长白山天池火山天文峰期黄色浮岩成因研究     

潘波  程滔  徐丹  刘松军 《岩石学报》2020,36(7):2067-2080

长白山天池火口北侧天文峰之上,一套醒目的黄色浮岩引起广泛的关注,其颜色成因问题更是讨论的热点。本文通过野外地质调查、显微形貌和地球化学分析等方法,探索了黄色浮岩的颜色成因问题,并对此次喷发活动(天文峰期喷发)有了更进一步的认识。黄色浮岩与其下部灰白色浮岩应为同一期喷发所形成,两者成分一致且特征相似。黄色浮岩初始颜色为灰白色,后期受所处环境(降水丰富)与本身气孔特征的影响,浮岩内发生了元素析出和元素沉淀的过程。首先,浮岩内Si与H2O结合形成弱硅酸(H2Si O3),而大气中CO2与H2O结合形成弱碳酸(H2CO3),在弱酸环境下火山玻璃逐渐析出Si、K、Al、Ca和Fe等阳离子,而析出的元素易溶于水的部分被流水带走,难溶于水的Fe与Al富集并粘附在火山玻璃壁上,同时由于Fe可与H2O络合形成黄色的Fe的水合物(Fe2O3·n H2O),而Al与H2O络合形成凝胶状白色水合物(Al2O3·n H2O),两者混合形成了黄色胶状物粘附在火山玻璃壁上,改变了浮岩原本的灰白色,形成了黄色浮岩。因此,天文峰期浮岩的黄色是由于后期风化淋滤作用所造成,属于次生色。本研究提高了对火山喷发堆积物风化淋滤作用过程的认识,也为其他地区相似颜色变化问题的讨论提供了借鉴。  相似文献   

Main active faults and seismic activity along the Yangtze River Economic Belt: Based on remote sensing geological survey     

《China Geology》2020,3(2):314-338

The Yangtze River Economic Belt (YREB) spans three terrain steps in China and features diverse topography that is characterized by significant differences in geological structure and present-day crustal deformation. Active faults and seismic activity are important geological factors for the planning and development of the YREB. In this paper, the spatial distribution and activity of 165 active faults that exist along the YREB have been compiled from previous findings, using both remote-sensing data and geological survey results. The crustal stability of seven particularly noteworthy typical active fault zones and their potential effects on the crustal stability of the urban agglomerations are analyzed. The main active fault zones in the western YREB, together with the neighboring regional active faults, make up an arc fault block region comprising primarily of Sichuan-Yunnan and a “Sichuan-Yunnan arc rotational-shear active tectonic system” strong deformation region that features rotation, shear and extensional deformation. The active faults in the central-eastern YREB, with seven NE-NNE and seven NW-NWW active faults (the “7-longitudinal, 7-horizontal” pattern), macroscopically make up a “chessboard tectonic system” medium-weak deformation region in the geomechanical tectonic system. They are also the main geological constraints for the crustal stability of the YREB.  相似文献   

短脉冲激光在实验室天体物理方面的研究进展     

孙嘉宁  袁大伟  王菲鹿 《天文研究与技术》2021,(2):248-254

随着啁啾脉冲放大技术(Chirped Pulse Amplification,CPA)的飞速发展,激光功率密度实现了飞跃式的提升,利用短脉冲激光开展实验室天体物理研究的条件日趋成熟。短脉冲激光与靶相互作用可以产生相对论粒子(正负电子、质子、中子等)和高能电磁辐射(X射线、γ射线),这些粒子和辐射的产生过程与天体中的某些物理现象相对应。介绍了利用短脉冲激光开展实验室天体物理的研究进展,重点介绍了核天体物理、空心离子光谱学、相对论无碰撞冲击波以及等离子体状态诊断等。  相似文献   

Quantifying suitable dynamic water levels in marsh wetlands based on hydrodynamic modelling     

