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841.
An integrated approach was performed on the soil,plant-crops and groundwater system at the Thiva basin,to evaluate the extent and intensity of the heavy metal contamination,the percentage of metals tra...  相似文献   
842.
The Bayankhongor ophiolite zone, a NW-SE strik-ing linear structure 400 km long and up to 25 km wide, is the largest ophiolite association in Central Mongolia and possibly in all of Central Asia. The Bayankhongor cop-per mineralization was investigated by us in connection with detailed research of the ophiolite complexes in 1997-2011. With regard to their origin the ore formations belong to genetic type of gold-bearing massive sulphide deposit with magmatic seat of the island arc.  相似文献   
843.
We study the transition from regular to chaotic motion in a prolate elliptical galaxy dynamical model with a bulge and a dense nucleus.Our numerical investigation shows that stars with angular momentum Lz less than or equal to a critical value Lzc,moving near the galactic plane,are scattered to higher z,when reaching the central region of the galaxy,thus displaying chaotic motion.An inverse square law relationship was found to exist between the radius of the bulge and the critical value Lzc of the angular m...  相似文献   
844.
通过喷涂胶结内衬的方法对埋于皇后大学地球工程实验室西侧试验坑的两根直径1.2m且底部(invert)被强烈腐蚀的金属管道进行了修复。在金属管道以及内部的衬板均装置有线性电位器(1inear poten-tiometers),传统应变传感器以及光纤应变传感器用于测量管道直径的变化。并分别在1.2m与2.1m的埋深下利用标准单轴和平衡悬架轴加载的方法对管道在工作荷载下的性能做了评估。之后在1.2m埋深下利用平衡悬架轴加载对管道的最大极限状态进行了测试。将管道从地底挖掘出后,观测了修复后的厚度剖面。本文简要说明了本次修复对管道在工作载荷下的变形与曲率产生的影响。之后对最大极限状态(包括裂纹的分布和抗表面载荷能力)进行了描述。本次试验所得结论已考虑加载过程中圆周弯矩和内衬裂纹的影响。  相似文献   
845.
The AravallieDelhi and Satpura Mobile Belts(ADMB and SMB)and the Eastern Ghat Mobile Belt(EGMB)in India form major Proterozoic mobile belts with adjoining cratons and contemporary basins.The most convincing features of the ADMB and the SMB have been the crustal layers dipping from both sides in opposite directions,crustal thickening(w45 km)and high density and high conductivity rocks in upper/lower crust associated with faults/thrusts.These observations indicate convergence while domal type refectors in the lower crust suggest an extensional rifting phase.In case of the SMB,even the remnant of the subducting slab characterized by high conductive and low density slab in lithospheric mantle up to w120 km across the PurnaeGodavari river faults has been traced which may be caused by fuids due to metamorphism.Subduction related intrusives of the SMB south of it and the ADMB west of it suggest NeS and EeW directed convergence and subduction during MesoeNeoproterozoic convergence.The simultaneous EeW convergence between the Bundelkhand craton and Marwar craton(Western Rajasthan)across the ADMB and the NeS convergence between the Bundelkhand craton and the Bhandara and Dharwar cratons across the SMB suggest that the forces of convergence might have been in a NEeSW direction with EeW and NeS components in the two cases,respectively.This explains the arcuate shaped collision zone of the ADMB and the SMB which are connected in their western part.The Eastern Ghat Mobile Belt(EGMB)also shows signatures of E eW directed MesoeNeoproterozoic convergence with East Antarctica similar to ADMB in north India.Foreland basins such as Vindhyan(ADMBeSMB),and Kurnool(EGMB)Supergroups of rocks were formed during this convergence.Older rocks such as Aravalli(ADMB),MahakoshaleBijawar(SMB),and Cuddapah(EGMB)Supergroups of rocks with several basic/ultrabasic intrusives along these mobile belts,plausibly formed during an earlier episode of rifting during PaleoeMesoproterozoic period.They are highly disturbed and deformed due to subsequent MesoeNeoproterozoic convergence.As these Paleoproterozoic basins are characterized by large scale basic/ultrabasic intrusives that are considerably wide spread,it is suggested that a plume/superplume might have existed under the Indian cratons at that time which was responsible for the breakup of these cratons.Further,the presence of older intrusives in these mobile belts suggests that there might have been some form of convergence also during Paleoproterozoic period.  相似文献   
846.
