辽南早元古宙变质热液型金矿床成矿机理探讨     

戴立军  樊秉鸿 《国土资源》1990,(2)

辽南早元古宙辽河群变质岩系中的金矿床为变质热液成因金矿床,矿床的形成与吕梁期变质变形作用关系密切。金矿化带的展布与金矿体的产出受韧性剪切带控制。剪切带内岩石具有明显的动态性组构特征,直接赋矿围岩为辽河群盖县组糜棱岩化千枚岩、变砂岩及云母石英糜棱岩等。韧性剪切带为含矿流体的运移提供通道。作者定义这类金矿床为变质热液型含金剪切带金矿床。  相似文献   

山东地壳运动GPS观测网的建设与初步结果分析   总被引：2，自引：2，他引：0  

李杰  殷海涛  张玲  董小娜 《大地测量与地球动力学》2007,27(Z1):9-13

简述山东地壳运动GPS观测网的建设和数据处理的基本方法，并对系统所得的初步结果进行分析，分析表明，该系统可产出连续、高精度的GPS基准站三维坐标及基线数据，可为地震监测和地壳运动的科学研究提供良好的GPS数据素材。  相似文献   

南秦岭古生代盆地演化中幕式流体过程及成岩成矿效应   总被引：2，自引：0，他引：2  

曾荣  刘淑文  薛春纪  龚建新 《地球科学与环境学报》2007,29(3):234-239

从南秦岭古生代盆地构造-沉积演化出发,通过分析古生界不同层位流体成岩成矿事实与盆地发展演化之间的关系,探讨了南秦岭早古生代—泥盆纪演化时期多幕流体过程和成岩成矿效应。幕式流体成岩成矿最早可追溯到早寒武世,区域上从东到西形成了重要的碳硅质岩中重晶石/毒重石矿床及金、铂族元素矿化;早、中志留世继续发展,形成了钠长石岩、重晶石岩、铁碳酸盐岩、硅质岩与铅-锌、金矿床;中泥盆世为最强烈的一次热水沉积活动,其规模大、热水沉积产物多样,形成了泥盆系硅质岩-钠长石岩-重晶石岩-铁白云石岩中的铅锌(铜)矿床、铁白云石硅质岩中铅锌(铜)矿床以及钠长石角砾-铁白云石板岩中金-铜矿床。  相似文献   

论四川盆地丘陵区防护林体系的建设     

钟祥浩 《山地学报》1990,(1)

四川盆地丘陵区,人多地少,资源贫乏,经济不发达,生态环境质量低劣,因而建设具有生态效益、经济效益和社会效益的防护林体系很有必要。建设本区防护林体系的原则应是:共生,布局与结构合理,土地资源充分利用和总体最优。经采取切实有效的措施后,最终建成一个良性农田生态防护林网络体系,以协调当地人口、资源、经济和环境之间的关系,并使其日臻完善。  相似文献   

中国城市地理学近期进展   总被引：11，自引：0，他引：11  

沈道齐  崔功豪 《地理学报》1990,(2)

中国城市地理学的兴盛时期始于70年代中期,至80年代进入历史以来最旺盛的发展时期。城市地理学主要研究城市体系、城市化、城市地域结构与具体的大小城镇。其重要的实践领域则主要通过城市规划和区域规划、国土规划。特别是70年代中期借助于我国城市规划工作的复兴,为城市地理学的发展提供了广阔的实践基础。  相似文献   

Effect of parallel electric field on electrostatic ion-cyclotron instability in anisotropic plasma in the presence of ion beam and general distribution function—Particle aspect analysis     

Ruchi Mishra 《Planetary and Space Science》2006,54(2):188-199

Dispersion relation, resonant energy transferred, growth rate and marginal instability criteria for the electrostatic ion-cyclotron wave with general loss-cone distribution in low-β anisotropic, homogeneous plasma in the auroral acceleration region are discussed by investigating the trajectories of the charged particles. Effects of the parallel electric field, ion beam velocity, steepness of the loss-cone distribution and temperature anisotropy on resonant energy transferred and growth rate of the instability are discussed. It is found that the effect of the parallel electric field is to stabilize the wave and enhance the transverse acceleration of ions whereas the effect of steepness of loss-cone, ion beam velocity and the temperature anisotropy is to enhance the growth rate and decrease the transverse acceleration of ions. The steepness of the loss-cone also introduces a peak in the growth rate which shifts towards the lower side of the perpendicular wave number with the increasing steepness of the loss-cone.  相似文献   

多源遥感数据的降水空间降尺度研究——以川渝地区为例   总被引：2，自引：0，他引：2  

嵇涛  刘睿  杨华  何太蓉  吴建峰 《地球信息科学学报》2015,(1):108-117

大量研究表明,通过传统地面气象站点实测的单点数据,不能有效地反映降水的空间变化特征。目前,以遥感数据获取的降水产品已得到了广泛的应用,但在地形地势复杂区域,遥感降水产品的空间分辨率与数据精度等方面仍然存在着极大的不足。因此,本文以四川重庆(川渝)地区为例,通过建立降水产品降尺度算法,以实现降水产品的降尺度估算,提高降水数据的空间分辨率。依据在不同尺度下(0.25°、0.50°、0.75°和1.00°),TRMM 3B43、地理因子,以及MOD13A3(NDVI)之间存在的相关关系,构建了多元回归模型。通过对比这4种尺度下的回归模型,选择其中精度最高的作为最终的降尺度算法,然后再把这种降尺度算法应用到1 km分辨率下进行降水估算。进一步,以区域差异分析(GDA)和区域比率分析法(GRA)对降尺度估算的降水数据进行校正,并结合部分地面气象站点实测的降水数据进行验证。验证结果表明:降尺度算法是可靠的,能有效提升降水产品的空间分辨率,同时GDA和GRA校正方法能减小误差,进一步提升降水估算的精度,满足区域地表过程应用的需求。  相似文献   

