M. Fytikas, G. E. Vougioukalakis (eds): The South Aegean active volcanic arc: present knowledge and future perspectives
Elsevier, 2005. Developments in Volcanology, v.7. Hardcover, 398 pages, ISBN 10: 0-444-52046-5, ISBN 13: 978-0-444-52046-3, USD 195.00     

Gonca Gen?alio?lu Ku?cu 《Bulletin of Volcanology》2012,74(1):303-304

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Inter-decadal Variability in Phytoplankton Community in the Middle Adriatic (Kaštela Bay) in Relation to the North Atlantic Oscillation     

Živana Ninčević Gladan  Ivona Marasović  Branka Grbec  Sanda Skejić  Mia Bužančić  Grozdan Kušpilić  Slavica Matijević  Frano Matić 《Estuaries and Coasts》2010,33(2):376-383

Evaluation of a 45-year data set of primary production (PP), a 30-year data set of phytoplankton biomass, and a 51-year data set of species composition shows an increase of phytoplankton biomass and abundance in the period from the mid-1980s to the mid-1990s. Phytoplankton biomass showed bimodal seasonal cycles, with winter and spring maxima, which did not change over the past 30 years. Diatoms were the most abundant functional group and they prevailed during the colder part of the year while the dinoflagellate contribution to the phytoplankton community increased in the warmer period from May to August. Diatoms showed a significant negative correlation with sea surface temperature (SST), while dinoflagellates were positively correlated with SST. An increase of phytoplankton abundance, particularly dinoflagellate, in the period from the mid-1980s to the mid-1990s coincided with years characterized by a high North Atlantic Oscillation (NAO) index. Primary production and chlorophyll a concentration in the spring period were negatively correlated with the NAO winter (DJFM) index, probably caused by increased precipitation associated with a low or negative NAO index. PP in winter during the mixing period was positively related to the NAO winter index associated with higher temperatures and dry conditions which brought more clear days and increased input of solar radiation.  相似文献   

Framework for assessing probability of exceeding a specified liquefaction-induced settlement at a given site in a given exposure time     

Chih-Chieh Lu  Jin-Hung Hwang  C. Hsein Juang  Chih-Sheng Ku  Zhe Luo 《Engineering Geology》2009,108(1-2):24-35

This paper presents a framework for assessing the probability of exceeding a specified liquefaction-induced settlement at a given site in a given exposure time. This framework deals not only with the effect of liquefaction (in terms of settlement) but also with probabilistic characterization of all possible ground motions at a given site (in terms of a joint distribution of a_max and M_w). Additionally, a new concept, referred to herein as liquefaction-induced settlement hazard curve, is introduced for assessing the annual rate of settlement exceedance at a given site. This settlement hazard curve concept has the potential to be a very useful tool in the field of geotechnical earthquake engineering. Satisfactory results are obtained in the demonstration examples analyzed with the proposed framework. Whereas the proposed framework is simple and effective, further refinements to this framework, especially on the treatment of epistemic uncertainty, are warranted.  相似文献   

Observations of pulsating X-ray binaries 4U0900-40 and 4U1223-62     

W. H. -M. Ku  R. S. Wolff 《Astrophysics and Space Science》1979,62(2):439-449

A rocket observation of two pulsating X-ray binaries, 4U0900-40 and 4U1223-62, found no evidence for periodic or quasiperiodic behavior on time scales down to 2 ms. Evidence for complex high-energy spectral features and intrapulse variability is presented for 4U0900-40.  相似文献   

