辽河盆地右行走滑构造运动新证据——基于岩样显微扫描电镜实验结果

依据7块岩样显微扫描电镜实验结果,报道辽河盆地早第三系东营期右行走滑构造运动的重要地质证据.认为辽河盆地早第三系东营期发生过右行走滑构造运动,裂谷后的右行走滑构造运动导致早期拉张断层系可以重新运动,并形成新的断层系.研究成果表明,右行走滑构造运动是辽河盆地复杂构造演化史中的主要地质事件之一,有效地控制了盆地中的断裂体系的格局.早第三系东营期右行走滑构造运动,影响和控制了盆地中油气的运移和聚集.     

Measuring the effect of overgrazing in the Sonoran Desert

Long term overgrazing in Mexico has caused a sharp discontinuity in vegetative cover along the international border in the semi-arid Sonoran Desert. The United States side, protected from overgrazing by the Taylor Act since 1934, exhibits longer, more plentiful grasses and less bare soil than adjoining Mexican lands. Satellite- and ground-based datasets were used in a multi-scale examination of the differential radiative and reflective characteristics of the two regimes. The more exposed Mexican landscape dries more rapidly than the United States following summer convective precipitation. After about three days, depletion of soil moisture evokes a period of higher surface and air temperatures in Mexico. Good correspondence was found between remote and in situ measures of surface temperature and biomass.     

武汉市地理国情监测方案部署方法研究

在第一次地理国情普查成果数据的基础上,武汉市开展了地理国情动态监测。本文结合武汉市国情监测项目实施过程,对地理国情监测方案的流程框架进行了阐述,针对重要技术难点进行了探讨,为将来开展常态化地理国情监测提供了技术支撑,以保证其按时、快速、高效地完成。     

江西冷水坑银铅锌矿田闪锌矿铷-锶测年及地质意义

江西冷水坑矿田是武夷山地区重要的银铅锌集中区之一.无论其是世界上少有的斑岩型银铅锌矿床还是火山沉积-热液改造型矿床都独具特色,具有很高的研究价值.冷水坑矿田含矿斑岩的锆石年龄为162～155Ma,可作为花岗斑岩侵入的时间,绢云母Ar-Ar年龄与含矿斑岩活动时间的一致性说明冷水坑早期成矿发生于斑岩成岩过程中.本文首次采用闪锌矿Rb-Sr同位素测年方法获得冷水坑矿田成矿年龄为126.9±7.1 Ma,代表了冷水坑矿田晚期阶段矿化的年龄.冷水坑Ag-Pb-Zn矿田中大型—超大型矿床的形成,不但受中国东部燕山期构造体制转换的制约,而且受长期多阶段矿化的影响.     

THE IMPACT OF TSUNAMI ON THE COASTLINE OF JERVIS BAY,SOUTHEASTERN AUSTRALIA

The Jervis Bay area offers a diversity of landforms that do not fit within contemporary views of coastal evolution. Field evidence indicates that catastrophic tsunami have had a significant impact on the coast and its hinterland both within and outside the embayment. Runup has overtopped cliffs 80 m above sea level and deposited chevron-shaped ridges to elevations of 130 m on the southern headland. Boulders, up to 6 m in diameter, have been deposited in an imbricated fashion against cliffs, on clifftops, and along shoreline ramps. Bed-form features and the size of transported material indicate flow depths up to 10 m and velocities around 8 m s^-1. While significant Pleistocene material has been swept onto the coastline, mainly in the form of barriers, radiocarbon dating indicates that tsunami have occurred repetitively throughout the Holocene. The most recent event occurred just before European settlement over 200 years ago. [Key words: barrier beaches, coastal geomorphology, tsunami, Jervis Bay, Australia.]     

浅海声速剖面自动分类方法研究

海洋中的声速剖面是影响水声设备效能的重要环境因素之一,声速剖面的自动分类和区划对海洋环境的应用意义重大.依据浅海30分方区按月统计声速剖面,通过归一化处理和Akima差值采样,建立了各方区按月归化后声速剖面的分层梯度样本集,并应用多种系统聚类算法分别对分层梯度样本集进行分析;计算各种算法在不同聚类数水平下聚类结果的总的类内离差和,依据总的类内离差和变化曲线拐点对应的聚类数目,结合分类结果确定浅海声速剖面最优聚类数目.对大量历史统计声速剖面数据的分析结果表明,该方法得到的聚类结果与人工经验分类结果吻合较好.     

基于TerraSuite的网络化三维空间信息平台的构建

介绍了基于TerraSuite的三维影像平台,分析了结合TerraSuite与ArcGIS软件实现网络化三维平台的可行性,构建了基于TerraSuite与ArcGIS的网络化三维空间信息平台。     

水声环境仿真及其可视化技术研究

针对水声环境对舰艇声纳探测效能的显著影响以及主要海域海洋环境特点,建立了浅海和深海水声环境仿真模型,实现了对海区水声环境的快速、准确预报。提出了基于3维声场纹理预积分的水声环境体可视化方法,实现了对水下声场的直观表达与多维分析,从而为水声环境的认知、教学训练以及决策支持提供了有效手段。     

Optimization of UAVs-SfM data collection in aeolian landform morphodynamics: a case study from the Gonghe Basin,China

UAVs-SfM (unmanned aerial vehicles-structure-from-motion) systems can generate high-resolution three-dimensional (3D) topographic models of aeolian landforms. To explore the optimization of UAVs-SfM for use in aeolian landform morphodynamics, this study tested flight parameters for two contrasting aeolian landform areas (free dune and blowout) to assess the 3D reconstruction accuracy of the UAV survey compared with field point measurements using differential RTK-GPS (real-time kinematic-global positioning system). The results reveal the optimum UAVs-SfM flight set-up at the free-dune site was: flying height = 74 m, camera tilt angle = −90°, photograph overlap ratio = 85%/70% (heading/sideways). The horizontal/vertical location error was around 0.028–0.055 m and 0.053–0.069 m, respectively, and a point cloud density of 463/m³ was found to generate a clear texture using these flying parameters. For the < 20 m deep blowout the optimum set-up with highest accuracy and the lowest cliff texture distortion was: flying height = 74 m combined camera tilt angle = −90° and −60°, photograph overlap ratio = 85%/70% (heading/sideways), and an evenly distributed GCPs (ground control points) density of 42/km² using these flying parameters. When the depth of the blowouts exceeded 40 m, the optimum flight/survey parameters changed slightly to account for more challenging cliff texture generation: flying height = 80 m (with −90° and −60°combined camera tilt angle), GCPs density = 63/km² to generate horizontal and vertical location error of 0.024 m and 0.050 m, respectively, and point cloud density of 2597.11/m³. The main external factors that affect the successful 3D reconstruction of aeolian landforms using UAVs-SfM are the weather conditions, manipulation errors, and instrument system errors. The UAVs-SfM topographic monitoring results demonstrate that UAVs provide a viable and robust means for aeolian landform morphodynamics monitoring. Importantly, the rapid and high precision 3D reconstruction processes were significantly advanced using the optimal flight parameters reported here. © 2020 John Wiley & Sons, Ltd.