中国明矾石资源及其应用   总被引：7，自引：0，他引：7  

宣之强 《化工矿产地质》1998,20(4):279-286

中国明矾石矿资源丰富。矿床多产于滨西太平洋造山活化构造带中,属陆相火山岩系中的“热水沉积”矿床,可划分为中低温型及高中温型两种类型。残余岩浆水与大气水混合的热水交代火山岩是重要的成矿机制。我国东南沿海及宁芜 庐枞地区为明矾石的有利找矿远景区。明矾石矿产品之中除明矾外,其深度加工及废料再加工产品均具较高的利用价值,综合利用前景广阔。  相似文献   

On the use of biorthogonalization for solving systems of linear equations in numerical weather forecasting     

Michal Baťka  Reviewer K. Segeth 《Studia Geophysica et Geodaetica》1979,23(3):275-287

Summary The paper deals with the solving of large systems of linear equations which are created when implicit and semi-implicit differential methods are used to solve the primitive equations of the atmosphere. Systems with similar properties are also created in solving boundary problems of multi-level filtered models. First, the specific properties of these systems, which are then used to construct an efficient method of solving them, are described.  相似文献   

Outline of the Pan-African geology of adrar des Iforas (Republic of Mali)     

R. Black  H. Ba  E. Ball  J. M. Bertrand  A. M. Boullier  R. Caby  I. Davison  J. Fabre  M. Leblanc  L. I. Wright 《International Journal of Earth Sciences》1979,68(2):543-564

The Iforas (60 000 km²) falls within the Pan-African mobile belt bordering the West-African craton in north-eastern Mali Republic. It is characterized by major N-S shear belts parallel to the edge of the craton which delimit longitudinal blocks some of which have undergone considerable horizontal displacements. The central core of the Iforas which consists largely of reactivated pre-Pan-African basement injected by Pan-African syn- and post-tectonic intermediate and acid plutonic rocks, has behaved as a relatively rigid blocks during the Pan-African dividing the orogenic belt into a western Iforas and an eastern Iforas.Western Iforas displays W to E zonation: an ophiolitic suture (Timetrine); trench volcano-sedimentary deposits cut by gabbros diorites and acid granitoids (Tilemsi); and a late orogenic composite »coastal range batholith intruding the pre-Pan-African basement of Central Iforas and its overlying volcano-sedimentary deposits which here display a littoral facies and a tillite.Central Iforas consists of two major units: a polycyclic pre-Pan-African basement metamorphosed under high amphibolite facies conditions of presumed Eburnean age and the Iforas granulite block bound to the W, N and E by shear zones.Eastern Iforas was totally separated during metamorphism and deformation from the Iforas granulite block. From West to East, three lithological assemblages have been recognised separed by shear belts: a Quartzite Group, a Gneissic Group and a Pelitic Group the latter representing the southern prolongation of the central Hoggar Pharusian province.Shear zones are an essential feature of Pan-African tectonism East of the West-African craton. The superimposed stress fields have been recognised producing: early N20° trending sinistral shear zones, a north-south dextral shear zone (Andjour-Tamaradant shear zone) and late conjugating sinistral NNW and dextral ENE wrench faults.Late Pan-African events reflect the uplift and unroofing of the Pan-African composite batholith, the intrusion of circular granite plutons often located close to shear zones and alternating episodes of distension and compression.Lastly the simple model proposed for the closing stages of the Pan-African in the Iforas is that of an active continental plate margin separated from the West African craton by an oceanic domain. Subsequent continental collision to the South with a promotory of the West African craton led to the formation of the Dahomeyan thrust front and modified the stress field. Closure of the oceanic domain of western Iforas is thought to have taken place by continued eastward subduction of the oceanic plate and sinistral movement along an inferred north westerly trending transform fault coinciding with the future Cretaceous Gao trough and an alignement of strong positive gravity anomalies. It was accompanied by the northerly migration of central and western Iforas along the conjugating dextral N-S Andjour-Tamaradant shear zone. Further shortening led to folding of the arcuate Timetrine-Ydouban-Gourma fold belt overlying the deformed margin of the West African craton.

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Zusammenfassung Das Iforas-Gebiet (60 000 km²) gehört zur pan-afrikanischen Bewegungszone, die in Mali an das westafrikanische Kraton grenzt. Diese Zone wird von N-S Scherbewegungen parallel zum Kraton durchzogen, wobei größere horizontale Versetzungsbeträge langgestreckte Blöcke herausgetrennt haben. Der zentrale Teil von Iforas besteht im wesentlichen aus reaktiviertem prae-panafrikanischem Basement, das in pan-afrikanischer Zeit von syn- und posttektonischen, intermediären und sauren Plutoniten intrudiert wurde. Dieses Gebiet wirkt als relativ starrer Block, der während der pan-afrikanischen Orogenese den Orogengürtel in einen westlichen und einen östlichen Ast teilt. Das westliche Iforas-Gebiet zeigt eine E-W Zonierung: eine Ophiolith-Sutur, einen vulkano-sedimentären Gürtel und einen Rand-Batholithen.Zentral-Iforas wird aus zwei Einheiten aufgebaut: ein mehrfach metamorphisiertes Basement und einen Granitblock.In den überregionalen Scherzonen lassen sich drei Stress-Felder erkennen: eine ältere 20° streichende sinistrale Scherzone, eine N-S dextrale Scherzone und jüngere NNW und dextrale ENE Bruchzonen.Spät-pan-afrikanische Ereignisse sind durch Heraushebung und Abtrag, Granitintrusionen und wechselnden Dehnungs- und Kompressionsbewegungen gekennzeichnet.

