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381.
382.
《中华人民共和国地貌图集》的研究与编制 总被引:6,自引:4,他引:2
CHENG Weiming ZHOU Chenghu CHAI Huixia ZHAO Shangmin LIU Haijiang ZHOU Zengpo 《地理学报(英文版)》2011,21(1):89-100
Geomorphologic maps are one of the most fundamental materials of the natural environment. They have been widely used in scientific research,resource exploration and extraction,education and military affairs etc. An editorial committee was established in 2001 to collect materials for researching and compiling a set of new 1:1,000,000 geomorphologic atlas of China. A digital geomorphologic database was created with visual interpretation from Landsat TM/ETM imageries and SRTM-DEM etc. The atlas compiled from the database was finished. The main characteristics of the atlas are as follows:Firstly,Landsat TM/ETM imageries,published geomorphologic maps or sketches,geographical base maps,digital geological maps,and other thematic maps were collected,which were uniformly geometrically rectified,clipped into uniform sheets,and stored in the foundation database. Secondly,based on the legends of 15 sheets 1:1,000,000 maps published in the 1980s,a geomorphologic classification system was built by combining morphology and genesis types. The system comprised seven hierarchical layers:basic morphology,genesis,sub-genesis,morphology,micro-morphology,slope and aspect,material composition and lithology. These layers were stored in the database during visual image interpretation. About 2000 kinds of morpho-genesis and 300 kinds of morpho-structure were interpreted. Thirdly,the legend system was built,which included color,symbol bases and note bases etc.,compilation standards and procedures were developed,74 sheets of 1:1,000,000 covering all land and sea territories of China were compiled,the 1:1,000,000 geomorphologic atlas of the People’s Republic of China was finished and published. The atlas will fill the blanks in national basic scale thematic maps,and the geomorphologic database could be applied widely in many fields in the future. 相似文献
383.
泥质含量及其分布形式对岩电关系影响的数字岩心仿真(英文) 总被引:2,自引:1,他引:1
由于泥质所造成的附加导电现象,泥质含量及其分布形式对电阻率增大系数I和含水饱和度Sw关系具有重要影响,由于岩石物理实验中岩心孔隙结构及其组分构成、分布的微观不可调性,因而泥质分布形式所造成的影响很难通过岩心实验来单独研究。基于数字岩心的格子气自动机方法是一种有效的微观数值模拟方法,本研究利用储层岩心薄片的骨架颗粒尺寸信息资料建立数字岩心模型,结合格子气自动机技术对数字岩心不同饱和流体情况下电的传输特性进行数值模拟研究,揭示了不同泥质含量和泥质分布形式对孔隙介质导电特性非阿尔奇现象产生的影响,建立饱和度指数和泥质含量之间的关系模型,其良好的吻合性表明该方法在岩石物理研究中是一种十分有效的研究方法,而新模型适于在非阿尔奇储层进行准确的饱和度评价。 相似文献
384.
Evidence for wildfire in the Meishan section and implications for Permian-Triassic events 总被引:1,自引:0,他引:1
Wenjie Shen Yongge Sun Yangting Lin Pingxia Chai 《Geochimica et cosmochimica acta》2011,75(7):1992-1372
Polynuclear aromatic hydrocarbons (PAHs) and black carbon (BC) in sediments are powerful tools in the identification of the combustion process throughout geologic history. In this study, combustion-derived PAHs and BC were carefully investigated in sediments from the Global Stratotype Section and Point of the Permian-Triassic (P/Tr) boundary in Meishan, China. Quantitative analyses of combustion-derived PAHs and BC demonstrate anomalously high concentrations in the boundary event beds that coincide with the mass extinction horizon. The prevalence of parent polynuclear aromatics (e.g., phenanthrene) in PAHs, together with non-metric multidimensional scaling analysis, confirms that the PAHs are mainly derived from vegetation burning instead of having a coal and/or oil origin. BC detected in sediment occurs in various forms from large irregular charcoal particles to fine aciniform soot, with an equivalent reflectance of up to 3.5%. The results strongly suggest that a wildfire occurred during the P/Tr boundary, which served as one of the possible triggers of mass extinction on land. The wildfire occurrence indicates that the O2 concentration of the atmosphere during (or before) the P/Tr mass extinction was probably >17%. The temporal coincidence of the mass extinction with intensive volcanic eruption, marine anoxia and wildfire events in the region of the Meishan section provides new insight into the mechanisms of the P/Tr biotic crisis. Our results show that wildfires could have played an important role in the collapse of the ecosystem in the Meishan P/Tr events. 相似文献
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386.
