基于Pléiades立体影像数字正射影像精度研究

基于Pléiades 1B立体全色影像,采用PCI Geomatic软件进行空三加密,利用RPC有理函数模型和不同像控点进行平差解算,对DOM平面精度和左右像片接边精度进行统计和分析,为后期利用Pléiades立体影像进行1∶10000 DOM生产提供参考。     

天山乌鲁木齐河源1号冰川消融对气候变化的响应

Current glacier recession under the global warming has aroused world-wide attention.Initiated from 1958,the observations show that over the past 50 years,the glacier has changed remarkably in the aspects of snow-firn stratigraphy,ice formation zone,ice temperature,area and terminus position,etc.These changes are apparently the results of temperature rise in this area.The glacier recession continued throughout the entire observed time period,and showed an accelerated tendency since 1985.Meltwater runoff also increased 84.2% over the last 20 years.     

R?le du brassage et du stockage magmatique dans l’homogénéisation des granito?des calco-alcalins: Cas du pluton composite de Za?r (Maroc central)

Resume.  Le pluton calco-alcalin de Za?r est composé de trois principaux faciès pétrographiques répartis en deux unités granitiques imbriquées. Ces faciès, de différents degrés d’hybridation et de différenciation, résultent de mélanges magmatiques entre des magmas basiques mantelliques de type ?HAB? (basalte hyperalumineux) et un magma anatectique issu de la fusion partielle de matériaux crustaux (métapélites ou métagrauwackes). La répartition des faciès granitiques de Za?r peut s’expliquer selon un modèle pétrogénétique de type ?MASH? (melting-assimilation-storage-homogenization) où des magmas hybrides seraient formés suivant différentes proportions de mélanges magmatiques acide-basique. Ces magmas auraient subides conditions d’ascension spécifiques et seraient mis en place sous forme de 3 grandes injections successives:

A statistical study of the upstream intermediate ion boundary in the Earth’s foreshock

A statistical investigation of the location of onset of intermediate and gyrating ion populations in the Earths foreshock is presented based on Fixed Voltage Analyzer data from ISEE 1. This study reveals the existence of a spatial boundary for intermediate and gyrating ion populations that coincides with the reported ULF wave boundary. This boundary position in the Earths foreshock depends strongly upon the magnetic cone angle _BX and appears well defined for relatively large cone angles, though not for small cone angles. As reported in a previous study of the ULF wave boundary, the position of the intermediate-gyrating ion boundary is not compatible with a fixed growth rate of the waves resulting from the interaction between a uniform beam and the ambient plasma. The present work examines the momentum associated with protons which travel along this boundary, and we show that the variation of the boundary position (or equivalently, the associated particle momentum) with the cone angle is related to classical acceleration mechanisms at the bow shock surface. The same functional behavior as a function of the cone angle is obtained for the momentum predicted by an acceleration model and for the particle momentum associated with the boundary. However, the model predicts systematically larger values of the momentum than the observation related values by a constant amount; we suggest that this difference may be due to some momentum exchange between the incident solar-wind population and the backstreaming particles through a wave-particle interaction resulting from a beam plasma instability.     

Stochastic models for simulation of strong ground motion in Iceland

Two types of modelling approaches for simulating ground motion in Iceland are studied and compared. The first type of models, named discrete‐time series models (ARMA), are based solely on measured acceleration in earthquakes occurring in Iceland. The second type of models are based on a theoretical seismic source model called the extended Brune model. Based on measured acceleration in Iceland during the period 1986–1996, the parameters for the extended Brune models have been estimated. The seismic source models are presented here as ARMA models, which simplifies the simulation process. A single‐layer soil amplification model is used in conjunction with the extended Brune model to estimate local site amplification. Emphasis is put on the ground motion models representing the variability in the measured earthquakes, with respect to energy, duration and frequency content. Demonstration is made using these models for constructing linear and non‐linear probabilistic response spectra using a discretised version of the Bouc–Wen model for the hysteresis of the second‐order system. Copyright © 2001 John Wiley & Sons, Ltd.     

