黑海西北部冷泉碳酸盐岩的沉积岩石学特征及氧化还原条件的稀土元素地球化学示踪   总被引：3，自引：1，他引：2  

冯东  陈多福 《现代地质》2008,22(3):390-396

黑海西北部罗马尼亚大陆架(水深120m)和乌克兰陆坡(水深190m)发育冷泉碳酸盐岩结壳。XRD测试表明此结壳主要由高镁方解石和文石组成。结壳中与渗漏系统微生物活动有关的凝块和葡萄状文石等特殊的沉积组构非常发育。冷泉碳酸盐岩酸可溶部分(碳酸盐岩相矿物)的稀土元素含量很低(0.068×10-6~2.817×10-6),稀土元素页岩标准化配分模式显示罗马尼亚大陆架冷泉碳酸盐岩具有明显的Ce负异常,乌克兰陆坡冷泉碳酸盐岩具Ce的正异常,表明它们是分别在氧化和还原环境中沉积的。稀土元素和V、Cd和U等微量元素的含量在泥晶中最高,亮晶中最低,可能反映成岩过程对元素含量有控制作用。  相似文献   

填土表面倾斜时的主动土压力计算     

刘福臣  方静  林世乐 《岩土工程技术》2008,22(3):160-162,F0003

支护结构工程中,当坡顶填土表面倾斜时,无法采用常规的土压力理论进行计算。探讨了《建筑边坡工程技术规范》存在的问题,提出了推荐方法。通过算例验证了推荐方法,具有计算简单、计算结果合理的优点,可供工程设计中参考使用。  相似文献   

内蒙古敖包吐萤石矿床地质和地球化学特征   总被引：2，自引：0，他引：2  

许东青  聂凤军  江思宏  张万益  云飞  杨才  张天俊  吕旭光  林日亮 《地球学报》2008,29(4):440-450

笔者总结了敖包吐萤石矿床的地质特征,并通过萤石的稀土元素的地球化学和Nd同位素研究,探讨了该矿床的成矿作用和成矿物质来源。敖包吐萤石矿床产出于下二叠统大石寨组火山—沉积岩与燕山中期花岗岩的接触带,为单一萤石矿床。萤石矿石的稀土元素的含量(∑REE)变化范围为(8.04～30.04)×10-6,平均为19.42×10-6;轻重稀土LREE/HREE值0.24～0.65,平均0.52;LaN/YbN为0.07～0.62,平均0.26;δEu为0.42～0.90,平均0.60,具Eu负异常和明显重稀土富集的特征。岩矿石的Nd同位素研究表明,萤石矿石的εNd(t)都表现为很大的负值,以成矿主期年龄138Ma计算的εNd(138Ma)为-7.30～-30.55,具有古陆壳的演化特征,暗示其成矿的物质来源主要是壳源物质。在Moller的Tb/La-Tb/Ca成因判别图解中,敖包吐矿床的萤石的结晶作用表现为重新活化的趋势,反映流体具有混源的特征,既有热液成因,又有沉积成因。二叠世的海相火山活动通过海底喷气和喷流的作用形成了初始矿源层,而燕山中期花岗岩浆的侵位与结晶分异,又对初始矿源层的活化和富集提供了流体和热能的来源。成矿流体在经历了长期的演化后在大石寨组的构造薄弱破碎的的部位沉淀析出,形成敖包吐萤石矿床。  相似文献   

广州航空邮件处理中心土洞及桩端软土层处理工艺研究     

王干文 《中国煤炭地质》2008,(8):42-46

广州航空邮件处理中心位于岩溶发育地区,场区内存在大量土洞、溶洞等不良地质现象。该建筑物拟采用静压桩基础。为保证建筑物及场道安全,须对场区土洞进行处理。结合场地具体情况和施工工期要求,首先对大体积土洞进行泵注细石砼骨料充填处理,以消除地面大面积塌陷的危险,消灭压桩机械施工安全隐患,然后开始进行静压桩基础施工,同时在场地允许区域对中小体积土洞、桩端软土层等分别进行泵注砂浆骨料和袖阀注浆处理．以确保洞体密实和保证桩基承载力。通过对处理工艺、处理范围的比较筛选和对质量控制要点、施工技术要点的分析提炼．达到了施工简便、造价合理、安全高效的目的,并采用骨料取芯检测、土体标贯试验和压缩试验、洞体物探等多种检测手段,完全达到了设计要求,取得了良好的工程效果和经济效益。  相似文献   

“Tripoli”的含义及译名的讨论   总被引：1，自引：0，他引：1  

方邺森  顾炳伟 《岩石矿物学杂志》1993,12(1):91-94

“Tripoli”是一种新型的石英质工业矿物原料,在我国长期被误译为硅藻土,影响地质部门对这一新矿种的认识和寻找。本文追溯了“Tripoli”一名的由来,正确地阐述了“Tripoli”的本质特征,分析了在国内文献中长期被误译的根源,指明了其正确含义,并建议废除各种不正确的中译名,译为“粉石英”。  相似文献   

Effects of low molecular weight organic acids on sorption and desorption behavior of p-chlorophenol by yellow earth     

