黔北务正道地区铝土矿形成环境的古盐度识别     

崔滔  焦养泉  杜远生  余文超  计波  雷志远  翁申富  金中国  和秀林 《地质科技情报》2013,(1):46-51

通过对黔北务川—正安—道真铝土矿中的B、Sr、Ba、V、Zr及其生物标志化合物的分析,对务正道地区铝土矿沉积环境的古盐度进行了研究。结果表明,铝土矿的沉积受到海洋环境的影响,主要形成于半咸水-淡水环境中。沉积环境为半封闭海湾,海侵使成矿区低盐度水体变为半咸水或咸水,随后陆地淡水输入等淡化作用将半咸水或咸水淡化,淡化的程度与范围取决于淡化时间的长短,经淡化后的水体在下一轮海侵中再次被咸化,水体的古盐度随海平面升降在淡水-咸水之间循环。  相似文献   

南太行山平顺闪长岩体SHRIMP锆石U-Pb年龄、地球化学特征及地质意义     

张海东  高海龙  刘建朝  张苏楠  彭素霞  王瑞美  吴继莲  黄水文 《地质科技情报》2013,(2):41-49

南太行山平顺闪长岩锆石SHRIMP测年表明闪长岩体形成于(125.5±2.3)Ma,与太行山其他地区乃至整个华北地区侵入杂岩体具有相近的形成年代,表明在晚中生代(115～135Ma)太行山地区与华北地区经历了相同的构造岩浆事件。平顺闪长岩w(SiO2)=48.57%～63.54%,w(Al2O3)=13.53%～19.15%,w(MgO)=1.20%～9.31%,w(TiO2)=0.34%～1.07%,w(CaO)=3.13%～10.39%,w(K2O+Na2O)=4.78%～7.99%,Mg#=0.37～0.72,LREE富集HREE亏损,略显微弱的正Eu异常,以富集LILE、LREE元素和亏损Nb-Ta等高场强元素为特征。闪长岩(206Pb/204Pb)i=17.775～18.857,(207Pb/204Pb)i=15.522～15.602,(208Pb/204Pb)i=38.044～38.502,εNd(125Ma)=-17.009 56～-9.606 32,ISr=0.705 85～0.707 53,表明起源于EMI富集地幔,并受到地壳物质和EMII型富集地幔混染,可能说明在晚白垩世太行山地区与整个华北克拉通都发生了岩石圈减薄事件。  相似文献   

黔北务正道地区铝土矿层中燃烧成因PAHs的发现及其古气候意义     

余文超  杜远生  汪小妹  黄兴  崔滔  喻建新  覃永军 《地质科技情报》2013,(1):57-61

铝土矿沉积被认为是炎热潮湿热带或亚热带古气候条件下的气候敏感沉积物。对黔北铝土矿中3个钻孔不同层位岩心样品的GC-MS检测显示,样品中含有种类丰富、相对含量较高的燃烧成因多环芳烃化合物(PAHs)。以芘、荧蒽、苯并[a]芘、苯并[e]芘、苯并[ghi]苝等为代表的燃烧成因PAHs与陆上火灾事件密切相关。结合生物标志物特征及前人研究所得的古地磁、植物与孢粉化石证据,认为黔北铝土矿形成时陆上存在丰富的植被,且是一种在炎热潮湿背景下存在季节性干湿分异的古气候条件。  相似文献   

黔北务正道地区铝土矿鲕状矿石中鲕粒的微区元素地球化学特征及其成矿意义     

张亚男  张莹华  吴慧  丁晓英  凌文黎  雷志远  翁申富  马倩  杜远生 《地质科技情报》2013,(1):62-70

铝土矿矿床中普遍含有不同比例的鲕状矿石,但目前对这些鲕粒的成因及其与成矿作用相互关系的了解相对有限。对贵州务正道地区铝土矿矿床中典型鲕状矿石中鲕粒进行了微区原位主量元素电子探针分析(EPMA)和激光剥蚀等离子体质谱(LA-ICP-MS)主量和微量元素分析,并与共存基质的元素组成进行了对比。研究表明,鲕粒的形成时间晚于基质,地表化学风化作用本身并不能导致铝土矿的形成;鲕粒的形成发生于强氧化和高酸度的环境,其成因被解释为在海进过程中在地层中一定的深度条件下形成了以黄铁矿为主的硫化物矿物,随后的海退作用过程导致硫化物蚀变并形成强酸环境,使得成矿元素Al相对于杂质元素(Si、Fe)发生相对富集,且该过程具有多期次振荡重复的特点。铝土矿形成是热带湿热气候条件下周期性海进-海退循环与长期的大陆古隆起区平坦海岸地形相互耦合的结果。  相似文献   

