亚洲砂岩型铀矿区域分布规律和中国砂岩型铀矿找矿对策

20世纪80年代以来,继中亚（哈萨克斯坦,乌兹别克斯坦）早所发现大量砂岩型铀矿之后,俄罗斯,蒙古境内又找到了许多大型砂岩型铀矿床,至此,亚洲已成为世界上砂岩型铀资源的最集中产地,已发现的砂岩型铀矿床大体上沿着南北分别为塔木－华北陆地和西伯利亚陆块所围限,西起西西伯利亚低地,向南经哈,乌,再折向东经阿尔泰,萨彦,我国的青,甘,内蒙,直到大小兴安岭和鄂霍次克海的近东西走向,向南凸出的弧形构造带分布,俄罗斯将其命名为中央亚洲活动带,我国一些学称其为蒙古弧,此带内产出成因迥异,类型众多的大型,超大型金,多金属,块状硫化物,斑岩铜（金）矿以及火山岩型和砂岩型铀矿,带内如此丰富多彩的矿产资源与该带独特的地质构造演化密切相关,今后应大力加强对此构造带的地质研究和铀矿找矿。     

RESPONSE OF THE ATMOSPHERIC GENERAL CIRCULATION TO WINTER SNOW COVER ANOMALY*

In this paper,the response of the atmospheric general circulation to winter anomalous snow cover was investigated through observations studies and model simulation.Results from the observations show that:(1)the anomalous winter snow cover in the extratropics of Eurasian Continent bears an intimate relation to the contemporary atmospheric general circulation.The positive anomaly of winter snow cover is usually accompanied by positive atmospheric EUP teleconnection pattern and stronger East Asian winter monsoon:or vice versa.(2)The linkage between them suggests that the abnormal winter snow cover has an important impact on winter atmospheric general circulation.The anomalous snow cover pattern can lead to the anomaly of winter atmospheric EUP teleconnection pattern and thus influence East Asian Winter monsoon.With NCAR CCM2 including BATS land surface scheme,three groups of experiments were performed to examine the atmospheric response to the anomalous snow cover pattern and explore the relevant mechanism.Simulated results agree well with the observations,which testify the significant response of the atmosphere to snow cover anomaly.It is found that the radiative cooling induced by anomalous snow cover plays an important role in above processes,and the feedback of long-wave radiation can not be neglected.     

The sensitivity of numerical simulation of the east asian monsoon to different cumulus parameterization schemes

In this paper, a 5-level spectral AGCM is used to examine the sensitivity of simulated East Asian summer monsoon circulation and rainfall to cumulus parameterization schemes. From the simulated results of East Asian monsoon circulations and rainfalls during the summers of 1987 and 1995, it is shown that the Kuo’s convective parameterization scheme is more suitable for the numerical simulation of East Asian summer monsoon rainfall and circulation. This may be due to that the cumulus in the rainfall system is not strong in the East Asian monsoon region. This paper is supported by the National Key Progranmme “96-908”.     

Western Pacific in glacial cycles:Seasonality in marginal seas and variabilities of Warm Pool

A serics of low-latitude marginal seas, ranging from the southern South China Sea in the north to the Arafura Sea in the south, are located within the Western Pacific Warm Pool. As shown by rnicropaleontological, isotopical and organic geochemical analyses, the sea surface temperatures in the marginal seas at the last glacial maximum were much cooler than those in the open Western Pacific Ocean. The emergence of extensive shelves of the marginal seas at the glacial low sea-level stand and the decrease of surface temperatures in their deeper water parts resulted in a remarkable reduction of the ability of vapor and heat transport to the atmosphere, causing variabilities to the Warm Pool in the glacial cycles. The intensification of winter monsoon at the glacial stages not only led to a decrease of the surface water temperature and hence to an enhanced seasonality, but also carried moisture from the sea to the tropical islands, giving rise to the downward shift of snowline and mountainous vegetation zones there. It may offer a new alternative in solution of the “Tropical Ocean Paleo-temperature Enigma”. Project supported by the National Natural Science Foundation of China (Grant No. 49576286).     

