Driftwood deposition from debris flows at slit-check dams and fans   总被引：3，自引：1，他引：2  

Badri Bhakta Shrestha  Hajime Nakagawa  Kenji Kawaike  Yasuyuki Baba  Hao Zhang 《Natural Hazards》2012,61(2):577-602

Experience shows that debris flows containing large woody debris (driftwood) can be more damaging than debris flows without driftwood. In this study, the deposition process of debris flows carrying driftwood was investigated using numerical simulations and flume experiments. Debris-flow trapping due to driftwood jamming in a slit-check dam was also investigated. A numerical model was developed with an interacting combination of Eulerian expression of the debris flow and Lagrangian expression of the driftwood, in which the fluctuating coordinates and rotation of the driftwood were treated stochastically. The calculated shapes and thicknesses of a debris-flow fan and the positions and orientations of the deposited driftwood on a debris-flow fan were consistent with experimental flume results. The jamming of driftwood in a slit-check dam was evaluated based on geometry and probability. The simulated results of outflow discharge and the proportion of driftwood passed through the slit-check dam also agreed with the experimental results.  相似文献   

Radioactive elements in natural gas: a case study on distribution of gaseous 222radon and its origin mechanism     

Haohan Luo  Dazhen Tang  Qituan Yan  Wei He  Hao Xu 《Natural Hazards》2012,63(2):647-657

As natural gas becomes increasingly important in our daily life, studies have been carried out on trace elements such as mercury and arsenic within it. Other than those, the existence of radioactive gaseous radon from the combustion of natural gas indoors can cause severe diseases and damages to body organs, putting a hazardous impact on human health. At the same time, the radon can also corrode gas production and transportation equipment. A review of the literature on radon concentrations in natural gas produced from gas reservoirs in China and other countries have been studied. Radon is a decay product from ²³⁸U, which is closely related to the accumulation and migration of organic matter during diagenesis. Gas recovered from reservoirs with higher than average natural ²³⁸U contains higher than average levels of ²²²Rn. Massive fault systems and fracture zones appear to play a significant role in radon concentrations in natural gas.  相似文献   

黑龙江乌拉嘎金矿的次火山岩浆-热液成矿:熔体-流体包裹体证据   总被引：4，自引：1，他引：3  

徐九华  魏浩  王燕海  曾庆栋  刘建明  王永彬  毛骞 《岩石学报》2012,28(4):1305-1316

黑龙江乌拉嘎金矿是我国陆相火山岩区的重要金矿之一。构造位置处于古亚洲构造域与滨太平洋构造域交接复合部位的东北缘,矿体主要分布于团结沟斜长花岗斑岩接触带部位的隐爆角砾岩带和黑龙江群变质岩的层间裂隙中。斜长花岗斑岩的石英斑晶中发育3类包裹体:熔体包裹体、原生的L-V包裹体(及少量的L-V-S包裹体)和次生的L-V包裹体。玻璃质熔体包裹体相当于酸性殘浆的成分(SiO2达69.5%～73.8%),其捕获温度大于800℃。石英斑晶中次生L-V包裹体均一温度集中在210～350℃、盐度5%～7%NaCleqv,代表了次火山岩浆热液的特征,与黄铁矿-早期白色玉髓状石英阶段中Q1的包裹体均一温度范围很接近,而盐度略高于白色玉髓状石英Q1的。乌拉嘎金矿的金成矿可划分3个成矿阶段,发育盐水溶液包裹体:(1)黄铁矿-早期白色玉髓状石英阶段,包裹体均一温度为154～355℃,集中在190～330℃,盐度为1.3%～8.2%NaCleqv,密度为0.53～0.88g/cm3。(2)烟灰色玉髓状石英-多金属硫化物阶段,石英中包裹体均一温度为159～196℃,集中在170～190℃,盐度为2.2%～3.2%NaCleqv,密度0.79～0.92g/cm3。(3)碳酸盐-石英阶段,方解石中包裹体均一温度集中在170～270℃;盐度0.5%～2.9%NaCleqv。成矿流体以中低温、低盐度、贫CO2的盐水体系为特征,与国内外陆相火山-次火山热液矿床十分相似。石英斑晶中熔体、流体包裹体及其共存反映了次火山岩浆活动晚期,由硅酸盐熔体通过不混溶产生含矿的盐水溶液的可能,说明了金成矿与斑岩的成因联系,乌拉嘎金矿应该属于陆相火山-次火山活动有关的中低温浅成热液金矿床。  相似文献   

三塘湖盆地中二叠统原油的来源及其分布特征     

国建英  钟马宁  梁浩  李欣  王东良  马卫  崔会英  李谨 《地球化学》2012,41(3):266-277

在对三塘湖盆地中二叠统原油物性、生物标志物特征分析的基础上,开展了油岩生物标志物参数的对比和成藏主控因素的分析。研究认为,中二叠统芦草沟组原油属于自生自储、源内成藏。条湖组原油主要来自芦草沟组烃源岩,属于近源成藏;部分原油(马49井等)来自下二叠统-上石炭统,属于源外成藏。中二叠统的源岩油藏分布主控因素主要体现在源和裂缝两个方面,有效源岩(主要体现在源岩成熟度上)控制了油藏的分布;裂缝(构造裂缝为主)则是控制油藏产能的关键。因此,三塘湖盆地的原油勘探应围绕源和裂缝这两个方面进行,上述认识对油田中二叠统原油的勘探具有积极的指导意义。  相似文献   

