两城水源地喀斯特水资源评价     

王延恩  李念国  韩汝钊 《地下水》2003,25(2):103-105

两城水源地具有较丰富的喀斯特水，根据长期观测资料，充分考虑水资源的各种补给和开采条件，应用水均衡原理，对其水资源量进行定量评价，获得允许可开采量，为工农业供水提供可靠依据。  相似文献   

辽河盆地东部凹陷热历史及构造—热演化特征   总被引：9，自引：5，他引：9  

王永新  汪集旸  胡圣标 《地质科学》2003,38(2):214-220

根据辽河盆地东部凹陷大地热流测量和镜质体反射率数据,恢复了该区的热历史,结果表明:东部凹陷热流呈现古热流高现今热流低的变化特征,沙河街组三段沉积期到东营组沉积期(距今43～25Ma)盆地热流为66～82mWm²,现今热流值为47～70mWm²。构造沉降史分析显示,盆地经历了早期的裂谷阶段(距今43～25Ma)和后期的热沉降阶段,裂谷阶段包含了两个裂谷亚旋回。盆地现今较低的大地热流和较高的古热流及典型的裂谷型构造沉降样式为东部凹陷的构造—热演化提供了重要认识。  相似文献   

A high precision U–Pb age of metamorphic rutile in coesite-bearing eclogite from the Dabie Mountains in central China: a new constraint on the cooling history     

Qiuli Li  Shuguang Li  Yong-Fei Zheng  Huimin Li  Hans Joachim Massonne  Qingchen Wang 《Chemical Geology》2003,200(3-4):255-265

This paper first reports a high precision U–Pb age of 218±1.2 Ma for rutile in coesite-bearing eclogite from Jinheqiao in the Dabie Mounteins, east–central China. This work shows that the U–Pb mineral (rutile+omphacite) isochron age of 218±2.5 Ma and conventional rutile U–Pb concordia age of 218±1.2 Ma obtained by common Pb correction based on the Pb isotopic composition of omphacite in the same eclogite sample are consistent, proving that the omphacite with low U/Pb ratio (μ=2.8) can be used for common Pb correction in U–Pb dating of rutile. Oxygen isotope analysis of rutile aliquots gave the consistent δ¹⁸O values of −6.1±0.1%, demonstrating oxygen isotope homogenization in the rutile of different grains as inclusion in garnet and grain in matrix. Oxygen isotope thermometry yields temperatures of 695±35 and 460±15 °C for quartz–garnet and quartz–rutile pairs, respectively. These oxygen isotopic observations suggest that the diffusion of oxygen in rutile as inclusion in garnet is not controlled by garnet. According to field-based thermochronological studies of rutile, an estimate of the T_c of about 460 °C for U–Pb system in rutile under rapid cooling conditions (20 °C/Ma) was advised. Based on this U–Pb age as well as the reported chronological data with their corresponding metamorphic and/or closure temperature, an improved T–t path has been constructed. The T–t path confirms that the UHPM rocks in South Dabie experienced a rapid cooling following the peak metamorphism before 220 Ma and a long isothermal stage from 213 to 180 Ma around 425 °C.  相似文献   

The postglacial history of three Picea species in New England, USA     

Matts Lindbladh  George L Jacobson Jr.Molly Schauffler 《Quaternary Research》2003,59(1):61-69

Given the difficulty of separating the three Picea species—P. glauca, P. mariana, and P. rubens (white, black, and red spruce)—in the pollen record, little is known about their unique histories in eastern North America following deglaciation. Here we report the first use of a classification tree analysis (CART) to distinguish pollen grains of these species. It was successfully applied to fossil pollen from eight sites in Maine and one in Massachusetts. We focused on the late glacial/early Holocene (14,000 to 8000 cal yr B.P.) and the late Holocene (1400 cal yr B.P. to present)—the two key periods since deglaciation when Picea has been abundant in the region. The result shows a shift from a Picea forest of P. glauca and P. mariana in the late glacial to a forest of P. rubens and P. mariana in the late Holocene. The small number of P. rubens grains identified from the late glacial/early Holocene samples (<5%) suggests that that species was either absent or rare at most of the sites. The occurrence and distribution of the three species do not reveal any geographic or temporal trend during late glacial time, but the data suggest that they were distributed in local patches on the landscape. The results of this study indicate that the recent population expansion of Picea (1000 to 500 cal yr B.P.) was likely the first time since deglaciation that P. rubens was abundant in the region.  相似文献   

南京市农业资源开发效益的评估   总被引：10，自引：0，他引：10  

李湘阁  闵庆文 《南京气象学院学报》1997,20(2):231-236

根据南京市农业资源开发的有关资料，参照已有的研究成果，拟定了农业资源开发效益评估的指标体系，确定其仅重分配，分别对农业资源开发后的经济效益，生态效益，社会效益及综合效益进行了评估。所得结果，为南京市农业资源的进一步开发利用提供了依据。  相似文献   

