The hydrocarbon generation mechanism and the three-stage type model of hydrocarbon generation for carbonate source rocks   总被引：1，自引：0，他引：1  

Zhaoyun Wang  Keming Cheng 《中国科学D辑(英文版)》1997,40(3):232-238

The diagenetic mechanism and process of carbonate rocks, which is different to that of clastic rocks, decides the existence of different existing state organic matters in carbonate rocks. This has been verified by both the microscopic observation of organic petrology and the analysis of organic geochemistry of many samples. Based on the hydrous pyrolysis simulation experiment of the low-mature carbonate rocks, the contrasting study on the yield and their geochemistry characteristics of different existing state soluble organic matters of a series of various maturity samples shows that the different existing state organic matters make different contributions to hydrocarbon generation during every evolution state. So that, the hydrocarbon generation process of carbonate rocks can be summarized as the following three stages: the first is the direct degradation of biogenic bitumen macromolecules during the immature stage, the second is the thermal degradation of a large amount of kerogen at the mature stage, the last stage is the expulsion or release of inclusion organic matter owing to the increased thermal expansion pressure during the high evolution stage. Part of achievements of the Eighth Five-Year National Science-Technology Key-Task Project “85-102-02-07”.  相似文献   

孕震系统中的1/f噪声行为   总被引：3，自引：1，他引：3       下载免费PDF全文

安镇文  叶正仁 《地球物理学报》1997,40(3):380-385

根据自组织临界现象理论,研究7海城、唐山等7个大地震前、后中小地震的活动特征,计算了不同孕震时期地震活动的功率谱特征.初步结果表明描述地震活动的谱幂律指数p值在大震发生前有明显的增高倾向.主震前一年及主震当年,p值一般落在闪变噪声的谱域,其他时间一般很小.最后讨论了地震孕育的物理过程及孕震系统的稳定性.  相似文献   

山谷冰川稳定态时积累区面积比率研究     

王宁练  薄健辰 《冰川冻土》1997,19(2):167-172

探讨山谷冰川稳定状态时积累区面积比率，即ＡＡＲ值的大小，认为冰川物质平衡高程分布，平面形态及坡面坡度沿程变化形式是影响山谷冰川稳定态ＡＡＲ值的主要因素，并 山谷冰川稳定态ＡＡＲ值与物质平衡高程分布及平面形态之间的定量关系。山谷冰川适合于应用ＡＲ值法来研究古冰川的零平衡线高程。  相似文献   

Frequency domain modal analysis of earthquake input energy to highly damped passive control structures     

Izuru Takewaki 《地震工程与结构动力学》2004,33(5):575-590

A new complex modal analysis‐based method is developed in the frequency domain for efficient computation of the earthquake input energy to a highly damped linear elastic passive control structure. The input energy to the structure during an earthquake is an important measure of seismic demand. Because of generality and applicability to non‐linear structures, the earthquake input energy has usually been computed in the time domain. It is shown here that the formulation of the earthquake input energy in the frequency domain is essential for deriving a bound on the earthquake input energy for a class of ground motions and for understanding the robustness of passively controlled structures to disturbances with various frequency contents. From the viewpoint of computational efficiency, a modal analysis‐based method is developed. The importance of overdamped modes in the energy computation of specific non‐proportionally damped models is demonstrated by comparing the energy transfer functions and the displacement transfer functions. Through numerical examinations for four recorded ground motions, it is shown that the modal analysis‐based method in the frequency domain is very efficient in the computation of the earthquake input energy. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

下辽河平原新近系地下水开采的动态变化特征     

王卫东  宋庆春 《华北地质》2004,27(3):144-148

新近系地下淡水是下辽河三角洲地区的盘锦市和辽河油田主要供水水源。地下水处于封闭到半封闭环境，包括明化镇组(Nm)和馆陶组(Ng)两个含水岩组。天然状态下，地下水位接近或高于地表；开采条件下，地下水位逐年下降，形成区域性降落漏斗，地下水流场均发生显著变化，形成汇向开采区的向心流场。开采明化镇组地下水为主的盘东水源地，开采初期水位下降速率为1.61～5．19m／a，至1996年降至0．63～1．03m／a；馆陶组地下水为主的各水源地，开采初期水位下降速率为2．10～4．21m／a，至1996年减至1．49～2．05m／a。这是由于地下水流场变化，导致明化镇成水体内侵和下移所致，该地地下水中Cl^-的不断增高也证明了这一点。至1998年。平面上，成水体每年增加3．18km^2，盘东水源南部，成水体内侵速率已达每年220m。垂向上成水体年下移速率一般每年0．5～1．67m。进行新近系地下水动态特征和演化趋势研究，将为合理开发利用宝贵的淡水资源提供科学依据。  相似文献   

Nation states, ideological power and globalisation: can geographers catch the boat?     