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Résumé L'Adrar des Iforas (60 000 km²) fait partie de la zone mobile pan-africaine en marge du craton ouest-africain au Nord-Est de la République du Mali. La région est caractérisée par d'importants accidents mylonitiques parallèles à la bordure du craton qui délimitent des compartiments longitudinaux dont certains ont subi des déplacements horizontaux considérables. La zone dorsale des Iforas qui consiste essentiellement en un socle pré-pan-africain réactivé et injecté au Pan-Africain par des roches plutoniques intermédiaires et acides, syn- et post-tectoniques, s'est comportée en compartiments relativement rigides au cours du Pan-Africain, divisant la chaîne en un rameau occidental et un rameau oriental.Le rameau occidental présente une zonation d'Ouest en Est: une suture ophiolitique (Timetrine); des dépôts volcano-sédimentaires de fosse recoupés par des gabbros et des diorites; et un vaste batholite composite tardi-orogénique qui recoupe le socle pré-pan-africain de la zone dorsale des Iforas et sa couverture de dépôts volcanosédimentaires ici à faciès littoral.La zone dorsale des Iforas comprend deux unités majeures: un socle prépan-africain polycyclique métamorphisé dans le faciès amphibolite, d'âge éburnéen présumé et le môle granulitique des Iforas, délimité à l'W, au N et à l'E par des accidents mylonitiques.Le rameau oriental était séparé du môle granulitique des Iforas lors du métamorphisme et de la déformation. D'W en E, on trouve trois unités séparées par des zones mylonitiques: un Groupe de Quartzites, un Groupe de Gneiss et un Groupe de Pélites. Ce dernier représente le prolongement vers le Sud de la province pharusienne du centre Hoggar.Les grands accidents de cisaillement sont un fait marquant du tectonisme pan-africain à l'Est du craton ouest-africain. Trois champs de contraintes superposées ont produit des accidents précoces sénestres de direction N20, un accident N-S dextre (Andjour-Tamaradant), et des failles cisaillantes tardives conjuguées d'orientation NNW sénestres et ENE dextres.Les événements pan-africains tardifs sont marqués par la surrection et l'érosion des batholites pan-africains, la mise en place de plutons granitiques souvent à proximité des grands accidents et par des alternances de distensions et de compressions.Enfin un modèle simple est proposé pour les stades ultimes du Pan-Africain dans l'Adrar des Iforas: une marge continentale active séparée du craton ouest-africain par un domaine océanique; suite à une collision au Sud avec un promontoire du craton ouestafricain qui aurait produit le front de chevauchement dahomeyen et modifié le champ de contraintes, la fermeture du domaine océanique de l'Ouest Iforas se serait produite par subduction à l'E de la plaque océanique et une translation sénestre le long d'une faille transformante orientée NW et coincidant avec le fossé crétacé de Gao et un alignement d'anomalies gravimétriques positives. Elle aurait été accompagnée par le déplacement vers le N de l'Iforas occidental et central le long de l'accident cisaillant dextre d'Andjour-Tamaradant. Cette fermeture aurait provoqué les plissements de la chaîne du Timetrine-Ydouban-Gourma qui repose sur la bordure déformée du craton ouestafricain.

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A modelling of effects of variable saturation in invaded zone near borehole on neutron tool response in the gas-bearing Miocene formations of the Carpathian foredeep,Poland     

M. Bała  U. Woźnicka  T. Zorski  A. Drabina 《Journal of Applied Geophysics》2011,73(1):84-91

Invasion of mud filtrate from the borehole into the surrounding formation can significantly alter the response of logging tools.In this paper the neutron tool response was calculated for a gas-bearing rock crossed by the borehole.The invaded zone is characterized by variable fluid and gas saturation and is defined by a specific hyperbolic function. The saturation function is based on the characteristics of Polish Carpathian Foredeep Miocene formations reached in gas-bearing rocks. The whole system including neutron tool equipped with Am-Be neutron source and a set of neutron detectors, borehole, invaded zone, and virgin zone, was numerically modeled and used as the input to the Monte-Carlo neutron transport code. The response of each detector was calculated for different combinations of porosity and saturation of invaded zone and virgin zone.  相似文献   

