粤北302铀矿床同位素地球化学研究   总被引：11，自引：1，他引：10  

沈渭洲  凌洪飞  邓平  朱捌  黄国龙  谭正中 《铀矿地质》2010,26(2):80-87

位于粤北诸广山岩体东南部的302铀矿床是我国规模较大、埋藏较深的花岗岩型铀矿床之一。该矿床产于印支期油洞岩体和燕山早期长江岩体的断裂蚀变带内,矿区内NWW向基性岩脉十分发育,矿体呈似脉状、扁豆状或透镜状。同位素研究表明,矿石的沥青铀矿Sm-Nd和U-Pb等时线年龄（70 Ma）与油洞岩体（232 Ma）、长江岩体（160 Ma）的年龄相差巨大;主成矿期成矿流体的δDH2O值为-65‰～-82‰（平均为-75‰）,δ18OH2O值为6.8‰～0.6‰（平均为3.9‰）,反映出成矿流体主要由地幔流体组成;方解石的δ13C值为-8.4‰～-5.3‰,表明矿化剂ΣCO2也来自地幔;矿区内辉绿岩的（87Sr/86Sr）i值为0.70861～0.70882,花岗岩的（87Sr/86Sr）i值为0.73519～0.77152,萤石的（87Sr/86Sr）i值为0.71474～0.71697,表明成矿组分Sr可能来源于基性脉岩（幔源）与赋矿花岗岩体（壳源）,并呈不同程度的混合,而主成矿组分铀主要来源于赋矿花岗岩体。  相似文献   

粤北竹山下岩体锆石U-Pb同位素定年及其地球化学特征   总被引：1，自引：0，他引：1  

王联社  邓平  朱捌  沈渭洲  谭正中 《铀矿地质》2010,26(5):264-270

竹山下岩体锆石SHRI MP U-Pb年龄为161.0±3.0 Ma,属燕山早期岩浆活动产物。该岩体的主要元素显示富硅(Si O2=76.05%~79.16%)、富碱(K2O+Na2O=7.77%~8.40%)、强过铝质(A/CNK=1.08~1.26)和低CaO/Na2O值(0.04~0.06)等特征。微量元素富集大离子元素而亏损Ba,Sr,Ce和Ti;LREE轻微亏损(LREE/HREE=0.82~1.09),Eu亏损明显(δEu=0.06~0.11),且具有较明显的四分组效应(TE1,3=1.07~1.24)。上述特征表明,竹山下岩体属于典型的壳源型花岗岩,是在地壳伸展-减薄的构造背景下,由泥质变质岩经过低程度部分熔融的方式而形成。  相似文献   

Comparison of response of moss,lichens and attic dust to geology and atmospheric pollution from copper mine     

B. Balabanova  T. Stafilov  R. Šajn  K. Bačeva 《International Journal of Environmental Science and Technology》2014,11(2):517-528

Different sampling media (moss, lichen and attic dust) were used for monitoring the distribution of 15 elements, including certain trace elements, in the vicinity of an intensively exploited copper mine in the east of the Republic of Macedonia. Moss species (Hypnum cupressiforme and Campothecium lutescens), epiphytic lichens (Hypogymnia physodes and Evernia prunastri) and attic dust were collected for comparative analysis for monitoring air pollution. In both cases (lithological and anthropogenic affected areas) for the distribution of elements, the sampling media follows the expression capabilities: attic dust > moss > lichens. Enrichment factors M/L—moss vs. lichen, for plant response to elements distribution and D/L—attic dust vs. lichen, for historical response of elements distribution were significant for Cu and Ni, which were singled out as the main markers for anthropogenic and geogenic distribution. The factor analysis highlighted geogenic (F1: Ni-Cr-Cd-Fe-Al-K-Mn-Zn) and anthropogenic (F2: As-Cu-Pb) association of elements from three types of media samples. For anthropogenic affected areas, T value and F value for Cu content were significant at p < 0.05 and higher enrichment factors were obtained for lichen, moss and attic dust media (3.8, 5.0 and 5.7, respectively). Spatial distribution for element deposition (with emphasis on Cu and Ni) is not disturbed by the significant differences in the sampling media matrix. Treated sample materials (attic dust, moss, lichen) are shown to be useful in determining an anthropogenic impact, as well as the chemical properties or geological background on orographic diverse terrain in the presence of complex geological structure.  相似文献   