Experimental studies of the effects of thermochemical sulfate reduction (TSR) on light hydrocarbons were conducted in sealed gold tubes for 72 h at 400 °C and 50 MPa. A variety of pyrolysis experiments were carried out, including anhydrous, hydrous without MgSO4 (hydrous experiments) and hydrous with MgSO4 (TSR experiments). Common reservoir minerals including montmorillonite, illite, calcite and quartz were added to various experiments. Measurements of the quantities of n-C9+ normal alkanes (high molecular weight, HMW), n-C6-8 normal alkanes (low molecular weight, LMW), C7-8 isoalkanes, C6-7 cycloalkanes and C6-9 monoaromatics and compound specific carbon isotope analyses were made. The results indicate that TSR decreases hydrocarbon thermal stability significantly as indicated by chemically lower concentrations and isotopically heavier LMW saturated hydrocarbons in the TSR experiments compared to the hydrous and anhydrous experiments. In the LMW saturated hydrocarbon fraction, cycloalkanes tend to be more resistant to TSR than n-alkanes and isoalkanes. TSR promotes aromatization reactions and favors the generation of monoaromatics, resulting in higher chemical concentrations and isotopically equivalent compositions of monoaromatics in the anhydrous, hydrous and TSR experiments. This indicates that LMW monoaromatics are thermally stable during the pyrolysis experiments. Acid rather than basic catalyzed ionic reactions probably play a major role in TSR. This is suggested by the promotion effects of acid-clay minerals including illite and particularly montmorillonite. The basic mineral calcite retards the destruction of n-C9+ normal alkanes within the TSR experiments. Furthermore, clay minerals have a minor influence on the generation of LMW monoaromatics and play a negative role in regulating the concentrations of LMW saturated hydrocarbons; calcite does not favor the generation of LMW monoaromatics and plays a positive role in controlling the concentrations of LMW saturates relative to clay minerals. Quartz has a negligible role in the TSR experiments.Due to their differential responses to TSR, LMW hydrocarbon parameters, such as Schaefer [Schaefer, R.G., Littke, R., 1988. Maturity-related compositional changes in the low-molecular-weight hydrocarbon fraction of Toarcian Shale. Organic Geochemistry 13, 887-892], Thompson [Thompson, K.F.M., 1988. Gas-condensate migration and oil fractionation in deltaic systems. Marine and Petroleum Geology 5, 237-246], Halpern [Halpern, H., 1995. Development and application of light-hydrocarbon-based star diagrams. American Association of Petroleum Geologists Bulletin 79, 801-815] and Mango [Mango, F.D., 1997. The light hydrocarbons in petroleum: a critical review. Organic Geochemistry 26, 417-440] parameters and stable carbon isotopic compositions of individual LMW saturated hydrocarbons in TSR affected oils should be used with caution. In addition, water promotes thermal cracking of n-C9+ normal alkanes and favors the generation of LMW cycloalkanes and monoaromatics. The result is lower concentrations of n-C9+ HMW normal alkanes and higher concentrations of LMW cycloalkanes and monoaromatics in hydrous experiments relative to anhydrous experiments with or without minerals.This investigation provides a better understanding of the effects of TSR on LMW hydrocarbons and the influence of reservoir minerals on TSR in natural systems. The paper shows how LMW hydrocarbon indicators in TSR altered oils improve understanding of the processes of hydrocarbon generation, migration and secondary alteration in subsurface petroleum reservoirs. 相似文献
387.
Characteristics and mechanisms of the upwelling in the southern Taiwan Strait: a three-dimensional numerical model study 总被引:3,自引:0,他引:3
Yuwu?JiangEmail author Fei?Chai Zhenwen?Wan Xin?Zhang Huasheng?Hong 《Journal of Oceanography》2011,67(6):699-708
Using a nested circulation model based on the Princeton Ocean Model, we investigate the characteristics and mechanisms of
two main upwellings in the southern Taiwan Strait: the Southwest upwelling and the Taiwan Bank upwelling. The Southwest upwelling
exists in summer when the southwesterly monsoon dominates, and the Taiwan Bank upwelling occurs over a longer period from
May to September. The upslope current over a distinctly widened shelf transports the cold water on-shoreward at the lower
layer and the southwesterly monsoon wind drives the cold water to the surface layer, forming the Southwest upwelling, while
tidal residual current weakens the upslope advection. For the Taiwan Bank upwelling, the upward transport of the South China
Sea water due to the Bank topography carries the cold water from the subsurface layer to the depth of approximately 25 m near
the Taiwan Bank, then the strong tidal mixing forces this upwelled water further upward to the surface layer. 相似文献
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389.
随着现代科学技术的飞速发展,微机办公自动化的普及,为了提高气象资料的质量,在人工初审的基础上,利用计算机对气象观测数据的检查、判断,找出不合理、不正常的记录,不但提高了业务质量,也减轻了手工预审的工作量。但针对目前的气象测报业务来说,还达不到完全自动化,有一部分仍需人工预审来把关。1对于原始记录的人工预审预审员应该从每一个观测数据开始,初值、器差、订正后的数值,以及数据间的关联,要素间的变化规律,包括各种自记纸的整理,仪器与数据的联系,还有必须熟悉的地面气象观测规范和有关规定以及上级下发各种业务… 相似文献
390.