次摸地古滑坡运动特征反演分析     

胡剑 《工程地质学报》2014,22(3):361-365

以雅砻江次摸地古滑坡体为研究对象,经过现场地质调查,从地形地貌,地震记录及物质结构等地质条件对古滑坡的稳定性进行了宏观地质评价。认为在自然状态下古滑坡处于稳定状态,稳定性主要受控于引起初始滑动的基覆界面和体内潜滑面,同时,经过古滑坡前后形态变化的推演分析,根据能量法,滑坡运动学和谢德格尔假说,确定了4个关键的滑坡运动参数:滑坡半径r,等效坡度,综合动摩擦角和最大滑速Vmax 对应的后缘落差Hm。其中后缘落差Hm的取值分两种方法:（1）认为滑坡出现最大滑速Vmax 时后缘点停止运动,最大滑速Vmax 对应的Hm为滑动前后滑坡后缘点的垂直落距,（2）认为最大滑速Vmax 出现时后缘点和坡体会开始减速运动到静止,因此最大滑速Vmax 对应的Hm小于滑动前后滑坡后缘点的垂直落距,需要通过假设圆弧滑动面和滑坡运动学公式求出。最终本文推算出滑坡属于高速滑坡,最大滑速Vmax 在13.50～21.20ms-1 之间,并对古滑坡高速失稳的地质条件特征进行了分析。这对次摸地古滑坡附近工程地质背景相近的斜坡稳定性评价有一定借鉴意义。  相似文献   

Metallogeny of the Shilu Fe–Co–Cu deposit,Hainan Island,South China: Constraints from fluid inclusions and stable isotopes     

《Ore Geology Reviews》2014

The Shilu deposit is a world-class Fe–Co–Cu orebody located in the Changjiang area of the western part of Hainan Island, South China. The distribution of Fe, Co, and Cu orebodies is controlled by strata of the No. 6 Formation in the Shilu Group and the Beiyi synclinorium. Based on a petrological study of the host rocks and their alteration assemblages, and textural and structural features of the ores, four mineralization stages have been identified: (1) the sedimentary ore-forming period; (2) the metamorphic ore-forming period; (3) the hydrothermal mineralization comprising the skarn and quartz–sulfide stage; and (4) the supergene period. The fluid inclusions in sedimentary quartz and/or chert indicate low temperatures (ca. 160 °C) and low salinities from 0.7 to 3.1 wt.% NaCl_eq, which corresponds to densities of 0.77 to 0.93 g/cm³. CO₂-bearing or carbonic inclusions have been interpreted to result from regional metamorphism. Homogenization temperatures of fluid inclusions for the skarn stage have a wide range from 148 °C to 497 °C and the salinities of the fluid inclusions range from 1.2 to 22.3 wt.% NaCl_eq, which corresponds to densities from 0.56 to 0.94 g/cm³. Fluid inclusions of the quartz–sulfide stage yield homogenization temperatures of 151–356 °C and salinities from 0.9 to 8.1 wt.% NaCl_eq, which equates to fluid densities from 0.63 to 0.96 g/cm³.Sulfur isotopic compositions indicate that sulfur of the sedimentary anhydrite and Co-bearing pyrite, and the quartz–sulfide stage, was derived from seawater sulfate and thermochemical sulfate reduction of dissolved anhydrite at temperatures of 200 °C and 300 °C, respectively. H and O isotopic compositions of the skarn and quartz–sulfide stage demonstrate that the ore-forming fluids were largely derived from magmatic water, with minor inputs from metamorphic or meteoric water. The Shilu iron ore deposit has an exhalative sedimentary origin, but has been overprinted by regional deformation and metamorphism. The Shilu Co–Cu deposit has a hydrothermal origin and is temporally and genetically associated with Indosinian granitoid rocks.  相似文献   

一种改进的MAD钟差粗差探测方法          下载免费PDF全文

黄博华  杨勃航  李明贵  郭忠楷  茅健佑  王宏 《武汉大学学报(信息科学版)》2022,47(5):747-752

针对传统中位数绝对偏差（median absolute deviation,MAD）方法在探测钟差粗差方面的不足,提出一种改进的MAD钟差粗差探测方法。以一次差分数据为研究对象,通过深入分析传统MAD方法的工作原理,发现传统MAD方法的数学模型表达存在歧义。在优化探测模型结构的基础上,基于岭回归的基本原理,生成动态MAD,有效克服了部分具有显著趋势变化特征的钟差一次差分数据对粗差探测的干扰。使用国际全球卫星导航系统服务组织提供的GPS精密钟差数据进行了实验,并与传统MAD方法进行比较,结果表明,所提方法相较于传统的MAD方法在粗差探测准确率和查全率方面具有明显优势,实际应用价值较高。  相似文献   

In situ cultivation of deep-sea water with bicarbonate fueled a different microbial community     

