Integration of natural data within a numerical model of ablative subduction: a possible interpretation for the Alpine dynamics of the Austroalpine crust     

M. RODA  M. I. SPALLA  A. M. MAROTTA 《Journal of Metamorphic Geology》2012,30(9):973-996

A numerical modelling approach is used to validate the physical and geological reliability of the ablative subduction mechanism during Alpine convergence in order to interpret the tectonic and metamorphic evolution of an inner portion of the Alpine belt: the Austroalpine Domain. The model predictions and the natural data for the Austroalpine of the Western Alps agree very well in terms of P–T peak conditions, relative chronology of peak and exhumation events, P–T–t paths, thermal gradients and the tectonic evolution of the continental rocks. These findings suggest that a pre‐collisional evolution of this domain, with the burial of the continental rocks (induced by ablative subduction of the overriding Adria plate) and their exhumation (driven by an upwelling flow generated in a hydrated mantle wedge) could be a valid mechanism that reproduces the actual tectono‐metamorphic configuration of this part of the Alps. There is less agreement between the model predictions and the natural data for the Austroalpine of the Central‐Eastern Alps. Based on the natural data available in the literature, a critical discussion of the other proposed mechanisms is presented, and additional geological factors that should be considered within the numerical model are suggested to improve the fitting to the numerical results; these factors include variations in the continental and/or oceanic thickness, variation of the subduction rate and/or slab dip, the initial thermal state of the passive margin, the occurrence of continental collision and an oblique convergence.  相似文献   

建设一流山地研究所的战略构想——写在成都山地所成立40周年之际     

邓伟  程根伟 《山地学报》2006,24(5):513-517

成都山地所走过了40年的发展历程，现在已经成为在山地灾害防治和山地环境保护方面的国家级研究机构。进入21世纪以来，山地所面临新的发展机遇和挑战，即如何更好地满足国家重大战略需求，更准确地把握世界科技前沿，不断地推动一流山地研究所的建设。其核心与关键就是要造就一支高水平的科研队伍，持续提升全所的创新能力，不断为山区可持续发展做出基础性、战略性和前瞻性科技贡献。本文是基于知识创新工程三期学科发展规划主要框架而成，提出了研究所学科发展的目标及基本举措。  相似文献   

Practical Influences of Geometric and Radiometric Image Quality Provided By Different Digital Camera Systems   总被引：1，自引：0，他引：1  

S. Robson  & M. R. Shortis 《The Photogrammetric Record》1998,16(92):225-248

Imaging systems founded on current digital camera technology are finding widespread use in high precision measurement applications. A single digital CCD camera, or an array of such cameras, equipped with ring lighting equipment is commonly used to acquire imagery of high contrast retroreflective targets placed on the object at discrete locations to signalize points of interest. The precise and accurate measurement of each imaged target location is a fundamental requirement if suitable measurement tolerances are to be obtained. Whilst such systems are undoubtedly capable of producing excellent results, the practical effects of target image quality on the photogrammetric measurement process is in need of careful consideration. This paper revisits some fundamentals of the optical imaging of retrotargets and investigates some abilities of a range of digital camera systems to provide images of retrotargets that are appropriate to the measurement process. Some experimental results are presented including the imaging of planar arrays of differing sized retrotargets at differing angles and exposures and a series of network analyses in which the level of target image intensity has been varied systematically.  相似文献   

基于相干目标的干涉图叠加方法监测天津地区地面沉降   总被引：2，自引：0，他引：2  

范景辉  郭华东  郭小方  刘广  葛大庆  刘圣伟 《遥感学报》2008,12(1):111-118

利用ENVISAT ASAR数据,采用基于相干目标的干涉图叠加方法,对天津地区的地面沉降现象进行了DInSAR监测试验.差分干涉处理采用"两轨法",使用校正了高程异常的SRTM DEM数据消除高程相位.以相干系数为标准选取了相干目标,解缠过程中运用了Delaunay三角剖分和权重最小费用流算法.本文获得的季度平均沉降速率图有效揭示了试验区地面沉降的空间展布及相对形变量,但其获得的绝对形变量尚需地面实测数据校验.  相似文献   

三湖坳陷第四系七个泉组层序地层及有利目标预测   总被引：2，自引：0，他引：2  

郭少斌  陈成龙 《地学前缘》2008,15(2):43-50

采用钻/测井、地震及米兰科维奇旋回相结合的方法,对柴达木盆地三湖坳陷第四系七个泉组进行了高分辨率层序地层学研究,在七个泉组可识别出6个层序界面,进而划分出5个三级层序。根据蒿藜花粉含量、碳酸盐含量、δ18O、GR、氯离子含量等对比分析,本区气候总体上由温暖变为干冷,存在5次温湿与干冷气候的次级旋回,分别对应sq1、sq2、sq3、sq4、sq5五个层序,每个旋回内部波动与基准面上升半旋回和基准面下降半旋回相一致。层序Ⅱ(sq2)基准面上升半旋回时期发育的三角洲前缘砂体尖灭及砂岩透镜体圈闭是进一步勘探的有利目标。  相似文献   