Responses of microorganisms and enzymes to soil contamination with metazachlor     

Ma?gorzata?Ba?magaEmail author  Jan?Kucharski  Jadwiga?Wyszkowska  Agata?Borowik  Monika?Tomkiel 《Environmental Earth Sciences》2014,72(7):2251-2262

A greenhouse pot experiment was conducted at the University of Warmia and Mazury in Olsztyn, with the aim of describing the influence of metazachlor on counts and biodiversity of soil microorganisms, soil enzymatic activity, physicochemical properties of soil and yield of spring oilseed rape. The first experimental factor was soil contamination with increasing rates of metazachlor: 0 (soil without the herbicide), 0.333 (recommended by the manufacturer), 6.666, 13.332, 26.665, 53.328, 106.656 and 213.312 mg kg^?1 dm of soil, while the second factor comprised two dates of determination: 30 and 60 days after starting the experiment. The tested herbicide had an adverse effect on reproduction of all analyzed microorganisms: oligotrophic bacteria and their endospore forms, Azotobacter spp. bacteria, organotrophic bacteria, actinomycetes and fungi. The values of the colony development and eco-physiological diversity indices decreased under the influence of excessive doses of the herbicide. Also, significant fluctuation in the enzymatic activity of soil was observed in response to the higher doses of metazachlor and depending on the date of determinations. The herbicide had an invariably negative influence on the activity of soil enzymes, causing the inhibition of dehydrogenases, catalase, urease, acid phosphatase, alkaline phosphatase, arylsulfatase and β-glucosidase. The physicochemical status of soil depended significantly on the degree of soil contamination with the herbicide, same as the yield of spring oilseed rape.  相似文献   

Economic benefit assessment of the geo-hazard monitoring and warning engineering system in the Three Gorges Reservoir area: a case study of the landslide in Zigui     

Yu  Shiwei  Hou  Jindong  Lv  Jun  Ba  Guizhi 《Natural Hazards》2014,75(2):219-231

The completion and operation of the Three Gorges Reservoir in China have increased the frequency of geo-hazards and dangers in the area. To monitor and to warn of geo-hazards effectively, the Chinese government has invested billions of funds for constructing a monitoring and warning engineering system. Similar to other social infrastructure investments, a reasonable assessment of investment returns is necessary. Therefore, this study proposes an economic benefit assessment model, which considers both the expected and the actual values. The economic benefit of the geo-hazard monitoring and warning engineering in the Three Gorges Reservoir areas is evaluated. Based on the engineering characteristics, the model reasonably defines the frontier of the input and output and adds the casualties and the losses of ecological environment into the economic benefit evaluation index system. A case study on the Zhangjiawan landslide in Guojiaba Town, Zigui County, was conducted. The evaluation results show that (1) land has the largest benefit in direct reductional loss (total of 56.7 %), while the largest indirect reductional losses of the hazard-bearing bodies are in agricultural production and ecological environment (total of 97.6 %); (2) the costs-to-expected return ratio of landslide monitoring and warning engineering is 1:280, whereas the cost-to-actual benefit ratio is 1:30; (3) the accumulation of relevant information and the public knowledge of geological disasters should be strengthened.

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Theory of Accretion onto Neutron Stars     

G. Alojandc  S. Kamara  M. Ba  F. Ulara 《Astrophysics》2004,47(4):513-518

Hydrodynamically stationary, spherically symmetric accretion onto a neutron star is examined taking the reverse effect of radiation into account. It is assumed that the plasma flow is adiabatic and that radiation is generated in a thin surface layer of the neutron star, where incoming particles are slowed down. It is shown that for stationary accretion, neither a stop, nor a substantial slowing down of the accretion flux is possible for any physically allowed conditions far from the neutron star.  相似文献   

