特征分析法在广西南丹芒场锡——多金属矿田隐伏矿床预测中的应用          下载免费PDF全文

沈镭 《地质找矿论丛》1990,5(4):80-89

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322矿田花岗岩与铀矿床的同位素研究     

沈吉  赵乙英 《铀矿地质》1990,6(4):213-219

本文应用同位素地质方法研究322矿田内花岗岩的年龄和成因、成矿热液和成矿物质来源等问题。研究表明,矿田内的成矿母岩为改造型花岗岩,其Rb-Sr同位素年龄为198.8Ma,成矿热液来自花岗岩结晶矿物颗粒间和裂隙中的溶液以及大气降水。成矿物质主要来自花岗岩,部分也来自岩体周围的寒武系地层。  相似文献   

较低温度(580～700℃)合成的高Tc(Tl-Ba-Ca-Cu-O)系超导体     

孟大维  王永在  沈今川  吴秀玲  周惟公 《地球科学》1990,(4)

按照名义组分1113和1112以较低的烧结温度(580～700℃)获得了一系列高Tc Tl-Ba-Ca-Cu-O系超导体,其最佳样品的零电阻温度为112K。电子衍射分析表明,样品中含有两相,主相属四方晶系,晶胞参数为a=b=0.547nm.c=2.931nm.α=β=Υ=90°,空间群为I4/mmm次相属正交晶系,晶胞参数为a=0.335nm,b=0.989nm.c=1.654nm,.α=β=Υ=90°,空间群为Pmmm。  相似文献   

旋转台法鉴别斜长石双晶律   总被引：1，自引：0，他引：1  

沈上越 《矿物岩石》1990,10(3):33-40

用旋转台法鉴别斜长石双晶律,在A.C.马富宁“斜长石主要双晶鉴别图的基础上。把11种⊥a切面增为17种,并绘制了立体图.对比斜长石双晶律和系统研究斜长石特征,应分别采用A.李德曼法和D.B.斯利蒙斯法,并举例详述了后者的应用.  相似文献   

AN ANALYSIS ON THE STRUCTURE TYPES AND BENEFITS OF SLOPELAND AGROFORESTRY SYSTEMS-Taking the Three Gorge Reservoir Area As An Example     

Shen Yuancun  Leng Shuying  Zhang Yongtao 《地理学报(英文版)》1995,(4)

Chinahasalongltist0ryofaghcLIlturaldeveloPn1atn1edeveloPmatandLttilizahonofplanlsaremoreextensivethanthatofmotUAsinsandhills.Underthepressureofil11Promplivingstandardf0rl.2billionpeOPleatpresa1t,itistmdoubtedtoaCCeeratesl0PelanddeVeopmat.HOWdowerealizehig…  相似文献   

Public housing and migration: a multi-level modelling approach     

Boyle P  Shen J 《International journal of population geography : IJPG》1997,3(3):227-242

"This paper...[analyzes] the distance moved by one-year migrants using a multi-level modelling approach. Controlling for a range of socio-economic variables, derived from the 1991 British Census Sample of Anonymised Records (SAR), at both the individual and area level, the distance moved by household heads in public, privately rented and owner-occupied housing within Britain is assessed.... It is confirmed that migrants in public housing are less likely to migrate long distances than owner-occupiers and that the proportion of public housing in a SAR area, and the absolute reduction in public housing in a SAR area between 1981 and 1991, does not have a significant effect on the distance that in-migrants have moved."  相似文献   

中国区域缺水问题的发展趋势与解决对策   总被引：5，自引：0，他引：5  

沈大军 《地球科学进展》1996,11(4):342-349

分析了建国以来我国两个缺水阶段的特点，即第一阶段是由农田灌溉面积快速发展引起的，第二阶段是供水能力增长缓慢造成的；然后根据我国工业发展速度、宜农荒地面积和农田灌溉面积的增长情况，分５个地区对我国２１世纪的水资源需求进行了预测，２１世纪我国的需水量将持续增长，至２０５０年达９５０×１０９ｍ３，但供水发展缓慢，因此我国２１世纪上半叶区域缺水问题严重。最后提出了解决我国区域缺水问题的四条对策，即开源、节流、加强污水处理与扩大资金投入  相似文献   

Late Pleistocene - Holocene slip history of the Langshan-Seertengshan piedmont fault (Inner Mongolia,northern China) from cosmogenic <Superscript>10</Superscript>Be dating on a bedrock fault scarp     

Xiao-ming Shen  De-wen Li  Yun-tao Tian  Yan-wu Lv  Da-wei Li  Yan-feng Li 《山地科学学报》2016,13(5):882-890

Offset geomorphic features and deformed late Quaternary strata indicate active deformation along the Langshan-Seertengshan piedmont fault (LSPF), one of the most active faults in the Hetao fault zone in Inner Mongolia, North China. The widespread occurrence of bedrock fault scarps along the LSPF offers excellent opportunity to examine the faulting history. Using cosmogenic ¹⁰Be exposure dating, we measured the exposure ages of the western Langshankou scarp, located in the middle segment of the LSPF. Our data revealed at least two earthquakes that occurred at 22.2±3.3 ka and 7.2±2.4 ka, respectively. These events are consistent with previous paleoseismic trench studies. The regression of the relationship between the age and sampling height along the scarp yield a fault slip rate of 0.10 +0.05/-0.06 mm/yr, which is significantly lower than the average post-late Pleistocene fault slip rate of ~1 mm/yr, as estimated from the offset of the T2 terraces by previous studies. This indicates that the slip of the LSPF may have been accommodated by other fault branches.  相似文献   

Composition and distribution of planktonic ciliates in the southern South China Sea during late summer: Comparison between surface and 75 m deep layer     

Huaxue Liu  Pingping Shen  Chunhou Li  Zuozhi Chen  Zhanhui Qi  Honghui Huang 《中国海洋大学学报(英文版)》2016,15(1):171-176

Ciliates are very important components in most marine ecosystem.They are trophic link between the microbial food web and grazing food chain.In this study,ciliates were collected from 11 sites in the southern South China Sea(SCS) during August 25 to September 28,2011.Their composition and distribution at the surface and 75 m deep depth of the ocean were studied.A total of 30 species belonging to 22 genera were identified,and 22 species of 15 genera were Tintinnids.Eutintinnus fraknoii and E.stramentus were the most common species.The other dominants were strombidiids ciliates including Strombidium conicum and S.globosaneum,which were followed by the tide form,Mesodinium pulex.Ciliates abundance ranged from 46 ind L~(-1) to 368 ind L~(-1) in the open sites,46–368 ind L~(-1) at surface and 73–198 ind L~(-1) at 75 m deep layer.In the Yongshu reef,ciliates abundance ranged from 167 ind L~(-1) to 365 ind L~(-1) in the water column,similar to that in Sanya coral reef waters.Ciliates composition showed obvious difference between surface and 75 m deep layer at station S2(P 0.05),while no similar result was observed at other sites.At 75 m deep layer,salinity was negatively related to mixed layer depth(P 0.05),but positively to chlorophyll a concentration(P 0.05),indicating that the change of vertical mixing in water column influenced vertical distribution of ciliates in the southern SCS.  相似文献   

A framework to analyze vulnerability of critical infrastructure to climate change: the case of a coastal community in Florida     

Suwan Shen  Xi Feng  Zhong Ren Peng 《Natural Hazards》2016,80(1):589-604

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