人类活动对海洋生态系统影响的空间量化评价——以莱州湾海域为例   总被引：2，自引：0，他引：2  

李延峰  宋秀贤  吴在兴  俞志明 《海洋与湖沼》2015,46(1):133-139

本文针对海域管理中难以量化人类活动对海洋生态系统影响的问题,提出人海关系空间量化模型,通过完善概念模型、构建指标体系、确定权重及标准,最终利用作用强度和位置关系量化人类活动对海洋生态系统的影响,数值在0—1之间,等分为四个影响程度,由弱到强依次为微弱、中等、强烈和极强,并将该模型和量化方法应用于莱州湾海域。研究结果表明:整个莱州湾受人类活动的综合影响均值为0.425,处于中等影响程度;其中污水排放、围填海工程及港口航运是对莱州湾生态系统影响比较强烈的人类活动;研究海域中40%受到人类活动的强烈影响,44%为中等影响,16%为微弱影响。空间量化分析显示,人类活动对莱州湾近岸海域的综合影响比邻近外海强烈,其中影响较强烈的区域出现在西南近岸海区,而影响较微弱的海区则为莱州湾北部外海。该方法空间量化结果与莱州湾实际情况相符,说明人海关系空间量化模型适合定量化评估人类活动对该海域生态系统的影响,可为"山东半岛蓝色经济区"海域管理提供技术支持。  相似文献   

山东半岛北部滨浅海区表层沉积物铝物源鉴别     

徐刚  刘健  裴绍峰  孔祥淮  胡刚  高茂生 《海洋学报(英文版)》2015,34(12):147-153

Surface sediment samples in the near shore area of the north Shandong Peninsula are collected for grain size and element analyses. The results indicate that the surface sediments in the study area are primarily composed of the silt-sized components similar to the Huanghe River. The total concentration of aluminum varies from 5.57% to7.37%(average(6.33 ± 0.40)%), and its spatial distribution is mainly controlled by the grain size. Correlations between the ratio of aluminum to titanium concentration and aluminum concentration, titanium concentration and the mean grain size indicate that aluminum in the near shore surface sediments is affected majorly by the terrigenous source, and partially by the anthropogenic source. The ratios of aluminum to titanium concentrations are larger than the background value of loess matter at some stations due to the existence of excess aluminum associated with human activities. Thus, the sources of aluminum should be identified firstly when aluminum is used as an index of terrigenous matter even in the near shore area dominated by terrigenous deposits.  相似文献   

Characteristics and origin of carbon isotopes of n-alkanes in crude oils from the western Pearl River Mouth Basin,South China sea     

《Marine and Petroleum Geology》2015

The quantitative characterization of carbon isotopes of n-alkanes is commonly carried out in organic geochemical studies. Possible controls on carbon isotopes include source organic matter, maturity, fractionation during oil expulsion and migration, and the mixing of different oils. In this study of the origin of crude oils in the western Pearl River Mouth Basin, the influences of all of these factors have been considered in reaching a conclusion. Carbon isotopes of n-alkanes in the crude oils, and the extracts of the two effective source rocks (the Wenchang and Enping formations) in the basin, exhibit clear differences. The Wenchang source rocks have heavy δ¹³C values that remain almost constant or become slightly heavier with increasing carbon number. The Enping source rocks have light δ¹³C values that become lighter with increasing carbon number. Two groups of oils in this area were identified based on the carbon isotopes of the n-alkanes; groupIoils are similar to extracts of the Wenchang source rocks. However, the groupIIoils are different from both the Wenchang and Enping source rocks and the carbon isotopic profiles of their n-alkanes exhibit a “V” feature with increasing carbon number. The results of artificial thermal maturation experiments indicate that, from the early stage to the peak stage of oil generation (with EasyRo between 0.64% and 1.02%), the δ¹³C values of n-alkanes in the pyrolysis oils become heavier by about 3‰ with increasing thermal maturity, but the shape of the carbon isotopic profiles are not significantly changed. Calculated δ¹³C values of n-alkanes in “mixed” artificial pyrolysis oils indicate that the mixture of oils generated from the same source rocks with different maturities could not change the carbon isotopic profile of the n-alkanes, however, a mixing of the Wenchang and Enping oils could give the “V” feature in the profiles, similar to the groupIIoils in this area. The groupIIoils appear to be mixed Wenchang and Enping oils, the latter being the dominant component in the mixture. We conclude that the source organic matter and the degree of mixing are the main factors controlling the carbon isotopic characteristics of n-alkanes in crude oils in the western Pearl River Mouth Basin.  相似文献