Systematic Geometric Image Measurement Errors of Circular Object Targets: Mathematical Formulation and Correction   总被引：2，自引：0，他引：2  

S. J. Ahn  H. J. Warnecke  & R. Kotowski 《The Photogrammetric Record》1999,16(93):485-502

The use of circular object targets is very common in spatial photogrammetric object reconstruction. An object circle is projected on to the image plane as an ellipse if the object plane and the image plane are not parallel to each other. The image co-ordinates of the centre of the ellipse are usually determined automatically by means of digital image processing. These co-ordinates are then used as observations for a subsequent reconstruction of the three dimensional object point. The image co-ordinates of the centre of the ellipse and the true co-ordinates of the projected centre of the circular object target are not identical; thus eccentricity is caused, resulting in systematic geometric image measurement errors. This paper describes the functional context of this eccentricity for a typical target/camera set-up. The possible solutions for a correction of this systematic eccentricity error are derived. Guidelines for the correct combination of object target sizes and exposure distances, guaranteeing reliable image point measurements and accurate object point determination, are proposed.  相似文献   

中国西部铂矿床类型与找矿方向探讨     

涂怀奎 《化工矿产地质》2004,26(4):220-227

中国铂矿资源严重不足,主要分布在中国西部,根据原生矿床特征可划分为4类：①硫化物型;②铬铁矿型;③辉石岩型;④层控型。寻找铂矿新类型和富铂(岩石)资源,应成为解决中国铂矿资源紧缺的重要任务。铂矿找矿方向：地台与地槽接合部位,特别是围绕着基性、超基性岩内外接触带,铂的预富集岩带与层控型铂矿带,另外还有砂铂型铂矿发育区有望扩大找铂前景。  相似文献   

The use of selected pseudo-invariant targets for the application of atmospheric correction in multi-temporal studies using satellite remotely sensed imagery     

D.G. Hadjimitsis  C.R.I. Clayton  A. Retalis 《International Journal of Applied Earth Observation and Geoinformation》2009

Because atmospheric effects can have a significant impact on the data obtained from multi-spectral satellite remote sensing, it is frequently necessary to make corrections before any other image processing can be started. This paper describes a robust and relatively simple atmospheric correction method that uses pseudo-invariant targets (PITs) in conjunction with the empirical line method. The method is based on the selection of a number of suitable generic PITs, on the basis that they are large, distinctive in shape, and occur in many geographical areas. Whereas the multi-temporal normalization method corrects all images to a selected reference image, in this method images are simultaneously corrected using targets with a range of estimated surface reflectance values. The paper describes some applications of the method for a range of environmental studies involving water quality and air pollution monitoring, and mapping land-cover changes.  相似文献   

环境工程地质质量多级模糊综合评判的基本思想与步骤     

张骏  杜东菊  彭建兵 《地球科学与环境学报》1991,(3)

环境工程地质质量综合评价是一个复杂的系统工程。影响质量评价的因素众多而又十分复杂,且各因素的影响程度也不相同,质量优劣的分级界线亦是模糊的。本文仅就采用多级模糊综合评判的方法,考虑多个因素的综合作用,对环境工程地质质量进行评价的基本思想途径与步骤方法,作一初步论述。此方法清晰、易用,能使更多影响质量评价的因素真实参与评判。这是一条环境工程地质质量评价由定性走向定量的有效途径,值得探索。  相似文献   

INCIDENTS OF TERRORISM IN THE UNITED STATES, 1997–2005     

Samuel Nunn 《Geographical review》2007,97(1):89-111

ABSTRACT. The geography of terrorism remains underexplored. By focusing on the spatial patterns of terrorist attacks, the settings and land uses in which attacks occur, and the methods used to perpetrate violence, this analysis helps build a theory of terrorism geography. Between 1 January 1997 and 11 September 2005, 178 terrorist incidents occurred in the United States. Analysis of these incidents suggests three insights. At the national scale, terrorism in the United States clustered in large urban areas, with regional differentiation of terrorist motives and targets. At the scale of individual attack sites, terrorist motivations pinpointed offices, clinics, and public spaces; right‐wing violence, military, government, and infrastructural targets; and religious terrorism, commercial and special land uses. At the scale of individual interactions, terrorists crossed paths with victims in various ways. For example, the 2001 anthrax‐attack letters and lone‐wolf terrorism created alternative intersections of perpetrators with victims.  相似文献