The effect of spatial distance on the discriminability of colors in maps     

Alžběta Brychtová  Arzu Çöltekin 《制图学和地理信息科学》2013,40(3):229-245

<b>ABSTRACTb>

The spatial distance (gap) between map symbols can have a great impact on their discriminability, however, there is little empirical evidence to establish spatial and attribute thresholds. In this paper, we examine the effect of the spatial gap in discriminability of color hue and value, that is, we conducted an online study to obtain performance metrics; then an eye-tracking study to understand participants’ strategies and cognitive processes. Participants completed two experimental tasks (compare two areas and decide if their color is the same; and compare three areas and rank them from the lightest to the darkest). The color distances and the spatial distances were strictly controlled for the compared areas. Our analyses confirmed that, overall, increasing the gap between colors has a consistent negative impact on the ability to differentiate them with both sequential and qualitative schemes. Furthermore, we observed that sequential schemes require larger color distances than qualitative schemes for discriminability. Finally, our results suggested that for qualitative colors, the largest tested color distance ?Eb>00b> = 10 yields considerably higher levels of accuracy in color discrimination (even when the spatial gap between the two colors is large), thus we recommend ?Eb>00b> = 10 to practicing cartographers and other information visualization designers.  相似文献   

广西公路建设对生物多样性的潜在影响   总被引：2，自引：0，他引：2  

黄晓霞  江源  丁佼  和克俭  张勇  秦雨 《热带地理》2013,33(1):70-75

根据广西的生物多样性特征,以及因公路网络对景观结构的改变而造成的对生物多样性的潜在影响,文章主要通过公路阻隔效应指数(I)及公路对生物多样性影响指数(B),运用GIS技术,以5 km×5 km的像元为单元格计算各指数的数值,从而确定广西公路建设对生物多样性影响的区域特征及差异.结果表明,桂北山区、桂西南岩溶山区和广西边缘山区是生物多样性最易受到公路建设影响的区域,这些地区的生物多样性敏感而特殊,需要特别注意采取必要的保护措施.  相似文献   

Prediction of Non-Cavitation Propeller Noise in Time Domain     

叶金铭  熊鹰  肖昌润  毕毅 《中国海洋工程》2011,(3)

The blade frequency noise of non-cavitation propeller in a uniform flow is analyzed in time domain. The unsteady loading (dipole source) on the blade surface is calculated by a potential-based surface panel method. Then the time- dependent pressure data is used as the input for Ffowcs Williams-Hawkings formulation to predict the acoustics pressure. The integration of noise source is performed over the true blade surface rather than the nothickness blade surface, and the effect of hub can be considered. The ...  相似文献   

孟州市府大楼整体搬迁岩土工程实录     

程礼来  段宗贵  宋永锟 《河南国土资源》1997,(3)

孟州市政府办公大楼整体搬迁的场地工程地质勘察，分部进行，即划分成搬迁路径和永久性地基两个单元。既做独立分析，又进行整体评价；既提供搬迁所需岩土工程指标，又为施工提出一些切合实际的建议。准确可靠的工程地质勘察资料，促成了大楼的整体迁移和永久定位。  相似文献   

Snap Tension in Mooring Lines of Deepwater Platform     

张素侠  唐友刚  刘海笑 《中国海洋工程》2009,23(3):415-428

Based on the theory of impact dynamics, the motion equations for a mooring line-floating body system before and after impact loading are established with consideration of the viscoelastic property of mooring lines. The factors that influence the taut-slack conditions of a mooring system are analyzed through classifying the taut-slack regions, which are defined by non-dimensional ratios of displacement, frequency, and damping of the system. The mooring system of Jip spar platform is analyzed, and the snap te...  相似文献   

Analysis on Buckling Performance of Submarine Pipelines During Deepwater Pipe-Laying Operation     

袁林  龚顺风  金伟良  李志刚  赵冬岩 《中国海洋工程》2009,23(2):303-316

Pipes inevitably encounter high ambient pressure and bending moment during the deepwater pipe-laying process,which can lead to elliptical buckling and even deterioration failure.For the safety of pipe-laying operation,available formalas for the pipe stability are established on the basis of the assumption of uniform deformation along the tube length and symmetrical buckling.This method can predict the nonlinear rcsponse of elliptical collapse of steel circular tubes for different ratios of diameter to thickness (D/t) under pure bending or combined bending and external pressure.In these formulas,the strain-displacement relationship is deduced from the nonlinear ring theory,and the Ramberg-Osgood constitutive model is applied to simulate the inelastic material behavior.Meanwhile,the principle of virtual work is adopted to derive the equilibrium equations.A set of equations is solved by the Newton-Raphson method,and the iterative scheme contains nested iteration for the constitutive relation.In order to check the effectiveness of this theoretical method,illustrative examples are presented in this paper.Besides,the numerical simulation is carried out by use of ANSYS.A comparison of the results shows that the theoretical method can provide reasonable prediction for engineering practice.  相似文献