Generation and accumulation of Quaternary shallow gas in eastern Qaidam Basin, NW China     

苏爱国赵文智  党玉琪张水昌黎茂稳  庞雄奇周瑞年管自强  徐子远张道伟谭彦虎  陈践发李素梅 《中国地球化学学报》2006,25(1):43-55

1INTRODUCTION SHALLOW(MOSTLYBIOGENIC)GASACCOUNTSFOROVER20%OFTHEWORLD’SDISCOVEREDGASRESERVES(RICEAND CLAYPOOL,1981;CLAYPOOLANDKAPLAN,1974),AND REPRESENTSONEOFTHEUNCONVENTIONALENERGYSOURCES THATINCREASINGLYATTRACTTHEATTENTIONOFPETROLEUMGEOL OGISTS.NUMEROUS…  相似文献   

Technical Note Reactive silica and strength of fly ashes     

P.V. Sivapullaiah  J.P. Prashanth  A. Sridharan  B.V. Narayana 《Geotechnical and Geological Engineering》1998,16(3):239-250

The use of fly ash in geotechnical engineering depends greatly on its pozzolanic reactivity. Though many factors influence the reactivity of fly ash it is well recognized that reactive silica and lime content play a major role. A new, accurate and reliable method for the determination of reactive silica content of fly ash has been established. The reactive silica content, obtained as acid soluble silica in about 2 to 3 N hydrochloric acid, is found to correlate well with unconfined compressive strength of fly ashes. The reactive silica content of fly ash is also important in the stabilization of soils using fly ash. © Rapid Science Ltd. 1998  相似文献   

二氧化硅溶解度方程和地温计   总被引：8，自引：0，他引：8  

张生  李统锦 《地质科技情报》1997,16(1):53-58

对地表至下地壳和上地幔温压条件下二氧化硅溶解度实验研究的进展进行了综述，并给出了石英和非晶质ＳｉＯ２在纯水和盐水溶液中的溶解度定量方程，介绍了估算地热库温度的ＳｉＯ２地质温度计。  相似文献   

Magnetofossils in the sediment of Lake Baikal, Siberia   总被引：1，自引：0，他引：1  

J.A. Peck  J.W. King 《Earth and Planetary Science Letters》1996,140(1-4):159-172

A multidisciplinary approach involving rock-magnetics, transmission electron microscopy, and X-ray diffraction was used to identify a biogenic magnetite component in the Lake Baikal, Siberia, sedimentary magnetic record. The distinctive biogenic component to the magnetic record occurs as chains of single-domain, elongate hexagonal and tear-drop cone-shaped magnetite particles. These magnetofossils are inferred to be magnetosomes produced by magnetotactic bacteria living in the surficial sediment throughout Lake Baikal. Postdepositional reduction diagenesis results in the loss of the fine-grained magnetofossils at depth. In addition, this study shows that the fine-grained magnetofossils are removed by the process of storage diagenesis during long periods (21 months) of core storage, which results in a change to a coarser grained, slightly higher coercivity bulk magnetic mineral assemblage. Although the Lake Baikal sedimentary magnetic record has several distinct and complex components, by determining their origin this study has shown that the sediments are well suited for environmental magnetic study.  相似文献   

Time dependence of organic matter decay and mixing processes in Framvaren, a permanently anoxic fjord in South Norway     

David W. Dyrssen  Per O. J. Hall  Conny Haraldsson  Melissa Chierici  Jens M. Skei  H. Göte östlund 《Aquatic Geochemistry》1996,2(2):111-129

Three different layers have been identified in Framvaren, which has a maximum water depth of 184 m. One oxic layer above the redoxcline at 18–20 m. One anoxic layer from 20 to 100 m which is occasionally ventilated by a flow over the sill (which has a depth of 2.5 m), and finally a stagnant layer below 100 m. Using the release rate of silica from the bottom and measurements of the concentration of HTO it is possible to make some calculations on the annual volume of interleaving in the layers 25–50 m, 50–75 m, and 75–100 m together with the advective flows. Reliable values of the sulfide concentration were obtained by precipitating and weighing HgS together with careful protection of all anoxic water samples with argon. The light yellow color of the precipitate in the depth range 25 to 80 m indicates that the occasional ventilation will cause such reactions as 0.50₂ + H₂S S(colloidal) + H₂O. The elemental sulfur, being stabilized with HS^–, is set free upon the precipitation of HgS. The new data for the concentration of sulfide give an acceptable stoichiometry for the decay reaction of organic matter. This is not the case with the data of Yao and Millero. The mean values for the concentrations of ammonium and phosphate agree with the new data of Yao and Millero. The mol/mol C/N ratio of 10.1 found in trapped material by Naess and coworkers (1988) agrees with the stoichiometry of the dissolved constituents, i.e. C/N = 9.92 ± 0.45. A denitrification reaction is suggested to explain the high values of C/N. The vertical diffusion coefficient at 100 m calculated from the depth profile of silica was 0.92 × 10^–6 m² s^–1 which lies in the range of values given by Fröyland. Finally, the ¹⁴C age of the total dissolved inorganic carbon (Ct) in the water below 90 m was about 1600 years indicating a bioproduction in the period 8000 years B.P. to A.D. 1853 when a channel was opened between the fjord outside (Helvikfjord) and Framvaren.  相似文献   

