基于多元信息约束的隐伏矽卡岩型铁矿床的定位——以云南北衙金矿区红泥塘矿段为例          下载免费PDF全文

王桥  王绪本  杨剑  闵刚  郭镜 《地球物理学报》2016,59(12):4771-4781

矽卡岩型矿床是云南北衙金多金属矿区的一种主要矿床类型,受岩体、构造及层位等控制,其有利找矿空间为中酸性岩体与碳酸盐岩的接触带.以岩石物性为纽带,实现目标地质体与地球物理场的转换,提取有效信息.接触带中低电阻率、岩体的低密度性、铁矿的高磁性和高极化率等都是矽卡型铁矿床的特有地球物理属性.通过地质地球物理等多元信息的层层约束,解析不同级次的成矿要素问题,实现对隐伏矽卡岩型铁矿床的定位,建立地球物理勘探模式,并在矿区外围开展方法有效性的验证,取得了良好的勘探效果,提出一套适应于北衙地区及类似成矿地质背景下的隐伏矽卡岩型铁矿床定位预测方法.  相似文献   

基于网络约束方法的交通事故空间点格局分析     

聂可  王振声  杜清运  张玉茜 《地理信息世界》2017,(6):50-56

研究一种基于路网约束空间格局方法在交通事故分析中的应用,以武汉市13个区交通事故为研究对象,将交通事故抽象成道路网上的点要素,采用路网约束下的核密度估计方法,讨论其空间分布格局并与平面空间点聚类分析的结果进行对比分析,最后采用局部Moran's Ⅰ方法对道路基本单元网络核密度估计结果值进行判别,揭示0.01显著性水平下的武汉交通事故易发路段。实验结果表明,网络核密度估计算法可直观体现事故沿城市道路网的聚类模式,对核密度结果进行的局部Moran's Ⅰ统计方法能够有效地应用于易发路段的鉴别。  相似文献   

扬子块体与华北块体在海区的接触关系——来自上下源、长排列多道地震剖面的新认识   总被引：4，自引：4，他引：0       下载免费PDF全文

吴志强  郝天珧  张训华  刘丽华  肖国林  温珍河 《地球物理学报》2015,58(5):1692-1705

在新一轮南黄海区域地质地震调查工作中,针对地震地质条件和勘探目标,设计了新的地震资料采集技术方案——上下源延迟激发+长排列接收,获得了强反射界面之下的深部地层有效反射,揭示了千里岩断裂两侧分布着向南逆冲的构造推覆带.结合重力、磁力反演成果认为,千里岩隆起区为扬子块体与华北块体碰撞接触带,扬子块体向北运动与华北块体碰撞后楔入到华北块体之中.  相似文献   

锆石成因矿物学与锆石微区定年综述   总被引：54，自引：0，他引：54  

李长民 《华北地质》2009,32(3):161-174

锆石是岩浆岩、变质岩和石英脉型金矿床中的一种常见副矿物,对锆石成因类型的准确判断是正确理解锆石U-Pb年龄意义的关键.本文中笔者对不同成因类型锆石的判别标志及年龄意义进行系统的总结,并认为将锆石的阴极发光图像(CL)、背散射电子图像(BSE)、痕量元素组成及矿物包裹体特征的研究相结合是进行锆石成因鉴定的有效方法.近年来同位素质谱技术的发展使得人们对同一锆石颗粒内部不同成因类型的锆石晶域进行原位年龄测定成为可能.通过微区原位定年技术,能够给出有关寄主岩石的地质演化历史等重要信息,这可以为地质过程的精细年代学格架的建立提供有效的证据.来自不同类型岩石中的锆石可能经历了Pb的扩散丢失作用、晶格损伤导致的蜕晶化作用以及变质重结晶作用.这些过程对锆石计时的准确性和有效性带来了不同程度的影响.为了对测定锆石年龄的地质意义进行合理解释,在进行锆石U-Pb定年前,必需对锆石进行成因矿物学和矿物内部结构的深入研究,特别是阴极发光和背散射电子成像研究,通过内部结构特征确定锆石的成因类型和形成环境.笔者认为,组成单一的岩浆锆石是理想的U-Pb定年对象,变质重结晶锆石域常是重结晶锆石和继承晶质锆石的混合区,容易给出混合年龄,只有变质增生锆石和完全变质重结晶锆石才能给出准确的变质时代,而从继承锆石中鉴别出的热液锆石可以获得可靠的流体活动时间.  相似文献   

Using postglacial sea level, crustal velocities and gravity-rate-of-change to constrain the influence of thermal effects on mantle lateral heterogeneities   总被引：3，自引：0，他引：3  

Hansheng Wang  Patrick Wu  Wouter van der Wal   《Journal of Geodynamics》2008,46(3-5):104