Yong Wang  Jun Li  Zhanfei Wei  Qingmei Li  Yingli Zhou  Wenli Li  Jun Chen  Suixue Wang  Yongzhi Xin  Aiqun Zhang 《海洋学报(英文版)》2022,41(12):98-104

Some deep-sea microbes may incorporate inorganic carbon to reduce CO₂ emission to upper layer and atmosphere. How the microbial inhabitants can be affected under addition of bicarbonate has not been studied using in situ fixed and lysed samples. In this study, we cultivated 40 L natural bottom water at ~1 000 m depth with a final concentration of 0.1 mmol/L bicarbonate for 40 min and applied multiple in situ nucleic acids collection (MISNAC) apparatus for nucleic acids extraction from the cultivation. Our classification result of the cultivation sample showed a distinct microbial community structure, compared with the samples obtained by Niskin bottle and six working units of MISNAC. Except for notable enrichment of Alteromonas, we detected prevalence of Asprobacter, Ilumatobacter and Saccharimonadales in the cultivation. Deep-sea lineages of Euryarchaeota, SAR406, SAR202 and SAR324 were almost completely absent from the cultivation and Niskin samples. This study revealed the dominant microbes affected by bicarbonate addition and Niskin sampling, which suggested rapid responses of deep-sea microbes to the environmental changes.  相似文献   

聚焦波作用下平面网衣结构的水动力特性研究     

俞嘉臻  张显涛  李欣 《海洋工程》2022,40(5):98-110

由于沿海区域的限制以及愈加严重的环境污染,渔业养殖正从近海走向深远海。深远海海域的海况更加恶劣,给养殖装备的设计与性能评估带来新的挑战。为解决该问题,对极端波浪与养殖装备网衣结构的相互作用开展研究。基于waves2Foam建立数值波浪水池,极端波浪模拟采用基于NewWave理论的聚焦波模型,网衣结构模拟采用多孔介质模型,并通过与Morison模型计算的网衣受力等效分析,获得多孔介质模拟网衣结构阻力系数的直接估计方法。然后将多孔介质模型嵌入waves2Foam中,开展聚焦波与网衣结构相互作用的数值模拟,同时开展水槽试验,验证数值模拟的准确性。基于数值模拟结果,系统地分析了不同网衣密实度及不同波浪参数下网衣结构的升阻力特性以及网衣结构对波浪场的扰动规律。研究表明：聚焦波波峰幅值和网衣密实度对网衣结构的升阻力影响较大,且升力峰值出现在阻力为0的时刻;网衣结构对聚焦波的时空演化特性有影响,改变了聚焦波波形。  相似文献   

Crust and upper mantle structure and its tectonic implications in the South China Sea and adjacent regions     

《Journal of Asian Earth Sciences》2013

We present a 3D S-velocity model for the crust and upper mantle of the South China Sea and the surrounding regions, constrained from the analysis of over 12,000 of fundamental Rayleigh wave dispersion curves between 10 s and 150 s periods. The lateral resolution was found to vary from 2° to 4° with the increasing period over the study region. A robust scheme of Debayle and Sambridge allowed us to conduct the tomographic inversion efficiently for massive datasets. Group velocity maps varying with period show lateral heterogeneities, well related to the geological and tectonic features in the study region. The 3D S-velocity model was constructed from the 1D structure inversion of the tomographic group velocity dispersion curves at each node. The obtained average crustal structure is similar to the PREM model, while the average mantle velocity is typically lower than the global average. The complicated 3D structures reveal three prominent features correlated with geological divisions: sea basin regions, island and arc regions, and continental regions. The derived crustal and lithospheric thicknesses range from ∼15 to >50 km and from ∼60 to >140 km, respectively, with the thinnest in the South China Sea, the thickest in eastern Tibet and the Yangtze Block, and the medium in the South China Fold Belt, Indochina, and island arc regions. Our results further confirm that (1) a Mesozoic subduction zone, which is interpreted as the tectonic weak zone during the Paleogene, exists along the South China margin; (2) the influence of the Indochina extrusion along the Red River Fault is limited for the South China Sea region; (3) there is a slab remnant of the proto-South China Sea beneath Borneo. New findings suggest that the Mesozoic subduction zone should be built into any evolution model for the region, as well as the other two major tectonic boundaries of the Red River Fault and proto-South China Sea subduction zone.  相似文献   

深海生物原位实验与生态监测研究进展          下载免费PDF全文

王勇  郑鹏飞  贺丽生  李俊  陈俊  高兆明  李文莉  张艾群 《应用海洋学学报》2022,41(3):543-553

深海在黑暗、高静水压、低温（黑烟囱等热液系统除外）和寡营养的极端环境下形成了特殊的生境。对深海生物/微生物的研究,不仅可以揭示各种深海生物的生理代谢特性和动态变化规律,而且有助于深海生物资源的开发利用,特别是深海微生物碳循环机制的相关研究可为全球实现碳中和目标提供新的路线图。研究深海生物的首要条件是获得大量保持原位特性的样本,然而传统深海采样手段的局限可能导致深海相关研究结果无法反映深海环境下真实的生命过程,亟需发展满足深海生物原位研究的采样方法和生态监测技术。本文对深海生物研究现状,相关科学问题和原位组学研究进展,以及原位生态监测装备研发和应用进行综述,并对深海原位生物实验室进行了展望。  相似文献   