Chemistry of high mountain lakes in siliceous chatchments of the Central Eastern Alps     

Roland Psenner 《Aquatic Sciences - Research Across Boundaries》1989,51(2):108-128

Alpine lakes in siliceous catchments of Tyrol and Carinthia (Austria) show signs of acidification. About 9% of the studied lakes have no alkalinity, more than 20% are below pH 6. About two thirds of all lakes have acid neutralizing capacities below 100 eq 1^–1. In spite of moderate precipitation acidity, some lakes show considerable concentrations of dissolved reactive aluminum during or shortly after snowmelt. High altitude lakes of the Alps are definitely more acidic than high mountain lakes in remote areas. Large differences in water and soil chemistry of nearby situated lakes were attributed to heterogeneities of bedrock geology. Paleolimnological investigations on former pH values of five lakes, based on diatom assemblages in the sediment, showed different developments: recent and past acidification, stable conditions, and alkalinization.  相似文献   

沉积铁矿形成过程中的生物作用   总被引：3，自引：0，他引：3  

陈志明 《地球科学进展》1992,7(6):56-59

    沉积赤铁矿和层控黄铁矿、菱铁矿的成矿过程中都离不开生物的作用。不同情况下，其表现形式不尽相同。生物的活动形成赤铁矿受层石、毒球状黄铁矿以及有机质的还原作用由赤铁矿转变为菱铁矿。
    冀西北宣龙地区铁质叠层石和铁质核形石同心纹层中普遍含有微体古植物化石，属于低等蓝藻类，形态以丝状体为主，部分为羽状体，它们直接地参与了铁的成矿作用。
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Carbonate alteration of the Upper Mount McRae Shale beneath the martite-microplaty hematite ore deposit at Mount Whaleback, Western Australia     

Adam D. Webb  Gerald R. Dickens  Nicholas H. S. Oliver 《Mineralium Deposita》2004,39(5-6):632-645

The formation of large martite-microplaty hematite ore deposits in northwest Australia remains a contentious topic in part because important evidence supporting a unifying genetic model has not been observed at all deposits. Carbonate replacement of silica has been found along normal faults below ore at the Mount Tom Price and Giles Mini deposits, which suggests an early hypogene process during ore formation. However, such rocks have not been identified at the largest martite-microplaty hematite deposit, Mount Whaleback. In this study, samples of the Mount McRae Shale are examined for their chemistry, mineralogy and petrography. These samples were collected from several key locations, including an area that immediately underlies ore along the Mount Whaleback fault at Mount Whaleback. Compared to unaltered black Mount McRae Shale from Wittenoom Gorge in the north and altered black and red Mount McRae Shale at Mount Whaleback, reddish-green Mount McRae Shale along the Mount Whaleback fault is greatly enriched in MgO and CaO and depleted in SiO₂. This chemistry arises from significant amounts of fine- to medium-grained ferroan-dolomite and ankerite and cross-cutting chlorite and carbonate veins. The composition is distinct from that produced during regional metamorphism, and most likely represents hydrothermal alteration after metamorphism. The lack of carbonate-rich, silica-poor rocks in the overlying Dales Gorge Member at Mount Whaleback is consistent with pervasive oxidation of most rocks in the region during or after ore genesis, a process that removed carbonates. Although several questions remain unanswered, these results support models that invoke an early hypogene stage during the formation of the martite-microplaty hematite deposits in the Hamersley Province.Editorial Handling: B. Lehmann  相似文献   

纳米硅粉水泥土的强度特性及固化机理研究   总被引：8，自引：0，他引：8  

王文军  朱向荣 《岩土力学》2004,25(6):922-926

将性能优异的纳米硅粉作为外掺剂应用于水泥土改性研究。通过室内试验，探讨了纳米硅粉水泥土的强度特性。试验表明，一定掺量下的纳米硅粉能够显著提高水泥土的各个龄期强度。结合试验测试和理论分析，探讨了纳米硅粉在水泥水化硬化过程中的作用以及纳米硅粉与土之间的作用，在此基础上，分析了纳米硅粉改性水泥土工程性状的机理，旨在为纳米硅粉应用于工程实践开展理论和试验研究探索。  相似文献   

非常规含气系统的研究和勘探进展   总被引：14，自引：2，他引：14  

陈建渝  唐大卿  杨楚鹏 《地质科技情报》2003,22(4):55-59

从含油气系统的观点出发，分别总结了煤层气、盆地中心气、裂缝型页岩气、浅层生物气和天然气水合物五类非常规含气系统的地质和地球化学特征，修改和补充了传统油气系统的概念，为天然气新领域的开拓和发展提供了新的思路。常规天然气藏为浮力驱动的存在于构造或地层圈闭中的独立气藏，而非常规天然气藏一般不是浮力驱动的聚集气藏，它们在区域上呈连续弥散的聚集，常常与构造和地层圈闭无关，因此，它们的成藏要素和过程与常规天然气藏有所区别。在煤层气和页岩气中，烃源岩既是储层，又是盖层且运移距离很短；储层多为低孔隙度、低渗透性的裂缝型储层，主要为毛细管力和水力封闭，大型煤层气藏可以出现在向斜构造中。  相似文献