<正>In the present study,we present the occurrence and emplacement of chromite ore deposits from two abandoned mines(Kankavali[Janoli]and Wagda) in the Sindhudurg district of Maharashtra,India.These ores,that occurred as lenses and are associated with metamorphic and ultrabasic rocks,consist of octahedral grains of chromite,while clinochlore is present between the interstices of these grains.The Kankavali(Janoli) and Wagda ores revealed a dominance of Cr_2O_3 followed by FeO and variable proportions of A1_2O_3,MgO,and SiO_2.The former deposits have a slightly higher Cr_2O_3(average 52 wt%) and FeO(~18 wt%) than those from Wagda(Cr_2O_3~50 wt%,FeO~25 wt%).The similar Cr~# values(0.73 for Kankavali[Janoli],0.74 for Wagda) correspond to those reported for typical podiform-type chromite deposits.We suggest that the ores were emplaced as phacoliths in folded outcrops with a steep easterly dip and a northwest-southeast trend.We postulate the continuation of the fold structure from Janoli to Wagda(~4.5 km apart) and the probable (sporadic) occurrence of chromite along this stretch.The possibility of the contribution of chromite grains from these areas to the coastal placer deposits cannot be ruled out.  相似文献   
847.
UCODE反演程序的原理及应用   总被引:2,自引:0,他引:2       下载免费PDF全文
夏强  万力  王旭升  E.Poeter 《地学前缘》2010,17(6):147-151
对地下水模型进行反演是模拟过程中的一个必要步骤,使用反演程序自动校正模型可快速确定最佳拟合的参数值,分析参数对模拟结果的敏感性,比人工试算-调整法更为优越。UCODE是一款被广泛应用的地下水模型反演程序,它使用高斯牛顿法进行参数优化,反演结果对参数初值有一定的依赖性。通过建立假想的非稳定流模型,进行6组数值试验,验证了UCODE程序的实用性。尽管参数的初始取值会影响反演的进程,但只要取值适当,UCODE就能实现优化参数的目的。  相似文献   
848.
含水层的一种普遍规律:渗透系数随深度衰减   总被引:5,自引:0,他引:5  
国内外多个含水层的研究都发现渗透系数具有随深度衰减的规律。给出了多孔介质和裂隙介质中渗透系数随深度衰减的一般模型及简化模型,并用该简化模型分析了多个含水层的渗透系数随深度衰减的规律。研究发现,随着渗透系数测试深度的增大,衰减系数明显变小;渗透系数测试深度相近的含水层,岩性对衰减系数有一定程度影响。渗透系数随深度衰减的规律应该在地下水科学的相关研究中引起重视。  相似文献   
849.
Seawater samples collected at three depths from 68 stations along the Northern Spanish coast were analysed for dissolved/dispersed petroleum aromatic hydrocarbons by UV-fluorescence and for 25 individual compounds by GC-MS. Sampling was performed in December 2002, just after the Prestige oil spill, and in February-March and September 2003. Higher concentrations of total aromatic hydrocarbons were found at all depths in the samples collected during December 2002 off the Galicia coast, with levels ranging between 0.19 and 28.8 microg/L eq. oil (0.1-4.8 microg/L chrysene eq.). These values decreased in the following cruises, till <0.05-2.86 microg/L oil eq. (av. 0.23 microg/L chrysene eq.) in September 2003, possibly representing the background levels for the region. However, in the Cantabrian coast they were still high at the surface in the March cruise, probably by the late arrival of the fuel-oil to this area. Some coastal hot spots were also identified, with values up to 29.2 microg/L fuel-oil eq., close to river mouths and urban areas. The individual PAH distributions in the December 2002 sampling off-Galicia were dominated by alkyl-naphthalene derivatives, consistently with the pattern distribution shown by the fuel-oil water accommodated fraction. The higher concentrations were found in the subsurface samples along the Costa da Morte, the area most heavily affected by the spill (av. 0.46 microg/L Sigma16 PAHs). The rest of the samples collected in other areas exhibited lower concentrations and a more even distribution of 2-4 ring PAHs, that ranged from 0.09 to 0.37 microg/L (av. 0.15 microg/L Sigma16 PAHs), with decreasing trends offshore and downward the water column. In September 2003, the values were rather uniform, averaging 0.09 microg/L (Sigma16 PAHs).  相似文献   
850.
A two year survey of benthic primary production during periods of emersion was performed on two stations of an intertidal mudflat (a muddy-sand station and a muddy station) in the Seine Estuary (English Channel, France). The goals of this study were to investigate the seasonal variations of metabolism, to estimate daily potential primary production variation at the annual scale and to estimate the annual potential primary production of the mudflat. Primary production and respiration were estimated by in situ measurements of carbon dioxide fluxes. Chlorophyll a concentration exhibited a great variability on both locations. Gross community production ranged from ca. 0 to 77 mg C m(-2) h(-1) at the muddy-sand location and from ca. 0 to 122 mg C m(-2) h(-1) at the muddy location. Community respiration showed a seasonal trend following temperature variations (up to 28.51 mg C m(-2) h(-1) in the muddy-sand and up to 23.40 mg C m(-2) h(-1) in the mud). Daily potential primary production was calculated, according to seasonal variations of photosynthetic parameters calculated using three photosynthesis versus irradiance curves obtained for the muddy location. The annual gross community primary production was 135 g C m(-2) yr(-1), leading to a low autotrophic annual budget, considering an annual community respiration of 110 g C m(-2) yr(-1).  相似文献   
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