Peng Hu  Zefan Yang  Qiande Zhu  Weize Wang  Qin Yang 《水文研究》2021,35(2):e14054

The water level of marsh wetlands is a dominant force controlling the wetland ecosystem function, especially for aquatic habitat. For different species, water level requirements vary in time and space, and therefore ensuring suitable water levels in different periods is crucial for the maintenance of biodiversity in marsh wetlands. Based on hydrodynamic modelling and habitat suitability assessment, we determined suitable dynamic water levels considering aquatic habitat service at different periods in marsh wetlands. The two-dimensional hydrodynamic model was used to simulate the temporal and spatial variation of water level. The habitat suitability for target species at various water levels was evaluated to obtain the fitting curves between Weighted Usable Area (WUA) and water levels. And then suitable water levels throughout the year were proposed according to the fitting curves. Using the Zhalong Wetland (located in northeastern China) as a case study, we confirmed that the proposed MIKE 21 model can successfully be used to simulate the water level process in the wetland. Suitable water levels were identified as being from 143.9–144.2 m for April to May, 144.1–144.3 m for June to September, and 144.3–144.4 m for October to November (before the freezing season). Furthermore, proposed water diversion schemes have been identified which can effectively sustain the proposed dynamic water levels. This study is expected to provide appropriate guidance for the determination of environmental flows and water management strategies in marsh wetlands.  相似文献   

捷联式航空重力扰动矢量解算及误差补偿     

郭栋  孙中苗  吴富梅  张琪 《大地测量与地球动力学》2018,38(12):1295-1301

介绍捷联式航空重力矢量测量的基本原理，利用波数相关滤波（WCF）、比力线性校正的方法对重力扰动的水平和垂向分量进行误差补偿，评定内符合精度。对国产捷联式航空重力矢量仪的某次试验数据进行处理，以验证和评估航空重力矢量仪的性能。结果表明，在半波长分辨率为7.5 km时，6条重复测线的重力扰动水平分量经波数相关滤波处理后，东、北向分量的平均内符合精度分别从9.77 mGal、9.18 mGal提高到5.95 mGal、3.83 mGal；对比力的垂向分量线性校正后，将解算的重力扰动垂向分量再用WCF方法处理，其平均内符合精度从1.27 mGal提高到0.59 mGal。  相似文献   

Study of the flood control scheduling scheme for the Three Gorges Reservoir in a catastrophic flood          下载免费PDF全文

Shanghong Zhang  Zhu Jing  Wenda Li  Yujun Yi  Yong Zhao 《水文研究》2018,32(11):1625-1634

The Three Gorges Project is the world's largest water conservancy project. According to the design standards for the 1,000‐year flood, flood diversion areas in the Jingjiang reach of the Yangtze River must be utilized to ensure the safety of the Jingjiang area and the city of Wuhan. However, once these areas are used, the economic and life loss in these areas may be very great. Therefore, it is vital to reduce this loss by developing a scheme that reduces the use of the flood diversion areas through flood regulation by the Three Gorges Reservoir (TGR), under the premise of ensuring the safety of the Three Gorges Dam. For a 1,000‐year flood on the basis of a highly destructive flood in 1954, this paper evaluates scheduling schemes in which flood diversion areas are or are not used. The schemes are simulated based on 2.5‐m resolution reservoir topography and an optimized model of dynamic capacity flood regulation. The simulation results show the following. (a) In accord with the normal flood‐control regulation discharge, the maximum water level above the dam should be not more than 175 m, which ensures the safety of the dam and reservoir area. However, it is necessary to utilize the flood diversion areas within the Jingjiang area, and flood discharge can reach 2.81 billion m³. (b) In the case of relying on the TGR to impound floodwaters independently rather than using the flood diversion areas, the maximum water level above the dam reaches 177.35 m, which is less than the flood check level of 180.4 m to ensure the safety of the Three Gorges Dam. The average increase of the TGR water level in the Chongqing area is not more than 0.11 m, which indicates no significant effect on the upstream reservoir area. Comparing the various scheduling schemes, when the flood diversion areas are not used, it is believed that the TGR can execute safe flood control for a 1,000‐year flood, thereby greatly reducing flood damage.  相似文献   