楔挡分流结构爆炸损伤特征数值模拟   总被引：1，自引：0，他引：1  

王秀丽  靳毅虎  孟杰  朱思帅 《地震学刊》2013,(6):617-623,630

楔挡分流结构是一种新型的拦挡结构,在灾害防治中发挥着重要作用,对其在爆炸等特殊荷载作用下的损伤进行研究具有重要的意义。使用ANSYS／AUTODYN软件,首先采用光滑粒子流体动力学方法（smoothed particle hy-drodynamics,SPH）和混凝土的RHT（Riede-Hiermater-Thoma）本构,对前人试验模型进行了模拟计算。通过对试验和模拟结果的对比分析,验证了SPH算法和混凝土RHT本构在模拟混凝土介质中爆炸损伤的可行性。然后使用同样的算法和材料本构,建立全尺寸模型,对混凝土楔挡分流拦挡坝坝体内爆炸损伤及应力波传播进行了模拟计算。通过对计算结果的分析,研究了混凝土介质中爆炸成坑的机理,得到了楔挡分流结构在内部爆炸作用下的爆坑形态特征、药柱上下部混凝土损伤特点、破碎区范围。对坝体中冲击波传播及混凝土碎块抛射等问题进行了探索。  相似文献   

密斑刺鲀(Diodon hystrix)gnrh基因的克隆及表达分析     

陈华谱  黄春仁  何睿祺  戴明姝  张明真  李智渊  黄海  李广丽 《海洋与湖沼》2021,52(4):994-1006

密斑刺鲀(Diodonhystrix)不仅具有食用价值,同时也是传统的中药及保健食品,但目前关于密斑刺鲀的生殖内分泌调控研究较少,限制了密斑刺鲀的人工繁育基础理论的发展。总所周知,促性腺激素释放激素(gonadotropin-releasing hormone, GnRH)是生殖内分泌调控的关键因子之一。利用转录组分析及分子克隆技术,获得密斑刺鲀促性腺激素释放激素(gonadotropin-releasinghormone,GnRH) gnrh2和gnrh3基因的cDNA开放阅读框(Open Reading Frame, ORF)序列,并利用生物信息学的方法,获得密斑刺鲀gnrh2 cDNA开放阅读框共279 bp,可编码92个氨基酸残基;密斑刺鲀gnrh3cDNA开放阅读框共270 bp,可编码89个氨基酸残基。通过系统进化分析表明,密斑刺鲀GnRH与鲀科类的鱼具有较近的亲缘关系。通过聚合酶链式反应(Polymerase Chain Reaction, PCR)半定量的方法检测gnrh2和gnrh3基因在密斑刺鲀各组织中的分布,结果发现gnrh2和gnrh3基因在脾、鳃和垂体中的表达量较高,而在心脏中的表达量最低。此外,利用实时荧光定量的方法检测了密斑刺鲀gnrh2和gnrh3基因在性腺发育不同时期的表达模式,结果显示密斑刺鲀gnrh2基因在不同的性腺发育时期中没有显著性的变化,而gnrh3基因随着性腺发育成熟而不断升高。研究主要获得两个创新性的重要结果:首先是证实了密斑刺鲀存在两种gnrh基因(gnrh2和gnrh3),其次是提示了gnrh3基因可能是密斑刺鲀生殖调控的主要gnrh类型。研究结果可为深入研究密斑刺鲀生殖内分泌调控机理提供研究方向和基础。  相似文献   

基于多源遥感数据的大襟岛海域叶绿素a反演及富营养化评价          下载免费PDF全文

熊一璇  麻书畅  张霄宇  黄国容  陈嘉星  韩亚超 《海洋学研究》2021,39(2):43-51

本研究基于实测的Chl-a质量浓度和海表面光谱数据,构建了适用于CASI(Compact Airborne Spectrographic Imager)航空高光谱和MODIS(Moderate-resolution Imaging Spectroradiometer)卫星遥感影像的Chl-a反演模型,并在研究海域开展了Chl-a质量浓度的反演。研究结果表明,基于CASI影像的波段比值模型可以较好地反演出研究海域的Chl-a质量浓度,研究海域内Chl-a含量为0.1~4.4 μg/L,平均相对误差为14.58%;基于MODIS卫星影像反演获得的珠江口Chl-a质量浓度为0~8 μg/L,平均相对误差为17%。总体而言,大襟岛海域整体Chl-a质量浓度的分布比较均匀,而且含量较低;基于Chl-a质量浓度计算获得卡尔森营养状态指数表明,研究海域处于贫营养化和中营养化水平,复杂水动力环境和高浊度可能是抑制研究海域浮游植物生长的主要因素。  相似文献