基于动力学震源模型的三维沉积盆地直下型断层地震动模拟     

巴振宁  慕少聪  赵靖轩  梁建文 《震灾防御技术》2022,17(3):431-441

沉积盆地与近断层地震共同作用会增加地震破坏的风险水平,尤其是盆地下方直下型断层发震情况。采用动力学震源模型刻画断层破裂发震过程,开展沉积盆地直下型断层谱元法地震动模拟研究,探讨不同断层面初始剪应力和成核区位置下三维沉积盆地地表响应规律。研究结果表明,断层面应力降对盆地地表地震动的影响显著,在断层面强度一定的情况下,随着初始剪应力的增大,即应力降增大,盆地地表峰值响应增大,原因在于应力降的改变影响了断层破裂释放能量,进而引起断层破裂速度改变,最终导致盆地地表响应发生变化;改变断层面成核区位置会对盆地内部地震动分布规律产生影响,当成核区位置从断层中间向断层左侧移动时,盆地左侧地震动逐渐减小,而右侧地震动逐渐增大,最终表现为盆地右侧地震动显著高于盆地左侧,原因在于改变成核区位置后,导致近断层地震动的方向性效应发生变化。  相似文献   

Development and validation of a regional coupled atmosphere lake model for the Caspian Sea Basin     

Ufuk Utku Turuncoglu  Nellie Elguindi  Filippo Giorgi  Nicolas Fournier  Graziano Giuliani 《Climate Dynamics》2013,41(7-8):1731-1748

We present a validation analysis of a regional climate model coupled to a distributed one dimensional (1D) lake model for the Caspian Sea Basin. Two model grid spacings are tested, 50 and 20 km, the simulation period is 1989–2008 and the lateral boundary conditions are from the ERA-Interim reanalysis of observations. The model is validated against atmospheric as well as lake variables. The model performance in reproducing precipitation and temperature mean seasonal climatology, seasonal cycles and interannual variability is generally good, with the model results being mostly within the observational uncertainty range. The model appears to overestimate cloudiness and underestimate surface radiation, although a large observational uncertainty is found in these variables. The 1D distributed lake model (run at each grid point of the lake area) reproduces the observed lake-average sea surface temperature (SST), although differences compared to observations are found in the spatial structure of the SST, most likely as a result of the absence of 3 dimensional lake water circulations. The evolution of lake ice cover and near surface wind over the lake area is also reproduced by the model reasonably well. Improvements resulting from the increase of resolution from 50 to 20 km are most significant in the lake model. Overall the performance of the coupled regional climate—1D lake model system appears to be of sufficient quality for application to climate change scenario simulations over the Caspian Sea Basin.  相似文献   

Quantification of the urban heat island under a changing climate over Anatolian Peninsula     

Huseyin Ozdemir  Alper Unal  Tayfun Kindap  Ufuk Utku Turuncoglu  Zeynep Okay Durmusoglu  Maudood Khan  Mete Tayanc  Mehmet Karaca 《Theoretical and Applied Climatology》2012,108(1-2):31-38

The Anatolian Peninsula is located at the confluence of Europe, Asia, and Africa and houses 81 cities of which 79 of them have population over 100,000. We employed some criteria to select the cities from the 81 cities. After accomplishing all the criteria, eight cities were remaining for the study. Nonparametric Mann–Kendall test procedure was employed for the urban and rural stations of these cities to detect the long-term change in temperature trends. Statistical analysis of daily minimum temperatures for the period between 1965 and 2006 suggest that there is no statistically significant increase in rural areas. In contrast to the findings of the previous studies, however, all the urban sites and difference between urban and rural pairs show significant increase in temperatures, a strong indication for the existence of urban heat island (UHI) affect over the region. Regional Climate Model was also utilized to assess the changes in temperature by the end of century for the region. The findings suggest that an increase of up to 5°C is possible. Climate change effects enforced with UHI have the potential to cause serious problems for the entire region and hence needs to be studied thoroughly.  相似文献   

荒漠化,干旱与植被—以西非萨赫勒为例     

TucK.  CJ 张文哲 《气象科技》2000,28(2):41-46

关于西非荒漠化的本质和特征存在着许多看法。该文将追溯其历史，回顾荒漠化对气候影响的研究现状，并介绍一些有关研究结果。对荒漠化的认识通常为“沙漠”的扩张，是一个总体上不可逆转的人为过程。其过程与地表反照率增强，风沙加大以及土地生产力下降相联系。研究表明，在最近１６年里撒哈拉沙漠的边界和萨赫勒植被均变化不大，从植被水分有效利用率来看，“生产力”没有系统性降低，地表反照率也没有多少改变。自２０世纪５０年  相似文献