Martin Jones  Rhys Jones 《Geoforum》2004,35(4):409-424

After a period of considerable and sustained hegemony, many commentators have argued that contemporary processes of globalisation are acting as a challenge to nation state sovereignty. The paper argues that geographers need to focus on the ways in which the nation state continues to act, albeit in a modified manner, within the era of globalisation. This might help to position geography within globalisation debates, which--according to Dicken [Geographers and `globalization': (yet) another missed boat? forthcoming, Transactions of the Institute of British Geographers, 2004]--we have not been centrally involved in. Drawing on the work of Michael Mann, we focus on a neglected dimension of state power--namely, its ideological form--as a means of exploring how the nation state is being differentially re-engineered under globalisation. Using Mann's classification of forms of ideological organisation, we deploy three vignettes in order to demonstrate the evolving nature of ideological power within the contemporary UK State.  相似文献   

Triaxial stress state deep in orogenic belts: an example from Turkey     

T. Masuda  S. Nakayama  N. Kimura  K. Onodera  A. Okamoto 《Journal of Structural Geology》2004,26(12):2203-2209

A rare metachert pebble containing amphibole grains with microboudin structures in a wide range of orientations provides an opportunity to perform stress analysis in two orthogonal orientations on the foliation surface. The sample was analysed by the microboudin method to infer the triaxial stress state during microboudinage. Stress parameters proportional to the far-field differential stress were determined for sodic amphibole grains in the two orientations. The ratio of the stresses in the two orthogonal orientations (σ₁−σ₂)/(σ₁−σ₃) was calculated to be 0.64, indicating that σ₂ lies closer to the midpoint between σ₁ and σ₃ than to σ₃.  相似文献   

宁夏香山荒漠草原区植物群落多样性时空特征   总被引：10，自引：0，他引：10  

尚占环  妙爱兴  龙瑞军  辛明  郭旭生  马文志 《山地学报》2004,22(6):661-668

采用多个多样性指数对宁夏香山荒漠草原区植物群落多样性时间、空间动态进行分析。结果表明，该地区群落时、空动态特征不明显。长期过度放牧导致环境恶化，生境碎化，这些作用的长期性、循环性是造成物种、群落格局与原有时、空动态规律相悖的主要因素，这些因素消除了物种或群落在时间梯度上应有的变化规律。干旱山地物种在长期进化过程中成功的发展了对环境的适应机制，环境的波动性强烈导致了群落多样性在原来消长动态基础上的复杂化，也使多样性动态机制复杂化。应用多种指数数学模型对研究对象进行综合评价，能够真实地反映群落多样性动态。  相似文献   

Regions and sustainable development: regional planning matters   总被引：1，自引：0，他引：1  

Graham Haughton  Dave Counsell 《The Geographical journal》2004,170(2):135-145

This paper looks at how the term 'sustainable development' has been used in the process of regional plan making over the past decade. It emphasizes the differing geographies of these debates within England, in terms of how sustainable development has been used to justify different types of approach in different parts of the country. Both drawing on and challenging recent work on state theory, the paper argues the need to see regional planning as a part of a multi-scalar governance system, whose importance should not be underestimated.  相似文献   

Upper Pleistocene and Holocene paleosalinity and trophic state changes in relation to sea level variation in Rocha Lagoon, southern Uruguay     

F. García-Rodríguez  D. Metzeltin  P. Sprechmann  R. Trettin  G. Stams  L.F. Beltrán-Morales 《Journal of Paleolimnology》2004,32(2):117-135

Paleolimnological data are presented on trophic development in relation to sea level variation in Rocha Lagoon, a 72 km² coastal lagoon in southern Uruguay. Using sediment cores that extended to ∼20,000 yr BP, analyses of grain size, organic matter, carbonate, total carbon, nutrients, and diatoms allowed us to infer changes in trophic state and paleosalinities, which were closely related to Holocene relative sea level variation. Higher trophic states were observed during regressive events, most probably due to increases in runoff and erosion as regressions progressed. Diatom Association Zones (DAZ) were identified in both cores. Those DAZ corresponding to transgressive events were dominated by marine/brackish taxa and relatively low organic matter and nutrient values, while those DAZ corresponding to regressive events showed increases in brackish/freshwater diatoms and both organic matter and nutrients. Although the lagoon formed after the first Holocene marine transgression, our data indicate the existence of a marine/brackish aquatic system during upper Pleistocene (i.e., before 15,000 yr BP), but by ∼20,000 yr BP, the system was still likely to be a semi-arid terrestrial system.  相似文献