渤中坳陷油气包裹体与油气成藏   总被引：12，自引：0，他引：12  

李荣西  金奎励  周雯雯  杨建业 《沉积学报》2001,19(4):605-610

含油气盆地中油气包裹体对油气运移、聚集成藏具有示踪作用。应用油气包裹体统计分析表明渤中坳陷油气运移聚集的主要层位为浅部第三系。其中下第三系砂岩中普遍含有两类油气包裹体,即原生油气包裹体和次生油气包裹体,它们分别记录了研究区两次油气运移、聚集成藏过程。次生油气包裹体个体大、分布广、含量明显高于原生油气包裹体,其主要充填分布在次生溶蚀孔隙和裂隙中。均一温度测量、包裹体成分和生物标志化合物分析结果综合表明,次生油气包裹体记录的第二次油气运移是本区最主要的一次油气聚集成藏过程,其油气来源于下第三系湖相泥质烃源岩。结合地质演化特征分析认为,渤中坳陷目前油气勘探的重点应是浅部下第三系地层,而不是深部其它地层。早第三纪晚期构造运动、沉积间断和次生溶蚀孔隙特征研究,以及与之相关储层预测是本区油气勘探获得突破的关键所在。  相似文献   

Abschätzung der Geometrischen-und Genauigkeitsparameter eines Dreiecknetzes     

Karel Kučera 《Studia Geophysica et Geodaetica》1970,14(4):382-388

Summary Approximate formulae (2,4) were derived for estimating the geometric parameters of a national triangular net, if its area P, in a certain way determined circumference O, and intended average length of the triangle side d are given. The formulae are given for n_Δ triangles, n_b points, n_d sides, and for r_g conditions with a trigonometrical net the bearings of which are measured, or r_l conditions with a trilateral net. Other approximate formulae (7–10) serve for estimating the mean errors M_g and M_l of adjusted observations and the positional errors M_x,y,g and M_x,y,l of the points of the net. Equation (11) gives the relation between the mean errors of observations m_g and m_l, which leads to the same positional accuracy with both bearing and distance measuring methods. The effect of the relative error R_d of the estimate of distance d is only observed with the geometric parameters and it is given by equations (6).

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Anschrift: Politickych vězňů 12, Praha 1-Nové Město.  相似文献   

洞穴石笋的^14C年代学研究——石花洞研究系列之二          下载免费PDF全文

李红春  陈文寄 《地震地质》1996,18(4):329-338

由于受“死碳”的影响,年轻洞穴碳酸盐的＾１４Ｃ测年始终受到限制,为此,建立了＾１４Ｃ法测定石笋生长速率及校正“死碳”影响的理论模式,从而将石笋的测年时限和精度大大提高。这一理论成功地运用于北京石花洞年轻石笋的定年。利用＾１４Ｃ法与石笋生长光性年际纹层推算的平均生长速率十分吻合,表明石笋Ｓ３１２的生长速率为０．０４２ｍｍ／ａ。＾２１０Ｐｂ法测定石笋顶部的年龄小于１００ａ,与＾１４Ｃ结果的外推年龄基本  相似文献   

Gas seepage, pockmarks and mud volcanoes in the near shore of SW Taiwan   总被引：2，自引：0，他引：2  

Song-Chuen Chen  Shu-Kun Hsu  Ching-Hui Tsai  Chia-Yen Ku  Yi-Ching Yeh  Yunshuen Wang 《Marine Geophysical Researches》2010,31(1-2):133-147