Daoyong ZHANG Xiangliang PAN Shuimu LIAO Chenglin HUANG Jingmei ZHANG 《中国地球化学学报》2006,25(B08):133-133

Low molecular weight organic acids （LMWOAs） are important components of root exudates. They play an important role in immobilizing and remobilizing contaminants in rhizospheric soil. Effects of four LMWOAs on the sorption and desorption behavior of p-chlorophenol by yellow earth was studied in batch mode. The results showed that the previous application of LMWOAs to enhanced adsorption capacity of p-chlorophenol of the soil in the order of maleic acid〉malic acid〉oxalic acid〉citric acid. However, when LMWOAs were applied to soil where p-chlorophenol had been previously adsorbed, substantial p-chlorophenol was desorbed from soil by oxalic acid, whereas citric acid, malic acid and maleic acid didn＇t desorb as much p-chlorophenol from soil as deionized water.  相似文献   

Monazite behaviour and age significance in poly-metamorphic high-grade terrains: A case study from the western Musgrave Block, central Australia     

Nigel M. Kelly  Geoffrey L. Clarke  Simon L. Harley 《Lithos》2006,88(1-4):100-134

Integrated, in situ textural, chemical and electron microprobe age analysis of monazite grains in a migmatitic metapelitic gneiss from the western Musgrave Block, central Australia has identified evidence for multiple events of growth and recrystallisation during poly-metamorphism in the Mesoproterozoic. Garnet + sillimanite-bearing metapelite underwent partial melting and segregation to palaeosome and leucosome during metamorphism between 1330 and 1296 Ma, with monazite grains in leucosome recording crystallisation at 1300 Ma. Monazite breakdown during melting is inferred to have occurred in the palaeosome. During a subsequent granulite facies event at 1200 Ma, deformation and metamorphism of leucosome and palaeosome resulted in partial disturbance of ages and potential minor growth on 1300 Ma monazite in leucosome. Growth of new, high-Y (+HREE) monazite in palaeosome domains occurred during garnet breakdown in the presence of sillimanite to cordierite and spinel, as a result of post-peak isothermal decompression. Diffusive enrichment of resorbed garnet rims in Y + HREE suggests garnet breakdown occurred slower than volume diffusion of REE. Monazite in both palaeosome and leucosome were subsequently partially to penetratively recrystallised during a retrogression event that is suggested to have occurred at 1150–1130 Ma. The intensity of recrystallisation and disturbance of ages appears linked to proximity to retrogressed garnet porphyroblasts and their occurrence in the relatively reactive or ‘fertile’ local environments provided by the palaeosome/mesosome volumes, which caused localised changes in retrogressive fluids towards compositions more aggressive to monazite. Like reaction textures, it is apparent that domainal equilibrium and reaction may control or at least strongly influence monazite REE and U–Th–Pb chemistry and hence ages.  相似文献   

New Approach for Estimation of Static and Seismic Active Earth Pressure   总被引：1，自引：1，他引：1  

Deepankar Choudhury  Shailesh Singh 《Geotechnical and Geological Engineering》2006,24(1):117-127

To estimate static and seismic active earth pressure (P_ad) on a rigid retaining wall, numerical analyses using different step sizes have been carried out in this paper, based on the modified Culmann line method by considering Coulomb’s planar rupture surface. Equivalent pseudo-static seismic forces are considered in the analysis. A new concept of modified unit weight by considering ground surcharge is introduced under static and seismic conditions. By numerical analysis, area of soil (A) has been estimated to obtain the ratio of A/A₀ where A₀ is θh², θ is the angle between retaining structure and ground surface and h is the vertical height of the wall. This ratio remains constant for a particular type of soil and has been used to estimate the maximum active earth pressure using force diagram. Results are provided in tabular form for easy calculation of the coefficient of static and seismic active earth pressure. Present results by considering the new technique, compares well with the results obtained by earlier researchers.  相似文献   

The multilevel fast multipole method for forward modelling the multiply scattered seismic surface waves   总被引：1，自引：0，他引：1  

Özcan Çakir 《Geophysical Journal International》2006,167(2):663-678

  相似文献   

华南地区晚二叠和晚三叠世煤中稀土元素特征研究   总被引：2，自引：0，他引：2  

杜美霞  庄新国 《中国煤田地质》2006,18(2):22-26

在华南地区贵州六盘水、江西乐平、露庆和湖北黄石矿区晚二叠和晚三叠世煤层的稀土元素ICP—MS分析数据的基础上，系统研究了研究区煤中稀土元素的含萤分布特征、赋存特征、配分模式以及地质控制因素。含量分布表明晚二叠世稀土元素含量总体高于晚三叠世；煤中稀土元素与灰分成正相关关系，部分煤样品由于有富稀土元素的重矿物组合的存在而出现稀土元素的异常高值；同一矿区、同一时代煤中稀土元素的配分模式具有一定的相似性，而不同地区同一时代和同一地区不同时代煤中稀土元素的配分模式具有较大差异；煤的沉积环境，煤中无机矿物组成以及海水的影响是控制煤中稀土元素含量和配分模式的主要地质因素。  相似文献