

FY-3D/MERSI-II全球火点监测产品及其应用   总被引：1，自引：0，他引：1  

郑伟  陈洁  闫华  刘诚  唐世浩 《遥感学报》2020,24(5):521-530

FY-3D/MERSI-II全球火点监测产品主要包括全球范围内的火点位置、亚像元火点面积和火点强度等信息,可用于实时监测全球范围的森林草原火灾、秸秆焚烧等生物质燃烧状况。火点判识算法主要根据中红外通道对高温热源的敏感特性,即含有火点的中红外通道像元辐亮度和亮温较远红外通道的辐亮度和亮温偏高,同时较周边非火点的中红外像元偏高,建立合适的阈值可探测含有火点的像元。亚像元火点面积估算主要使用中红外单通道估算,根据亚像元火点面积估算结果对火点强度进行分级,不同的级别表示不同程度的火点辐射强度。基于全球火点自动判识结果,每日生成0.01°分辨率的卫星遥感日全球火点产品,每月生产0.25°×0.25°格点的全球月火点密度图。在利用FY-3D/MERSI-II火点产品开展的全球火点监测应用中,对多起全球重大野火事件进行了监测,为防灾减灾、全球气候变化研究、生态环境保护等方面提供卫星遥感信息支持。  相似文献   

甘肃省地热资源赋存特征及潜力评价     

谢娜  喻生波  丁宏伟  张明泉 《中国地质》2020,47(6):1804-1812

甘肃省地热资源丰富，其地热资源的开发利用具有较大的潜力。本文介绍了甘肃省地热资源分布概况，结合地区构造、地热水化学特征、地热资源量及开发利用现状探讨了甘肃隆起山地对流型与沉积盆地传导型地热资源的赋存特征，并对两种类型地热资源潜力进行了分析评价。结果表明，沉积盆地地热资源分布于河西、陇西及陇东盆地等，热储类型为裂隙型和孔隙型，热储层自元古宙至新生代均有发育，岩性以砂岩为主；隆起山地型地热资源主要分布于祁连山和西秦岭造山带，热储类型为断裂破碎带，岩性以花岗岩为主；通过潜力计算得知，全省热量开采系数≥0.4的仅占29.17%，表明目前甘肃地热资源开采程度较低，开采潜力较大。  相似文献   

福建李坊重晶石矿床中硅质岩硅、氧同位素组成及成因意义          下载免费PDF全文

陈宪  黎敦朋  崔碧云 《地质找矿论丛》2020,35(2):154-160

福建李坊大型重晶石矿床围岩中发育层状硅质岩,为了研究硅质岩的成因,本文对14件硅质岩样品进行了硅、氧同位素分析。结果表明:δ(~(30)Si)分布范围为-0.3×10~(-3)～+0.1×10~(-3),平均值为-0.1×10~(-3);δ(~(18)O)分布范围为10.6×10-3～18.9×10-3,平均值为14.7×10~(-3)。基于该层状硅质岩的δ(~(30)Si)和δ(~(18)O)分布范围特征,结合野外地质调查研究工作的认识,该硅质岩应为原生沉积成因,二氧化硅来源于热水沉积;根据燧石-海水氧同位素地质温度计估算石英的形成温度为100.2℃—198.7℃,平均值为146.0℃,即该硅质岩形成于热水沉积,暗示李坊重晶石矿床形成于热水沉积作用。  相似文献   