In order to understand gas hydrate related seafloor features in the near shore area off SW Taiwan, a deep-towed sidescan sonar and sub-bottom profiler survey was conducted in 2007. Three profiles of high-resolution sub-bottom profiler reveal the existence of five gas seeps (G96, GS1, GS2, GS3 and GS4) and one pockmark (PM) in the study area. Gas seeps and pockmark PM are shown in lines A and C, while no gas venting feature is observed along line B. This is the first time that a gas-hydrate related pockmark structure has been imaged off SW Taiwan. The relatively high backscatter intensity in our sidescan sonar images indicates the existence of authigenic carbonates or chemosynthetic communities on the seafloor. More than 2,000 seafloor photos obtained by a deep-towed camera (TowCam) system confirm the relatively high backscatter intensity of sidescan sonar images related to bacteria mats and authigenic carbonates formation at gas seep G96 and pockmark PM areas. Water column gas flares are observed in sidescan sonar images along lines A and C. Likewise, EK500 echo sounder images display the gas plumes above gas seep G96, pockmark PM and gas seep GS1; the gas plumes heights reach about 150, 100 and 20 m from seafloor, respectively. Based on multichannel seismic reflection (MCS) profiles, an anticline structure trending NNE-SSW is found beneath gas seep G96, pockmark PM and gas seep GS2. It implies that the gas venting features are related to the anticline structure. A thermal fluid may migrate from the anticline structure to the ridge crest, then rises up to the seafloor along faults or fissures. The seafloor characteristics indicate that the gas seep G96 area may be in a transitional stage from the first to second stage of a gas seep self-sealing process, while the pockmark PM area is from the second to final stage. In the pockmark PM area, gas venting is observed at eastern flank but not at the bottom while authigenic carbonates are present underneath the pockmark. It implies that the fluid migration pathways could have been clogged by carbonates at the bottom and the current pathway has shifted to the eastern flank of the pockmark during the gas seep self-sealing process.  相似文献   

Origin of the Zálesí U–Ni–Co–As–Ag/Bi deposit,Bohemian Massif,Czech Republic: fluid inclusion and stable isotope constraints     

Zdeněk Dolníček  Bohuslav Fojt  Walter Prochaska  Jan Kučera  Petr Sulovský 《Mineralium Deposita》2009,44(1):81-97

The Zálesí vein-type deposit is hosted by Early Paleozoic high-grade metamorphic rocks on the northern margin of the Bohemian Massif. The mineralization is composed of three main stages: uraninite, arsenide, and sulfide. The mineral assemblages formed at low temperatures (~80 to 130°C, locally even lower) and low pressures (<100 bars). The salinity of the aqueous hydrothermal fluids (0 to 27 wt.% salts) and their chemical composition vary significantly. Early fluids of the oldest uraninite stage contain a small admixture of a clathrate-forming gas, possibly CO₂. Salinity correlates with oxygen isotope signature of the fluid and suggests mixing of brines [δ ¹⁸O around +2‰ relative to standard mean ocean water (SMOW)] with meteoric waters (δ ¹⁸O around −4‰ SMOW). The fluid is characterized by highly variable halogen ratios (molar Br/Cl = 0.8 × 10⁻³ to 5.3 × 10⁻³; molar I/Cl = 5.7 × 10⁻⁶ to 891 × 10⁻⁶) indicating a dominantly external origin for the brines, i.e., from evaporated seawater, which mixed with iodine-enriched halite dissolution brine. The cationic composition of these fluids indicates extensive interaction of the initial brines with their country rocks, likely associated with leaching of sulfur, carbon, and metals. The brines possibly originated from Permian–Triassic evaporites in the neighboring Polish Basin, infiltrated into the basement during post-Variscan extension and were finally expelled along faults giving rise to the vein-type mineralization. Cenozoic reactivation by low-salinity, low-δ ¹⁸O (around −10‰ SMOW) fluids of mainly meteoric origin resulted in partial replacement of primary uraninite by coffinite-like mineral aggregates.  相似文献   

基于1:100万土壤空间数据库的有机碳储量估算研究——以中国东北三省为例   总被引：3，自引：0，他引：3  

孙维侠  史学正  于东升  王库  王洪杰 《地理科学》2004,24(5):568-572

以最近建成的中国1:100万土壤空间数据库以及《中国土种志》和省级土种志的土壤属性为基础,共收集东北三省736个土壤剖面理化分析数据,估算出该地区土壤有机碳总储量,并分析讨论了土壤有机碳密度在空间上的分布特征。结果表明,东北三省土壤有机碳密度平均为16.13 kg/m²,在空间分布上的总趋势为东北部高,西南部低,密度较高的有机碳主要分布在原始森林、湿地及部分农业耕作区中。土壤有机碳密度最高的土类为泥炭土和沼泽土等土类,最低的为石质土、风沙土等土类。  相似文献