大兴安岭南段锡的成矿作用：以黄岗-甘珠尔庙地区为例     

徐巧 《地质与勘探》2023,59(2):271-284

大兴安岭南段是我国重要的锡多金属成矿集中区,为促进区域锡多金属找矿突破,以在黄岗-甘珠尔庙地区多年的野外调查研究工作为基础,运用年代学测试、化学分析及地质模型等方法,分析了区域锡的成矿作用。认为二叠统基底地层及锡林郭勒杂岩是成矿物质的初始来源,经历的变质过程具有进一步富集的作用,大部分锡矿均遭受了多期次的火山-岩浆活动,最终决定锡多金属成矿的是燕山期酸性岩浆-热液成矿作用。同时成矿作用还受到控岩控矿构造、围岩性质、氧化-还原条件、开放-封闭环境的制约,认为在氧化性花岗岩浆侵入钙质地层条件下成矿作用以铁锡为主;还原性岩浆在侵入具开放性特征的围岩时,成矿作用以花岗岩外带围岩中的热液型脉状锡矿为主,而在侵入具封闭性特征的围岩时,成矿作用以花岗岩内带岩浆凸起部位的花岗岩型锡矿为主。因此,建议将主攻矿种由铅锌调整为锡银,部署重砂及化探方法圈定异常,针对硫化矿体部署电法,针对隐伏岩体部署磁法与重力,还可部署烃、汞、氧气测量等非常规化探方法预测隐伏岩体。  相似文献   

河南鲁山地区太华杂岩LA-ICP-MS锆石U-Pb年代学及其地质意义     

董猛猛  王长明  姚恩亚  贺昕宇  夏锦胜  王乔  陈晶源  王长侬  杨立飞  杜斌  石康兴 《岩石矿物学杂志》2018,37(1):1-18

华北克拉通是我国最大且最古老的克拉通,是研究太古宙岩浆活动和构造演化的理想区域,一直备受地质学家的关注。太华杂岩是华北克拉通的重要组成部分,主要分布在其南缘,总体呈近北西西-南东东向分布。在详细野外地质调查的基础上,对鲁山地区太华杂岩中的斜长角闪岩样品进行了LA-ICP-MS锆石U-Pb定年,以揭示其成岩及变质事件时代。样品的锆石U-Pb加权平均207Pb/206Pb年龄为2 788±16、2 714±12和1 920±18 Ma,分别代表斜长角闪岩成岩年龄、早期变质事件年龄及晚期变质事件年龄。综合梳理前人的锆石U-Pb年代学及Hf同位素研究数据,分析并讨论了3次地质事件的地质意义:2 850~2 700 Ma为一期重要的岩浆事件,代表了太古宙新生地壳的形成;2 800~2 600和~1 900 Ma为两期变质事件,期间太华杂岩分别遭受新太古代和古元古代两次变质变形改造。本次研究不仅可以解释太华杂岩的形成、变质时代及其地质意义,而且为进一步研究华北克拉通南缘乃至整个华北克拉通的形成与演化过程提供了新的数据资料。  相似文献   

基于子流域特征的泥石流易发性评价   总被引：1，自引：0，他引：1       下载免费PDF全文

张书豪  吴光  张乔  高飞 《水文地质工程地质》2018,(2):142-149

文章以云南省迪庆藏族自治州金沙江河谷金江镇—林当可为例,研究了基于子流域单元的泥石流易发性评价模型。首先,将研究区划分为1 570个子流域单元,其中70%(1 090个)用于模型建立,30%(480个)作为模型测试样本。然后,采用9种子流域单元特征因子（melton比率、流域平均径流侵蚀力指数、平均地形湿度指数、流域延伸率、流域平均高程、流域水系密度、流域平均植被覆盖度、流域平均坡度、流域高差率）的归一化值作为自变量,泥石流是否发育作为因变量,运用逻辑回归建立泥石流易发性评价模型,将易发性划分为5个等级。最后,通过独立的测试样本验证,易发性评价模型预测性能(AUC=0.821)良好;且随着易发性等级提高,泥石流绝对和相对发育比例逐级增加,模型满足合理性要求,适用于研究区的泥石流易发性评价。  相似文献   

Review of the Seabed Sediment Resuspension by Internal Solitary Wave     

Zhuangcai Tian  Xiujun Guo  Le Yu  Yonggang Jia  Shaotong Zhang  Luzheng Qiao 《地球科学进展》2018,33(2):166-178

Internal Solitary Waves (ISWs) are nonlinear, large amplitude motions of the interface between two fluids with different densities in the stratified ocean. Because of their strong vertical and horizontal current velocity, and the vortex, turbulent mixing caused by breaking, they affect marine environment, seabed sediment and man-made structures in the ocean. In the paper, we systematically analyzed and summarized the ISW-induced shoaling break mechanisms, models of suspension, and seabed dynamical response. Then, we discussed the ISW-induced sediment resuspension criteria, forming bottom and intermediate nepheloid layer and the capacity to suspend sediments in the seabed, and further put forward the unsolved problems based on the conducted work and related achievements. In shallow seas with complex terrain variations, shoaling can cause ISWs to deform, break, and split. Studies on the propagation of ISWs of depression over sloping topography have shown that an adverse pressure gradient causes the rotation of the flow separation, which produces vortices, and this results in global instability of the boundary layer and ISW burst. The separation vortices increase the bottom shear stress, vertical velocity, and near-bottom Reynolds stress, which leads to sediment resuspension and transport in the flow and vortex core. Although episodic, ISW-induced resuspension is hypothesized to be important enough to shape the topography. Shoaling ISWs may erode, resuspend and transport mud-like sediments, first towards shore by boluses, and subsequently offshore through the generation of intermediate nepheloid layers. Shoaling ISWs might be an important mechanism of muddy sediment dispersal along continental shelves. Furthermore, recent hypotheses suggest that sediment mobilization and transport caused by internal waves in general, and ISWs in particular, may be at the origin of some sedimentary structures found in the sedimentary rock record and also the hummocky-cross stratification. Observed on-shelf propagating frontal ISW most likely interacts with the sand waves, sediment waves or sand dunes. ISWs contribute to their generation, as they are trailed by considerable shear-induced turbulence and high-frequency internal waves close to the buoyancy frequency. This work is of great value for further understanding the process of ISW-induced sediment resuspension, transportation, and the capacity to suspend sediments in the seabed. It helps further study of the dynamic process of marine ecological environment dynamic process by ISW and the deep sea sedimentation process.  相似文献   