华南西部新元古代中期沉积盆地性质及其动力学分析   总被引：3，自引：0，他引：3  

杨菲  汪正江  王剑  杜秋定  邓奇  伍浩  周小琳 《地质论评》2012,58(5):854-864

在桂北,新元古代丹洲群出露在九万大山至越城岭一带,为一套角度不整合在中——新元古界四堡群变质岩系之上,整合于南华冰期沉积之下的浅变质/未变质沉积岩夹火山岩组合。本文通过对罗城黄金丹洲群剖面的沉积相及沉积序列研究表明:白竹组至合桐组为冲洪积相(移地滨岸相)、三角洲相、浅海陆棚相、碳酸盐缓坡(台地)、深水陆棚相(或欠补偿盆地相)等沉积组合,拱洞组为深水浊积岩、浅海陆棚相沉积组合,晚期为滨浅海相或三角洲相组合。综合剖面沉积相、沉积层序以及其中多幕式的火山—岩浆活动等沉积记录分析,作者认为与新元古代新生沉积盆地开启相伴的双模式的、同期的、一系列大火成岩省的形成,沉积盆地早期的海侵上超和饥饿沉积,晚期差异沉降和快速充填,以及与盆地演化阶段相伴的幕式火山岩浆活动等一系列事实与弧陆碰撞模式是相矛盾的,丹洲群及其相当层位地层应为裂谷盆地充填序列,其盆地演化的阶段性可能是地幔柱幕式活动的沉积响应。  相似文献   

Paleo‐fires and Atmospheric Oxygen Levels in the Latest Permian: Evidence from Maceral Compositions of Coals in Eastern Yunnan,Southern China   总被引：1，自引：0，他引：1  

SHAO Longyi  WANG Hao  YU Xiaohui  LU Jing  ZHANG Mingquan 《《地质学报》英文版》2012,86(4):949-962

Inertinite maceral compositions of the Late Permian coals from three sections in the terrestrial and paralic settings of eastern Yunnan are analyzed in order to reveal the paleo-fire events and the atmospheric oxygen levels in the latest Permian. Although the macerals in the studied sections are generally dominated by vitrinite, the inertinite group makes up a considerable proportion. Its content increases upward from the beginning of the Late Permian to the coal seam near the Permian-Triassic boundary. Based on the microscopic features and the prevailing theory that inertinite is largely a by-product of paleo-fires, we suggest that the increasing upward trend of the inertinite abundance in the latest Permian could imply that the Late Permian peatland had suffered from frequent wildfires. Since ignition and burning depend on sufficient oxygen, a model-based calculation suggests that the O2 levels near the Wuchiapingian/Changhsingian boundary and the Permian-Triassic boundary are 27% and 28% respectively. This output adds supports to other discoveries made in the temporal marine and terrestrial sediments, and challenges the theories advocating hypoxia as a mechanism for the Permian-Triassic boundary crisis.  相似文献   

青藏高原困难地区开展区域重力调查工作遇到的问题与对策     

耿涛  刘宽厚  贺颢  孟军海  杨明生  高鹏  杜辉  田中英 《物探与化探》2012,(5):749-754

青藏高原的大部分地区自然条件恶劣、人口稀少、交通不便、基础测绘程度低、通讯条件极其落后,属于典型的开展区域重力调查工作的困难地区。在这些地区开展区域重力调查工作,在重力仪选择及标定、GPS控制点的建立及其控制范围、重力测点水准高程求取,以及近区地形改正、物性标本采集等方面都会遇到很多与内地一般地区工作时不一样的问题。笔者通过对青藏高原地区开展的多个1：20万区域重力调查项目的野外工作过程进行总结,分析了困难地区区域重力调查项目实施过程中遇到的一些技术问题,认为可通过尽量选择高精度、稳定性好的重力仪,合理延长闭合时间,采用CQG2000似大地水准面模型求取测点水准高程,扩大GPS基准站的控制半径等办法解决。这些措施可作为以后在青藏高原地区及国内其他困难地区开展区域重力调查工作时的参考。  相似文献   

A Super‐Large Tantalum and Niobium Ore Found in Inner Mongolia     

Hao Ziguo  Fei Hongcai  Liu Lian 《《地质学报》英文版》2012,86(2):531-531

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A New Species of Liadotaulius (Insecta: Trichoptera) from the Middle Jurassic of Daohugou,Inner Mongolia     

WU Hao  HUANG Diying 《《地质学报》英文版》2012,86(2):320-324

Diverse caddis flies are recently collected from the Middle Jurassic Daohugou fauna in Ningcheng County, Inner Mongolia, northern China, and different types of caddis cases have been reported in the same locality. A new species of caddisfly, Liadotaulius daohugouensis sp. nov. is described and illustrated; the establishment is based on a well-preserved isolated forewing collected from the Middle Jurassic Jiulongshan Formation of Daohugou. The family status of Liadotaulius is discussed on the basis of new material and is referred to the family Philopotamidae. The Daohugou fauna continues to provide new data for studying the early evolution of Trichoptera.  相似文献   

News and Highlights     

Hao Ziguo  Fei Hongcai  Liu Lian 《《地质学报》英文版》2012,86(4):1037-1038

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