21世纪地球科学研究的重大科学问题   总被引：2，自引：1，他引：1  

郑军卫  张志强  赵纪东 《地球科学进展》2008,23(12):1260-1267

凝炼地球科学研究的重大科学问题,对推动地球科学基础研究的发展具有重要意义。美国国家研究理事会（National Research Council）2008年3月发布的研究报告《地球的起源和演化：变化行星的研究问题》提出了21世纪固体地球科学研究的10个重大科学问题：①地球和其他行星的起源;②地球早期的演化历史;③生命的起源;④地球内部的运动及其对地表的影响;⑤地球的板块构造与大陆;⑥地球的物质特性对地球过程的控制;⑦气候变化的原因与幅度;⑧地球—生命的相互作用;⑨地震、火山喷发等灾害及其后果的预测;⑩地球内外流体运动对人类环境的影响。这些重大科学问题对我国的地学发展战略研究及地球科学基础研究均将具有重要的借鉴和指导意义。主要依据NRC的《地球的起源和演化：变化行星的研究问题》报告,对这些重大科学问题进行了解读和分析。  相似文献   

主题性旅游协作联盟及其构建——以运河文化主题协作联盟为例   总被引：5，自引：1，他引：4  

沈山  沈正平  孙旭芳  马晓冬  安宇 《地理研究》2008,27(6):1444-1454

主题性旅游协作联盟是一种新型的旅游合作战略模式,其协作基础为相似的空间认知要素、现代化的信息技术支撑和物态化的整合营销品牌。在分析国内外20多个旅游协作联盟的基础上,从地域联系、主题类型、空间结构和组织形式等4个视角,总结了主题性旅游协作联盟的12种基本类型,指出协作的基础理论是注意力经济学、协作网络共生理论和旅游产业集群理论。选取江苏扬州至山东济宁段运河为研究区域,分析其文化资源和旅游发展状况,提出"千年运河,世纪风情"的运河文化主题,从组织体系、品牌营销、产品体系、保障机制、信息平台等5个方面进行主题性旅游协作联盟的构建。  相似文献   

Vegetation and Climate Reconstruction of the Planalto in Rio Grande do Sul, South Brazil (Late Glacial and Holocene)     

M.Herrmann  A.R.Ashraf  V.Mosbrugger  M.M.Toigo 《世界地质(英文版)》2003,6(2)

A 405 cm long core was drilled in the Aparados da Serra National Park (Rio Grande do Sul, Brazil) at the end of 1999, and in all, 23 samples were taken for palynological investigation. The cores′ age is estimated at 27 000 a BP based on three radiocarbon dates taken from different depths of the core. Palynological methods were used to reconglacial conditions mainly influenced by the South Pole throughout several transition stages to today's humid warm climate, mainly being influenced by the Brazil stream.  相似文献   

Salt tectonics,a controlling factor on the development of the Marseilles and Grand-Rhone sedimentary ridges,Gulf of Lions,western Mediterranean Sea     

Antonio Tadeu dos Reis  Christian Gorini  Alain Mauffret  Wiktor Weibull 《Comptes Rendus Geoscience》2004,336(2):143-150

The Marseilles (also called Marseilles/Planier) and Grand Rhone sedimentary ridges, offshore the Gulf of Lions, western Mediterranean Sea, are generated by sediment spillover funnelled by the Marseilles and Grand-Rhone canyons, respectively. We show that the Marseilles and Grand-Rhone canyon directions are tectonically conditioned by Plio-Quaternary salt-induced sea-floor relief. Overburden extension in the area created an assemblage of listric faults running parallel to the strike of the continental margin. This salt-induced topography resulted in accentuated fault scarps impacting the sea-floor morphology and forcing submarine valleys to deflect to the east. Gravity-induced extension equally influenced the morphological pattern of the valley overbanking deposits. Sediment spillover occurred on both flanks of the canyons, but because active faulting generated space accommodation for overflow deposits, it inhibited the development of typical levee morphology along the canyons' left flanks. To cite this article: A.T. dos Reis, C. R. Geoscience 336 (2004).  相似文献   

金口大峡谷地貌成因与旅游资源   总被引：7，自引：0，他引：7  

罗成德 《山地学报》2004,22(1):30-35

金口大峡谷位于大渡河下游，主要支谷有8条，皆以嶂谷地貌为特色。与大峡谷相邻的大瓦山(3236m)为我国最高的桌状山。这一区域以喀斯特地貌为主，受新构造运动影响明显，具有丰富的旅游地貌资源。  相似文献   

Paleomagnetism of Middle Proterozoic mafic intrusions and Upper Proterozoic (Nankoweap) red beds from the Lower Grand Canyon Supergroup, Arizona     

Arlo B. Weil  John W. Geissman  Matt Heizler  Rob Van der Voo 《Tectonophysics》2003,375(1-4):199

