2004年12月26日苏门答腊—安达曼地震激发的地球自由振荡   总被引：1，自引：0，他引：1  

J.PARK  T.-R.A.SONG  J.TROMP  E.OKAL  S.STEIN  G.ROULT  E.CLEVEDE  G.LASKE  H.KANAMORI  P.DAVIS  J.BERGER  C.BRAITENBERG  M.V.CAMP  S.ROSAT  武敏捷 《世界地震译丛》2005,(6):24-31

根据300~500S的面波估计得到的哈佛大学矩心矩张量断层机制,当周期大于1000S时,地球的地震自由振荡的振幅将异常地大。我们对一个比较陡的断层应用根据地震的体波和面波得到的更真实的破裂模型,估计了自由振荡的振幅近似等于地震矩(6.5×1022N.M),这相当于矩震级为9.15。由于破裂的持续时间达600S,故断层破裂模型足以描述地震的观测结果,但却低估了大地测量位移,这些位移表明在尼科巴群岛和安达曼群岛下面发生了缓慢的断层运动。  相似文献   

General Aspects and Resource Potential of Uranium Deposits in China     

LI Ziying  ZHANG Jindai  CAI Yuqi  GUO Q. Y.  ZHU P. F. 《《地质学报》英文版》2014,88(Z2):1371-1372

Please?refer?to?the?attachment(s)?for?more?details.  相似文献   

煤矿地质成图中多边形快速生成算法   总被引：1，自引：0，他引：1  

贾庆仁  车德福  修春华 《测绘科学》2016,41(12):70-74

针对煤矿地质成图中左转算法生成多边形在复杂的二维图形条件下应用效率低的问题,该文提出了一种新的基于左转算法的多边形快速选取及自动生成算法,实现了2D图形环境中多边形的快速选取及自动生成。通过在进行多边形选取时的起始点,起始方向的选择和对悬挂点、线进行处理,解决了复杂图形下多边形选取及自动生成过程中存在的重复生成、效率低下和搜索回退问题。基于GeoMS3D实现该算法,实验结果表明:该算法逻辑简单、结构清晰,在实际的应用中表现出了较高的运算效率。  相似文献   

The Timing of the Palaeoproterozoic Great Oxidation Event using Dykes,Sills and Bolcanics of the Ongeluk Large Igneous Province,Kaapvaal Craton     

Ashley P. GUMSLEY  Kevin R. CHAMBERLAIN  Wouter BLEEKER  Ulf S?DERLUND  Michiel O. DE KOCK  Tobias C. KAMPMANN  Emilie R. LARSSON  Andrey BEKKER 《《地质学报》英文版》2016,90(Z1):67-68

正The Neoarchaean to Palaeoproterozoic Transvaal Supergroup of the Kaapvaal Craton,southern Africa,is one of the best-preserved and most complete stratigraphic records across a critical in juncture in the Earth’s history.  相似文献   

Is maturity index an efficient tool to assess the effects of the physical disturbance on the marine nematode assemblages?—A critical interpretation of disturbance-induced maturity successions in some study cases in Maldives     

SEMPRUCCI F.  COLANTONI P.  BALSAMO M. 《海洋学报(英文版)》2016,35(4):89-98

Maturity index(MI), based on nematode life strategies, has been proposed in 1990 to assess the possible variations of the terrestrial and freshwater nematode assemblages induced by anthropogenic activities. It was subsequently applied also to marine ecosystems and, even if comparatively not yet very popular, it offers a good method to assess the ecological quality in relation to a wide range of anthropogenic drivers. However, few data are available on its response to physical stress, a key factor especially in the coastal areas. In this study, marine nematode genera from two study cases carried out in Maldives are used to test both MI and life strategy traits(i.e., c-p classes) for detecting the effects of physical disturbance. The results confirm that nematodes are well adapted to physical stress showing a general high rate of recovery. C-p scaling and MI did not seem to be appropriate for revealing this disturbance type probably because there are no empirical evidences on the life strategy of several genera, and a possible differential response to various disturbance types may be hypothesized.  相似文献   

The Mesoproterozoic to early Neoproterozoic passive margin Lajeado Group and Apiaí Gabbro,Southeastern Brazil     