北黄海海底麻坑群形态的定量研究及控制因素   总被引：1，自引：0，他引：1  

刘晓瑜  冯秀丽  陈义兰  唐秋华  刘乐军  路波  焦鹏飞 《海洋学报》2018,40(3):36-49

本文基于高分辨率多波束水深数据和反向散射强度数据，对北黄海海底麻坑群的形态参数进行定量研究，结合水深、地形坡度和后向散射强度的变化准确界定了麻坑的轮廓，识别出圆形、椭圆形、拉长型麻坑共282个，并在ArcGIS软件中对其形态参数进行了分析计算，麻坑的平均长轴1.36 km，短轴0.78 km，直径0.94 km，面积0.88 km2，平均周长3.82 km，长宽比1.83，深度0.3~2.5 m，平均面积密集度13%，麻坑的剖面形态有麻坑边缘凹陷、中部有明显凸起（W1型），麻坑边缘凹陷、中部略凸起（W2型），麻坑中部单纯凹陷（V型），分别集中分布在麻坑群的北部、南部、西部。麻坑的平面规模大、深度小的原因与地层中形成麻坑的游离气体浓度较小有关，也可能受到了地震、海啸等外力的诱发。麻坑的长轴优势走向为ENE-WSW、NNE-SSW，底流对其形状的塑造起了较大作用，部分麻坑成串排列，形成串珠状的麻坑链，其排列方式受到海底古河道、古潟湖等沉积地层结构的控制。海底麻坑群发育区反向散射强度为-60~-71 dB，麻坑内部较麻坑外部平均高5 dB，可能为麻坑内部气体泄漏引起海底沉积物被剥蚀后残留下的粗颗粒物质或海底生物活动留下的遗迹导致的。  相似文献   

潮流界以下河段航道整治水位确定方法研究——以长江江阴以下河段为例     

徐元  贾雨少 《海洋工程》2018,36(2):64-72

在总结分析现有整治水位确定方法的基础上,根据潮流界以下河段的水沙运动特性,本文提出一种基于输沙能力的航道整治水位确定方法。考虑上游来水、下游潮汐为独立事件,统计潮流界以下河段上游来水、下游潮汐不同等级组合出现的频率,采用数学模型计算相应组合下河段沿程的潮位、流速过程,以流速四次方代表水流的输沙能力,统计不同潮位等级对应的综合净输沙能力,确定最大综合净输沙能力对应的水位为(最优)航道整治水位。以长江下游白茆沙水道和福姜沙水道为例,计算了所在河段的航道整治水位,并探讨了起动流速对整治水位计算的影响和最高整治水位概念对工程的意义。  相似文献   

高精度直升机机载LiDAR在高速公路改扩建勘测中的应用可行性研究          下载免费PDF全文

郑伟安 《山东国土资源》2018,34(8)

机载LiDAR在公路勘测方面的用途日益广泛。该文对直升机机载LiDAR在高速公路改扩建中的应用技术路线可行性进行了研究论证,从地面控制测量、点云数据获取、点云数据处理、成果应用等多个方面进行了阐述,通过分析LiDAR点云数据在5种不同地面控制点布设方案校正下的点云数据精度,论证了利用地面控制点对直升机机载LiDAR点云数据进行平面和高程校正的可行性。  相似文献   

内蒙古鲁新井田水文地质条件研究          下载免费PDF全文

赵志强  安美艳  高奎锋  王兆亮  王福芝 《山东国土资源》2018,34(6)

矿产资源开发导致了地下水失衡,地下水失衡又给矿产开发造成了极大的安全隐患,近年来,矿产资源开发与地下水环境保护之间的矛盾愈发凸显。通过对内蒙古鲁新井田典型的水文地质条件进行分析研究,分析采矿导致地下水失衡机理,深入剖析矿井开采充水条件及矿山开发对地下水环境的影响,合理提出了促进矿产开发与地下水保护相互协调的对策建议,为实现"采矿保水"协调统一提供了基础地质依据。为类似地区矿产开发过程中遵循自然规律,趋利避害,保障生产安全,保护地下水环境安全,实现资源绿色开发有较好的指导借鉴作用。  相似文献