西昆仑麻扎构造混杂岩带中－下侏罗统叶尔羌群源区构造背景分析

本文在收集和总结前人研究成果的基础上,通过对西昆仑麻扎地区中-下侏罗统叶尔羌群碎屑组分和砂岩地球化学特征分析,讨论了叶尔羌群沉积源区大地构造背景.在莎里塔什组沉积时期,物源区的构造背景主要为大陆岛弧、大洋岛弧的性质;杨叶组沉积时期,源区的大地构造背景为大陆岛弧,兼有活动大陆边缘性质;塔尔尕组沉积时期,源区构造背景复杂:既显示活动大陆边缘和岛弧(大洋岛弧、大陆岛弧)的性质,同时还显示出被动陆缘环境,其可能与晚三叠世造山开始时克拉通地块边缘的卷入有关.     

三江并流带环境地质与基础设施建设对策浅析

三江并流带位于印度板块与欧亚板块的缝合线部位，新构造运动强烈，构造发育，岩石破碎，地势陡峻，地质环境异常脆弱，地震、滑坡、崩塌、泥石流等地质灾害频繁。区内旅游资源、生物资源、水利资源、矿产资源、人资源极为丰富，是西部大开发中极有前景的地域，亟需加强基础设施建设。为了保护三江并流带的自然环境、生态环境、地质环境，在公路、水电等基础设施的建设中，应该采取开发与保护并重的对策。本针对该区新构造运动发育、岩石强烈破碎的特点，分析在公路、水电等基础设施建设中给区域环境地质带来的不良影响，并提出处治措施与对策建议。     

甘肃大型变形构造及蛇绿构造混杂岩带特征

大型变形构造带是地球表层重要的构造现象,它们记载了地壳的构造变形（走滑错移、逆冲叠覆和伸展滑移）过程及其动力学机制。本文根据大型变形构造定义及其分类原则,将甘肃省大型变形构造划分为3大类10种类型,初步厘定出大型变形构造带23个,简要叙述了主要大型变形构造规模、产状、构造层次、物质组成、变形期次等基本特征,探讨了大型变形构造与蛇绿构造混杂岩带的关系,从全省北山造山带、祁连造山带、西秦岭造山带和鄂尔多斯盆地“三带一盆”的构造格局出发,探讨大型变形构造形成、演化历史。     

Can unstable relics save pure Cold Dark Matter?

The standard CDM model fails to describe the power spectrum of fluctuations since it gives too much power at small scales. Among other possible improvements, it has been suggested that an agreement with observations can be achieved with the addition of a late decaying particle, through the injection of nonthermal radiation and the consequent increase of the horizon length at the equivalence time. We analyze the possibility of implementing this idea in some extensions of the electroweak standard model, discussing the cosmological and astrophysical bounds to which these schemes are subject.     

Inferred ultrahigh-temperature metamorphism of amphibolitized olivine granulite from the Sør Rondane Mountains, East Antarctica

This paper reports the first evidence of ultrahigh-temperature (UHT) metamorphism from the Sør Rondane Mountains, eastern Dronning Maud Land, East Antarctica, which is evident as orthopyroxene + spinel symplectite in an amphibolitized mafic granulite. The granulite consists of olivine, orthopyroxene, clinopyroxene, pargasitic amphibole, plagioclase, and ilmenite, and it possesses a within-plate alkali basalt signature. The local bulk chemical composition of symplectite, major and trace element compositions, and thermodynamic calculations for the symplectite, suggest the presence of garnet at the high-pressure stage and that the symplectite formed from garnet, olivine, and primary orthopyroxene by decompression from more than 12 kbar at 1000 °C. The granulite records a subsequent amphibolite-facies overprint (<700 °C at <6 kbar) that involved the chemical re-equilibration of several phases. The obtained pressure–temperature (P–T) conditions and P–T path are different from the UHT metamorphism from the Schirmacher Hills, central Dronning Maud Land, which is considered to have occurred in a back-arc tectonic setting. The relatively high-P conditions and the decompression path reconstructed in the present study are similar to those reported for southern India, Sri Lanka, and part of northeastern Mozambique, possibly reflecting continental thickening and exhumation during the main collision event between East and West Gondwana.