G.A.C.Campanha  M.S.Basei  F.M.Faleiros  A.P.Nutman 《地学前缘(英文版)》2016,7(4):683-694

The Lajeado Group in the Ribeira Belt,southeastern Brazil,corresponds to an open-sea carbonate platform,comprised of seven overlapping siliciclastic and carbonatic formations,intruded in its upper portion by the Apiai Gabbro.These rocks have a Neoproterozoic tectonometamorphic overprint related to arc magmatism and the Brasiliano collisional orogeny.Geochronological constraints are given by new UPb SHRIMP and LA-ICP-MS data for Lajeado Group detrital zircons and for magmatic zircons from the Apiai Gabbro.The youngest detrital zircons in the Lajeado Group are 1400-1200 Ma,and constrain its maximum age of deposition to be 1200 Ma,whereas the 877 ± 8 Ma age for magmatic zircons in the Apiai Gabbro give the minimum age.Detritus source areas are mainly Paleoproterozoic(2200-1800 Ma)with some Archean and Mesoproterozoic contribution(1500-1200 Ma),with distal or tectonic stable cratonic character.The Lajeado Group should be a Stenian-Tonian carbonate platform passive margin of a continent at this time,namely the Columbia/Nuna or the Rodinia.The Apiai Gabbro displays similar age to other intrusive basic rocks in the Lajeado and Itaiacoca groups and represents tholeiitic MORB-like magmatism that we relate to the initial break-up of a Mesoproterozoic continent and the formation of the Brasiliano oceans.  相似文献   

The development of the subduction channel and “turning on” of slab-to-mantle material exchanges at the start of subduction: insights from eruptive serpentinites (IODP Exp 366) from the forearc of the Mariana subduction system     

Jeffrey G. Ryan  Raymond Johnston  P. Fryer  C.G. Wheat  T. Williams 《《地质学报》英文版》2018,92(Z1):167-167

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Slab behavior beneath Eastern Asia from full waveform tomography     

Stephen P. Gran  Kai Tao  Fenglin Niu 《《地质学报》英文版》2018,92(Z1):328-328

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Lead contamination of small cetaceans in European waters--the use of stable isotopes for identifying the sources of lead exposure     

Caurant F  Aubail A  Lahaye V  Van Canneyt O  Rogan E  López A  Addink M  Churlaud C  Robert M  Bustamante P 《Marine environmental research》2006,62(2):131-148

Lead concentrations and isotopic composition have been measured in bone and teeth of small cetaceans belonging to three species (Delphinus delphis, Phocoena phocoena and Stenella coeruleoalba), to evaluate the toxicological risk and to determine sources of lead in the European waters. Lead concentrations, far lower than threshold value inducing toxic effects in human, were higher in teeth than in bones, but highly correlated between the two tissues (r=0.92, p<0.001). Large variations of 206Pb/207Pb values in bone tissue showed that cetaceans must be submitted to various atmospheric influences. No geographical differences appeared which is consistent with studies on their distribution indicating seasonal movements between Brittany waters and the Bay of Biscay. The negative correlation between 206Pb/207Pb ratios and age of the individuals reflected the decrease in the production of alkyl lead in Europe, i.e., the increasing use of unleaded gasoline.  相似文献   

Effects of cadmium, zinc and nitrogen status on non-protein thiols in the macroalgae Enteromorpha spp. from the Scheldt Estuary (SW Netherlands, Belgium) and Thermaikos Gulf (N Aegean Sea, Greece)     

Malea P  Rijstenbil JW  Haritonidis S 《Marine environmental research》2006,62(1):45-60

Enteromorpha prolifera (Scheldt Estuary) and E. linza (Thermaikos Gulf) were incubated at three salinities with 100 and 200microgL(-1)Cd and Zn. The objective was to measure effects of Cd, Zn and nitrogen (N) status on the pools of metal-binding non-protein thiols: glutathione and phytochelatins, (gamma-glutamyl-cysteinyl)(n)-glycine (PC). In E. linza, ammonium pools were higher, but amino acid pools, total N and protein contents were lower than in E. prolifera. Reduced glutathione (GSH) pools were positively correlated with free glutamate and protein contents. In E. linza GSH pools increased and the ratio of reduced to oxidized glutathione (GSH:(GSH+0.5GSSG)), an indicator of oxidative stress, decreased with Cd contents, indicating Cd-induced glutathione oxidation. Total glutathione pools (reduced plus oxidized) ranged from 16nmolSgdwt(-1) in controls (at 0.5micromolCdgdwt(-1)) to 179nmolSgdwt(-1) (at 1.9micromolCdgdwt(-1)) at the highest cadmium dosage. Cadmium stimulated PC synthesis in E. prolifera which suggests that in N-rich algae, glutathione pools were high enough for PC synthesis. In both species GSH and protein increased with Zn contents, whereas GSH:(GSH+0.5GSSG) decreased, which would indicate Zn-induced oxidative stress; in E. linza, at the highest salinity the glutathione redox ratio decreased from 0.61 (at 2.9micromolZngdwt(-1)) to 0.26 (at 4.9nmolSgdwt(-1)) (at 0.5molCdgdwt(-1)). PCs were not synthesized in response to Zn, which may have resulted in Zn-induced GSH oxidation. The presence of both oxidative effects (Cd, Zn) and detoxification (Cd) could be identified by observing the responses of glutathione and PC pools to metal stress.  相似文献