Small-scale marine fisheries policy in Vietnam   总被引：1，自引：0，他引：1  

Robert Pomeroy  Kim Anh Thi Nguyen  Ha Xuan Thong 《Marine Policy》2009

Vietnam's marine fisheries are considered to be small scale and are concentrated in coastal near-shore waters. This has resulted in heavy pressure on near-shore fisheries resources. Near-shore fisheries are considered by fishers and the government to be over-exploited, causing hardship for many coastal communities. This paper reviews and analyzes changes in policy towards small-scale fisheries in Vietnam over the last two decades. The primary issues facing the small-scale fisheries in Vietnam are to restructure the near-shore fisheries and to address over-capacity. Recommended actions include improved fisheries statistics, resources for provincial fisheries staff, and a coordinated and integrated approach involving a mixed strategy of resource management; resource restoration; economic and community development; and new governance arrangements.  相似文献   

Multivariate analysis of fluorescence and source identification of dissolved organic matter in Jiaozhou Bay, China   总被引：1，自引：0，他引：1  

JIANG Fenghu  YANG Baijuan  LEE Frank Sen-Chun  WANG Xiaoru  CAO Xuan 《海洋学报(英文版)》2009,28(2):60-72

Hierarchical clustering analysis and principal component analysis (PCA) methods were used to assess the similarities and dissimilarities of the entire Excitation-emission matrix spectroscopy (EEMs) data sets of samples collected from Jiaozhou Bay, China. The results demonstrate that multivariate analysis facilitates the complex data treatment and spectral sorting processes, and also enhances the probability to reveal otherwise hidden information concerning the chemical characteristics of the dissolved organic matter (DOM). The distribution of different water samples as revealed by multivariate results has been used to track the movement of DOM material in the study area, and the interpretation is supported by the results obtained from the numerical simulation model of substance tracing technique, which show that the substance discharged by Haibo River can be distributed in Jiaozhou Bay.  相似文献   

Exploring spatial-temporal change and gravity center movement of construction land in the Chang-Zhu-Tan urban agglomeration   总被引：1，自引：0，他引：1  

Li  Zhuo  Jiang  Weiguo  Wang  Wenjie  Lei  Xuan  Deng  Yue 《地理学报(英文版)》2019,29(8):1363-1380

Urban agglomeration is caused by the continuous acceleration of the urbanization process in China. Studying the expansion of construction land can not only know the changes and development of urban agglomeration in time, but also obtain the great significance of the future management. In this study, taking Changsha-Zhuzhou-Xiangtan (Chang-Zhu-Tan) urban agglomeration in Hunan province as a study area, Landsat images from 1995 to 2014 and Autologistic-CLUE-S model simulation data were used. Moreover, several factors including gravity center, direction, distance and landscape index were considered in the analysis of the expansion. The results revealed that the construction area increased by 132.18%, from 372.28 km² in 1995 to 864.37 km² in 2014. And it might even reach 1327.23 km² in 2023. Before 2014, three cities had their own respective and discrete development directions. However, because of the integration policy implementation in 2008, the Chang-Zhu-Tan began to gather, the gravity center moved southward after 2014, and the distance between cities decreased, which was in line with the development plan of urban expansion. The research methods and results were relatively reliable, and these results could provide some reference for the future land use planning and spatial allocation in the urbanization process of Chang-Zhu-Tan urban agglomeration.

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玄松柏  邢乐林  何志堂  张世伟  李辉 《大地测量与地球动力学》2008,28(4):72-74

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Effect of open gap in coastal forest on tsunami run-up—investigations by experiment and numerical simulation     

Nguyen Ba Thuy  Katsutoshi Tanimoto  Norio Tanaka  Kenji Harada  Kosuke Iimura 《Ocean Engineering》2009,36(15-16):1258-1269

The objective of this study is to investigate the effects of an open gap, such as a road, in a coastal forest on tsunami run-up. A numerical model based on two-dimensional nonlinear long-wave equations was developed to account for the effects of drag and turbulence induced shear forces due to the presence of vegetation. Experiments were conducted on a forest simulated with vertical cylinders by changing the gap width. The numerical model was validated in good agreement with the experimental results. The numerical model was then applied to a wide forest of Pandanus odoratissimus, a tree species that is a dominant coastal vegetation on a sand dune in South and Southeast Asia. The effect of vertical stand characteristics of P. odoratissimus with aerial roots was considered on the drag resistance. A straight open gap perpendicular to the shoreline was used to investigate the effect of gap width. As the gap width increases, the flow velocity at the end of the open gap first increases, reaches a maximum, and then decreases, while the run-up height increases monotonously. The maximum velocity in the present condition is 1.7 times the maximum velocity without a coastal forest. The effects of different gap arrangements in the forest on tsunami run-up were also investigated in this paper. The flow velocity at the end of an open gap can be reduced by a staggered arrangement.  相似文献   

寻路地图设计中相关问题研究   总被引：1，自引：0，他引：1  

刘芳  王光霞  侯璇  张威巍  胡香 《测绘科学技术学报》2009,26(4)

以郑州市街头的寻路地图为例,对其设计现状进行了分析,指出了这些地图的特点和其在设计上存在的不足之处.根据寻路地图的目的和用户的特殊性,制作了寻路地图样图,并就其在定向和路线选择等方面进行了试验,对实验结果进行了分析和研究.结果表明地图内容、参考方向和地图符号是影响用户定向和路线选择的主要因素.以此为基础,得出了寻路地图设计中应当遵循的一些规律.  相似文献