Lateral heterogeneities in the mantle can be caused by thermal, chemical and non-isotropic pre-stress effects. Here, we investigate the possibility of using observations of the glacial isostatic adjustment (GIA) process to constrain the thermal contribution to lateral variations in mantle viscosity. In particular, global historic relative sea level, GPS in Laurentide and Fennoscandia, altimetry together with tide-gauge data in the Great Lakes area, and GRACE data in Laurentide are used. The lateral viscosity perturbations are inferred from the seismic tomography model S20A by inserting the scaling factor β to determine the contribution of thermal effects versus compositional heterogeneity and non-isotropic pre-stress effects on lateral heterogeneity in mantle viscosity. When β = 1, lateral velocity variations are caused by thermal effects alone. With β < 1, the contribution of thermal effect decreases, so that for β = 0, there is no lateral viscosity variation and the Earth is laterally homogeneous. These lateral viscosity variations are superposed on four different reference models which differ significantly in the lower mantle viscosity. The Coupled Laplace Finite Element method is used to predict the GIA response on a spherical, self-gravitating, compressible, viscoelastic Earth with self-gravitating oceans, induced by the ICE-4G deglaciation model.Results show that the effect of β on uplift rates and gravity rate-of-change is not simple and involves the trade-off between the contribution of lateral viscosity variations in the transition zone and in the lower mantle. Models with small viscosity contrast in the lower mantle cannot explain the observed uplift rates in Laurentide and Fennoscandia. However, the RF3S20 model with a reference viscosity profile simplified from Peltier's VM2 with the value of β around 0.2–0.4 is found to explain most of the global RSL data, the uplift rates in Laurentide and Fennoscandia and the BIFROST horizontal velocity data. In addition, the changes in GIA signals caused by changes in the value of β are large enough to be detected by the data, although uncertainty in other parameters in the GIA models still exists. This may encourage us to further utilize GIA observations to constrain the thermal effect on mantle lateral heterogeneity as geodetic and satellite gravity measurements are improved.  相似文献   

Lu-Hf同位素体系对若干基础地质问题的新制约(之一)--地球早期演化   总被引：3，自引：0，他引：3  

凌文黎  程建萍 《地质科技情报》1999,(1)

Ｌｕ－Ｈｆ同位素方法已趋成熟,主要得益于其化学方法的极大改进和与之配套的高电离率质谱仪的使用。Ｌｕ－Ｈｆ同位素方法在地球的早期性质研究中表明,部分古太古代片麻岩Ｓｍ－Ｎｄ同位素体系所记录的早期地幔的“极度”亏损,实际是对其同位素体系热扰动的反映;关于大陆地壳的生长模式,石英岩锆石Ｌｕ－Ｈｆ同位素特征支持了幕式增生的观点  相似文献   

Vegetation changes and sequential flowering after rain in the southern Atacama Desert     

Patricia E. Vidiella  Juan J. Armesto  Julio R. Gutirrez 《Journal of Arid Environments》1999,43(4):449

We describe the changes in plant cover, species richness, and flowering after rainfall over an entire growing season (September 1989–January 1990) in a southern Atacama Desert site in Chile. One month after the rain, vegetation was dominated by annuals and geophytes which dried out after 19 weeks. Among all species, including shrubs, we found differences of 4–10 weeks in the length and peak of the flowering period. The flowering sequence of the species belonging to the families Brassicaceae, Liliaceae, Onagraceae, and Asteraceae matched closely the sequences described for temperate plant communities, suggesting that this phenological character is phylogenetically determined.  相似文献   

不定乘子在完整与非完整力学系统中的作用     

张建刚 《广东海洋大学学报》1995,(1)

归纳总结了不定乘子的由来、意义和作用，提出在非完整力学系统中，不定乘子的引入是解决问题的一把钥匙。  相似文献   

Stochastic inversion for scaling geology     

M. Pilkington  J. P. Todoeschuck 《Geophysical Journal International》1990,102(1):205-217

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3D reconstruction from a single image using geometric constraints   总被引：2，自引：0，他引：2  

Frank A. van den Heuvel 《ISPRS Journal of Photogrammetry and Remote Sensing》1998,53(6):354-368

Photogrammetry has many advantages as a technique for the acquisition of three-dimensional models for virtual reality. But the traditional photogrammetric process to extract 3D geometry from multiple images is often considered too labour-intensive. In this paper a method is presented with which a polyhedral object model can be efficiently derived from measurements in a single image combined with geometric knowledge on the object. Man-made objects can often be described by a polyhedral model and usually many geometric constraints are valid. These constraints are inferred during image interpretation or may even be extracted automatically. In this paper different types of geometric constraints and their use for object reconstruction are discussed. Applying more constraints than needed for reconstruction will lead to redundancy and thereby to the need for an adjustment. The redundancy is the basis for reliability that is introduced by testing for possible measurement errors. The adjusted observations are used for object reconstruction in a separate step. Of course the model that is obtained from a single image will not be complete, for instance due to occlusion. An arbitrary number of models can be combined using similarity transformations based on the coordinates of common points. The information gathered allows for a bundle adjustment if highest accuracy is strived for. In virtual reality applications this is generally not the case, as quality is mainly determined by visual perception. A visual aspect of major importance is the photo-realistic texture mapped to the faces of the object. This texture is extracted from the same (single) image. In this paper the measurement process, the different types of constraints, their adjustment and the object model reconstruction are treated. A practical application of the proposed method is discussed in which a texture mapped model of a historic building is constructed and the repeatability of the method is assessed. The application shows the feasibility of the method and the potential of photogrammetry as an efficient tool for the production of 3D models for virtual reality applications.  相似文献