Paleomagnetic data from lavas and dikes of the Unkar igneous suite (16 sites) and sedimentary rocks of the Nankoweap Formation (7 sites), Grand Canyon Supergroup (GCSG), Arizona, provide two primary paleomagnetic poles for Laurentia for the latest Middle Proterozoic (ca. 1090 Ma) at 32°N, 185°E (dp=6.8°, DM=9.3°) and early Late Proterozoic (ca. 850–900 Ma) at 10°S, 163°E (dp=3.5°, DM=7.0°). A new ⁴⁰Ar/³⁹Ar age determination from an Unkar dike gives an interpreted intrusion age of about 1090 Ma, similar to previously reported geochronologic data for the Cardenas Basalts and associated intrusions. The paleomagnetic data show no evidence of any younger, middle Late Proterozoic tectonothermal event such as has been revealed in previous geochronologic studies of the Unkar igneous suite. The pole position for the Unkar Group Cardenas Basalts and related intrusions is in good agreement with other ca. 1100 Ma paleomagnetic poles from the Keweenawan midcontinent rift deposits and other SW Laurentia diabase intrusions. The close agreement in age and position of the Unkar intrusion (UI) pole with poles derived from rift related rocks from elsewhere in Laurentia indicates that mafic magmatism was essentially synchronous and widespread throughout Laurentia at ca. 1100 Ma, suggesting a large-scale continental magmatic event. The pole position for the Nankoweap Formation, which plots south of the Unkar mafic rocks, is consistent with a younger age of deposition, at about 900 to 850 Ma, than had previously been proposed. Consequently, the inferred 200 Ma difference in age between the Cardenas Basalts and overlying Nankoweap Formation provides evidence for a third major unconformity within the Grand Canyon sequence.  相似文献   

Formation and water environmental evolution of the Nansihu Lake     

ZHANG Zulu  SHEN Ji  LIU Enfeng  SUN Qingyi  JIANG Luguang  WANG Lin 《地理学报》2003,13(2):241-249

Through high-resolution research of sedimental chronology and the sediment environmental indexes, such as graininess, minerals, magnetic parameters, pigment content, organic carbon and chronology in Ds-core and Ws-core in Nansihu Lake, the authors analyze the formation cause of the Nansihu Lake and its water environmental changes. Historical documents are also analyzed here in order to reach the conclusion. Researches indicate that the Nansihu Lake came into being about 2500 aBP and its evolution succession can be divided into four stages. In this evolution process, several scattered lakes merge into one large lake in the east of China. This process is distinctively affected by the overflow of the Yellow River, the excavation of the Grand Canal and other human activities.  相似文献   

The Goli d’Aget Member: Early Permian volcanoclastic and volcanic rocks within the Brian?onnais Grand St-Bernard Nappe (Valais, Switzerland)     

Marc-Henri Derron  Jér?me Jacquod  Mario Sartori 《Eclogae Geologicae Helvetiae》2006,99(3):301-307

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Hepatic 7-ethoxyresorufin O-deethylase activity in eel (Anguilla anguilla) from the Thames Estuary and comparisons with other United Kingdom Estuaries     

Doyotte A  Mitchelmore CL  Ronisz D  McEvoy J  Livingstone DR  Peters LD 《Marine pollution bulletin》2001,42(12):1313-1322

Hepatic microsomal 7-ethoxyresorufin O-deethylase (EROD) activities (indicative of exposure to polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBs)) were measured in eel Anguilla anguilla from the Thames Estuary. Fish were collected from up to 13 sites during November 1997, May and August 1998 and October 1999. Throughout this period no clear seasonal variation could be identified at every site along the Thames. However, during the summer months, fish sampled from sites in the middle to the upper estuary (Woolwich, Greenhithe and West Thurrock) reported up to 3-fold higher EROD activities compared to sites either at the upper reaches (Richmond and Brentford) at the same time of the year, or fish sampled in winter, along the entire length of the estuary. A laboratory exposure experiment demonstrated a 3-fold elevation of EROD activity 2 days after injection with β-naphthoflavone (β-NF). However, higher levels of activity could be determined in fish sampled from the Weston canal near the Merseyside. The lowest levels of A. anguilla EROD activity were observed in fish sampled from the upper reaches of the River Tamar, Devon, and were comparable to activities determined in fish from the Wear and Humber estuaries. A. anguilla sampled along the Thames, Tyne and Tees estuaries reported between 2.5- and 7-fold higher EROD activities compared to fish collected from the Tamar. These results indicate that a low to moderate induction of A. anguilla CYP1A had occurred (indicative of low to moderate exposure to PAHs and planar PCBs) in fish collected from the Thames, Tyne, Wear, Tees, Humber and Tamar estuaries. However, the highest level of EROD activity was observed in fish from the Weston Canal (Merseyside).  相似文献   

Was Grand Banks event of 1929 a slump spreading in two directions?     

M. D. Trifunac  A. Hayir  M. I. Todorovska 《Soil Dynamics and Earthquake Engineering》2002,22(5)

This paper describes a kinematic model of tsunami generated by submarine slides and slumps spreading in two orthogonal directions. This model is a generalization of our previously studied models spreading in one direction. We show that focusing and amplification of tsunami amplitudes can occur in an arbitrary direction, determined by the velocities of spreading. This kinematic model is used to interpret the asymmetric distribution of observed tsunami amplitudes following the Grand Banks earthquake—slump of 1929.  相似文献