Transition from mildly-tholeiitic to calc-alkaline suite: the case of Chichontepec volcanic centre, El Salvador, Central America

The Chichontepec volcano is a Plio-Pleistocene composite volcano that erupted lavas ranging from high-alumina basalts to dacites. It experienced a caldera-forming paroxysmal eruption during the early Pleistocene. Pre-caldera lavas are mildly tholeiitic and they evolved mainly by low pressure crystal fractionation, notwithstanding the fact that most mafic lavas (low-MgO high-alumina basalts) retain traces of polybaric evolution. Conversely, post-caldera lavas, which are mainly pyroxene andesites, are clearly calc-alkaline, having evolved by open-system crystal fractionation. Sr–Nd isotopic data and trace elements characteristics indicate that the same mantle source was involved in the petrogenesis of these series. Modelling the AFC process showed that it did not play any role in the petrogenesis of these rocks; a crystal fractionation model is considered to be more relevant. A slight variation in the fractionating assemblage could have caused the transition from an early mildly tholeiitic trend to a late calc-alkaline one. Mineralogical evidence, mass-balance calculations and elemental chemistry support this hypothesis, assuming that the greater amount of pyroxene on the liquidus is at the expense of plagioclase; this would have prevented the trend in iron enrichment.     

Rural settlements in transition – agricultural and countryside crisis in the Central-Eastern Europe

The paper presents a synthesis of French and Bulgarian researches on the transition in villages in Central Eastern Europe. The main points focus on three questions, the rural unemployment and the crisis of small towns, the demographical deterioration, the new relations between villages and towns. A generalization of the rural central places' visual change and metaphors is proposed, completed by a typology of rural settlements. The question of the rural administrative divisions is discussed, with its implication for the future. As a whole the paper gives a contribution to the problematic of the likely development in the rural evolution pattern throughout Europe. This revised version was published online in July 2006 with corrections to the Cover Date.     

Regional Environmental Differentiation in China Sincethe Mid-Pleistocene Inferred from Lake Recordsand Its Relation with East Asian Monsoons

Comparative study of long lake records in different regions in China can provide some significant information about the regional differentiation of the environment and Asian monsoon activities. However, intensively studied lacustrine cores with a span of a few hundred thousand years are very rare in China. The available examples are only three long cores from the Zoige basin in the eastern Qinghai-Tibet plateau, the Qaidam basin in the northern Qinghai-Tibet plateau and the Dianchi basin in the Yunnan plateau respectively. The results show that the regional environmental differentiation since the Mid-Pleistocene involved three stages, i.e. 780-480, 480-160, 160-0 ka B.P. In each of the three stages different regions of China had their own distinctive environmental characteristics, indicating that the uplift of the Qinghai-Tibet plateau played a major role in the environmental differentiation process.     

Eastern Asian hydrometeorology simulation using the Regional Climate System Model

We present the hydrometeorology of eastern Asia during April 1995 simulated by the Regional Climate System Model. The amount and location of simulated monthly precipitation agrees well with observations. Soil water content variation was closely correlated with precipitation. Land-surface evaporation and the surface energy budget were strongly controlled by soil moisture content. A sensitivity test with reduced initial soil moisture content suggested that near-surface soil moisture spins up quickly after heavy precipitation events. However, variations in the initial soil moisture field may alter details of the simulated precipitation which can introduce further complexity in climate simulations.     

广东沿海经济高速发展区人地系统可持续发展研究

粤中沿海经济高速发展的典型区域－深圳市人地中系统持续性从１９８０￣１９９０年逐渐增加,但１９９１年开始下降;东莞市人地系统可持续性从１９８０年以后逐渐增强。目前深圳市和东莞市人地系统均处于弱可持续性状况。     

沈阳的郊区化—兼论中西方郊区化的比较

在我国８０年代才开始郊区化过程，研究刚刚起步。亟待城市学界对我国郊区化的特点、机制、发展规律以及与西方的异同进行深入研究，发掘它对城市发展有利的一面，本文正是出于这目的，研究了沈阳的郊区，内容包括地域划分，８０年代是否开始、大体的强度，９０年代的 状况，机制分析和调控建议。