包头市工业资源的生态开发利用与持续发展   总被引：1，自引：0，他引：1  

薛东前 《干旱区地理》1997,20(1):53-56

本文从生态经济和持续发展的观点出发，论述了包头市工业资源的优势与劣势，指出发展的根本出路在于对工业资源的生态开发和持续发展，对工业资源的生态开发和无围绕太 导产业群本进行，文章分别指出农产品加工业，能源工业，材料工业和机械工业的资源生态开发和问题，并提出其共同的指导性措施。  相似文献   

台湾恒春半岛的隆起珊瑚礁台地          下载免费PDF全文

王鑫 《第四纪研究》1997,17(4):327-332

台湾本岛南端的恒春半岛,出露隆起珊瑚礁石灰岩和现代珊瑚礁海岸。隆起珊瑚礁石灰岩在地貌上的表现是多阶的台地。最高的公园面可达海拔300m,依次向下,是海拔约100～160m的笼仔埔面,海拔70～80m的埔顶面以及海拔10～20m的垦丁面。在恒春半岛的西侧,珊瑚礁台地面已经倾斜,因此高度的表现不同。ESR及¹⁴C定年表明,抬升的更新世珊瑚礁台地形成于0.5Ma B.P.前后及0.13Ma B.P.两时期;海拔10～20m的全新世珊瑚礁台地约形成于6 000a B.P.的时期。这些证据显示了地质时期里全球变迁的蛛丝马迹。  相似文献   

超积累植物与找矿   总被引：13，自引：0，他引：13  

唐世荣  黄昌勇  朱祖祥 《物探与化探》1997,21(4):263-268

本文介绍了超积累植物的概念和它在地质找矿中的意义,回顾了国外超积累植物的研究历史,并对应用超积累植物进行找矿的发展方向进行了讨论。  相似文献   

Numerical models of mantle convection with secular cooling     

Wanda DeLandro-Clarke  Gary T. Jarvis 《Geophysical Journal International》1997,129(1):183-193

A 2-D time-dependent finite-difference numerical model is used to investigate the thermal character and evolution of a convecting layer which is cooling as it convects. Two basic cooling modes are considered: in the first, both upper and lower boundaries are cooled at the same rate, while maintaining the same temperature difference across the layer; in the second, the lower boundary temperature decreases with time while the upper boundary temperature is fixed at 0°C. The first cooling mode simulates the effects of internal heating while the second simulates planetary cooling as mantle convection extracts heat from, and thereby cools, the Earth's core. The mathematical analogue between the effects of cooling and internal heating is verified for finite-amplitude convection. It is found that after an initial transient period the central core of a steady but vigorous convection cell cools at a constant rate which is governed by the rate of cooling of the boundaries and the viscosity structure of the layer. For upper-mantle models the transient stage lasts for about 30 per cent of the age of the Earth, while for the whole mantle it lasts for longer than the age of the Earth. Consequently, in our models the bulk cooling of the mantle lags behind the cooling of the core-mantle boundary. Models with temperature-dependent viscosity are found to cool in the same manner as models with depth-dependent viscosity; the rate of cooling is controlled primarily by the horizontally averaged variation of viscosity with depth. If the Earth's mantle cools in a similar fashion, secular cooling of the planet may be insensitive to lateral variations of viscosity.  相似文献   

Book Reviews     

《The Professional geographer》1997,49(2):257-268

Committee on Protection and Management of Pacific Northwest Anadromous Salmonids Upstream: Salmon and Society in the Pacific Northwest Cook, Ian G; Doel, Marcus A. and Li, Rex (eds.) Fragmented Asia: Regional Integration and National Disintegration in Pacific Asia Crush, Jonathan Power of Development de Blij, H. J., and Muller, Peter O. Physical Geography of the Global Environment Hayward, David J. International Trade and Regional Economies: The Impacts of European Integration on the United States Kennedy, Michael The Global Positioning System and GIS: An Introduction Lowe, Philip; Marsden, Terry and Whatmore, Sarah (eds) Regulating Agriculture Marsden, Terry; Lowe, Philip and Whatmore, Sarah (eds) Labour and Locality: Uneven Development and the Rural Labour Process Marsden, Terry; Lowe, Philip and Whatmore, Sarah (eds) Rural Restructuring: Global Processes and Their Responses Whatmore, Sarah; Marsden, Terry and Lowe, Philip (eds) Gender and Rurality Whatmore, Sarah; Marsden, Terry and Lowe, Philip (eds) Rural Enterprise: Shifting Perspectives on Small-Scale Production Martopo, Sugeng and Mitchell, Bruce (eds) Bali: Balancing Environment, Economy and Culture Ould-Mey, Mohameden Global Restructuring and Peripheral States: The Carrot and the Stick in Mauritania Redclift, Michael and Benton, Ted (eds) Social Theory and the Global Environment Thomas–Slayter, Barbara and Rocheleau, Dianne Gender, Environment, and Development in Kenya: A Grassroots Perspective Wallach, Bret Losing Asia: Modernization and the Culture of Development Wennberg, John E. Dartmouth Atlas of Health Care Wilson, David and Huff, James O. (eds) Marginalized Places and Populations: A Structurationist Agenda  相似文献