敞开酸溶和偏硼酸锂碱熔ICP-MS法测定多金属矿中的稀土元素及铌钽锆铪   总被引：2，自引：2，他引：0  

门倩妮  沈平  甘黎明  冯博鑫 《岩矿测试》2020,39(1):59-67

用电感耦合等离子体质谱法(ICP-MS)测定地质样品中的稀土及难熔元素,混合酸敞开酸溶法和碱熔融法是两种主要的溶样方法。但地质样品组分复杂,元素之间存在相互共生的现象,对于特殊元素、特殊样品用传统酸溶法会造成部分元素消解不完全,使测定结果不准确;而碱熔法的操作过程繁琐,且溶液盐度高,易产生基体干扰和堵塞仪器进样系统。本文改进了传统四酸和五酸体系,采用氢氟酸-硝酸-硫酸敞开酸溶体系,用国家一级标准物质制作标准曲线测定15种稀土元素,方法准确度(ΔlgC)为0.001～0.027。同时改进了偏硼酸锂碱熔法,样品用偏硼酸锂碱熔提取,加入氢氧化钠调节溶液至碱性条件,所测元素与偏硼酸锂共沉淀后过滤分离熔剂,再用硝酸复溶测定15种稀土元素及铌钽锆铪。两种溶样方法的测定值与认定值的相对误差为1.09%～9.30%。将混合酸敞开酸溶法测定稀土元素、偏硼酸锂碱熔法测定铌钽锆铪的结果与其他实验室密闭酸溶法相比,两组数据的相对偏差为0.13%～15.32%。本实验表明,混合酸敞开酸溶法适用于测定地质样品中的稀土元素,偏硼酸锂碱熔法不仅适用于测定地质样品中的稀土元素及铌钽锆铪,也适用于测定如古老高压变质岩石及铝含量高的样品中的铌钽锆铪。  相似文献   

基于与Jason-2数据比对的Jason-3卫星高度计全球数据质量评估   总被引：1，自引：1，他引：0  

刘治中  杨俊钢  张杰  崔伟 《海洋学报》2020,42(3):129-139

Jason-3卫星高度计于2016年1月17日成功发射，2016年2月12日进入预定轨道，与Jason-2高度计同轨进入编队飞行阶段，并落后Jason-2高度计约1分20秒，两者相距约560 km。2016年9月1日，Jason-2高度计变换轨道，编队飞行阶段结束，两高度计进入平行轨道，以增加卫星高度计对地观测的空间覆盖。本研究主要开展了Jason-3高度计的数据质量的评估与检验，包括Jason-3高度计数据可用性和有效性的验证，以及Jason-3高度计和校正辐射计各参数的数据质量监测。重点开展了Jason-2与Jason-3高度计各项参数的综合比较，利用Jason-2与Jason-3高度计编队飞行阶段的数据精确评估了两高度计参数的一致性，并从全球数据角度分析了Jason-3高度计获取各参数的能力以及稳定性；通过与Jason-2互交叉点比较分析评估Jason-3高度计海面高度数据质量情况，验证Jason-3高度计数据精度。结果表明，Jason-3高度计的数据质量满足高度计测高的要求，具有与Jason-1、Jason-2、T/P等高度计相同或更高的测高精度以监测全球海平面变化，此外，Jason-3有效波高参数数据质量明显优于Jason-2高度计。  相似文献   

基于YOLOv3深度学习的海雾气象条件下海上船只实时检测     

王飞  刘梦婷  刘雪芹  秦志亮  马本俊  郑毅 《海洋科学》2020,44(8):197-204

海雾气象条件下船只高精度检测识别面临较大困难，传统的目标识别、定位方法效果差强人意。作者围绕海雾气象条件下不同类型船只的实时检测问题，提出一种基于YOLOv3深度学习的实时海上船只检测新思路。首先构建清晰图片和模糊图片（海雾、雨）的判别方法，实现图片清晰度分类处理；其次为提高海雾气象条件下海上船只的实时检测精度，消除海雾遮挡对目标识别的影响，运用暗通道先验去雾方法对含有海雾的图像实行去雾；最后基于YOLOv3深度学习算法对精细处理后的图像进行船只实时检测。实验结果表明该方法能够在海雾气象条件下高效、准确地检测到船只，对海上复杂环境条件下的船只实时检测研究具有一定的理论指导意义。  相似文献