辽宁农居建筑物结构类型解译标志的分析研究     

于浩  庞巧  周小龙 《测绘与空间地理信息》2021,44(10):108-112,115

以实地调研数据为基准,对辽宁农居建筑物开展结构类型划分,利用无人机航拍影像建立影像特征与实际地物的对应关系,建立特征关联制定解译标志,依据解译标志定量提取无人机影像数据,最后通过Kappa系数分析法开展一致性分析验证.结果表明:辽宁农居房屋建筑结构类型分为土木砖石木结构、砖木结构、约束砌体结构及其他(厂房)结构,不同地域结构类型总体特点是辽西北、大连地区土木砖石木结构占比较大,辽南中部地区以约束砌体结构为主,沈抚、辽北地区以砖木结构为主.无人机影像解译一致性系数Kappa=0.723,具有高度的一致性,用此类方法获得解译标志具备一定的可行性,对提高该地区震后的快速评估的准确性具有重大的现实意义.  相似文献   

Identification of the Concealed Structures in the Beiya Area of Western Yunnan     

WANG Qiao  YANG Jian  YAO Wen  YANG Junbo 《《地质学报》英文版》2015,89(5):1779-1780

<正>The interpretation of regional gravity and magnetic data,especially the extracted information about concealed targets and structures,provide important evidence for geological structure research,oil-gas resource assessment,mineral potential forecast and prospective area delineation.Several interpretation methods have been  相似文献   

基于BP神经网络与变形监测成果的隧道安全状态评估     

黄惠峰  张献州  张拯  刘龙  喻巧  乐亚南 《测绘工程》2015,(3):53-58

隧道变形监测周期长、内容多且影响因素复杂,因此需要对隧道监测方法进行不断的改进,对隧道的健康状态进行实时评估。研究变形监测范畴内基于BP神经网络的隧道安全状态评估模型,组建集卫星定位技术、测量机器人、传感器技术、移动网络通信等为一体的现代化物联网模式下的隧道变形监测系统,分析多源数据的变形特征,结合专家经验知识,实现基于BP神经网络与变形监测成果下的隧道安全状态评估,为隧道变形监测及安全状态评估提供一种新颖而有效的方法。  相似文献   

天文观测数据开放共享政策与策略分析研究   总被引：1，自引：0，他引：1  

万望辉  崔辰州  乔翠兰  赵永恒  郝晋新  薛艳杰 《天文研究与技术》2015,(3)

当代天文学已经进入数据密集型和数据驱动的时代。随着我国天文学研究的不断发展,国内自产的天文观测数据呈现爆炸式增长的趋势。将天文观测数据资源集成并推动数据资源与应用服务的共建共享,建立健全符合科学发展规律的数据资源开放共享政策与制度,使天文科技资源得到高效有序的管理和使用,对国内天文学研究和科普教育的发展至关重要。在充分调研各国政府、部门和国际组织有关政策的基础上,剖析了国外科学数据"完全与公开"的共享原则,介绍了我国科学数据共享有关的管理规定和当前状况,重点论述国际各大天文望远镜项目和天文数据中心天文观测数据资源开放共享的有关政策。对国内天文观测数据资源和开放共享的现状以及存在的问题进行了分析和总结。对我国天文观测数据资源共享工作发展和政策制定提出了具体建议。  相似文献   

Estimation of extreme marine hydrodynamic variables in western Laizhou Bay     

Dai  Yanchen  Qiao  Lulu  Xu  Jishang  Zhou  Chunyan  Ding  Dong  Bi  Wei 《中国海洋大学学报(英文版)》2015,14(3):425-432

Laizhou Bay and its adjacent waters are of great importance to China's marine oil and gas development. It is therefore crucial to estimate return-period values of marine environmental variables in this region to ensure the safety and success of maritime engineering and maritime exploration. In this study, we used numerical simulations to estimate extreme wave height, sea current velocity and sea-level height in western Laizhou Bay. The results show that the sea-level rise starts at the mouth of the bay, increases toward west/southwest, and reaches its maximum in the deepest basin of the bay. The 100-year return-period values of sea level rise can reach 3.4–4.0 m in the western bay. The elevation of the western part of the Qingdong Oil Field would remain above the sea surface during extreme low sea level, while the rest of the oil field would be 1.6–2.4 m below the sea surface. The return-period value of wave height is strongly affected by water depth; in fact, its spatial distribution is similar to the isobath's. The 100-year return-period values of effective wave height can be 6 m or higher in the central bay and be more than 1 m in the shallow water near shore. The 100-year return-period values of current velocity is about 1.2–1.8 m s-1 in the Qingdong Oil Field. These results provide scientific basis for ensuring construction safety and reducing construction cost.  相似文献   

Assessment of urban effect on observed warming trends during 1955–2012 over China: a case of 45 cities     

Kai Jin  Fei Wang  Deliang Chen  Qiao Jiao  Lei Xia  Luuk Fleskens  Xingmin Mu 《Climatic change》2015,132(4):631-643

  相似文献