Earth nutation influence on system dynamics of Northeast Arctic cod   总被引：2，自引：1，他引：1  

Yndestad  H. 《ICES Journal of Marine Science》1999,56(5):652-657

  相似文献   

Tectonic feedback and the earthquake cycle     

Cinna Lomnitz 《Pure and Applied Geophysics》1985,123(5):667-682

The occurrence of cyclical instabilities along plate boundaries at regular intervals suggests that the process of earthquake causation differs in some respects from the model of elastic rebound in its simplest forms. The model of tectonic feedback modifies the concept of this original model in that it provides a physical interaction between the loading rate and the state of strain on the fault. Two examples are developed: (a) Central Chile, and (b) Mexico. The predictions of earthquake hazards for both types of models are compared.  相似文献   

Confluence and intersection of interacting conjugate faults: A new concept based on analogue experiments     

H.-U. Schwarz  F.-W. Kilfitt 《Journal of Structural Geology》2008,30(9):1126-1137

Examination of the interaction area of conjugate faults yields evidence of a yet unknown structural pattern. Analogue experiments revealed the evolution of this pattern during the interaction process. A fault propagating towards the highly active section of another conjugate fault becomes increasingly deflected towards the obtuse angle side of the conjugate system while approaching until joining it. During this process, the tip of the curved propagating fault retains its shear sense until immediately before joining with the highly active fault—a process called “confluence” in this report. Under constant remote stress, the deflected fault now becomes dominant. A fault branch splits off at the point where deflection commences, propagating straight ahead of the original direction, and may dissect the former master fault. Alternating activity at both of the faults finally produces the known intersection patterns. Further studies of the proposed concept on natural examples are recommended due to the close geometric similarity of the evolutionary structural stages and natural fault patterns.  相似文献   

Development of carbonate platforms on an extensional (rifted) margin: the Valanginian–Albian record of the Prebetic of Alicante (SE Spain)   总被引：1，自引：1，他引：0  

J.M. Castro  G.A. de Gea  P.A. Ruiz-Ortiz  L.M. Nieto 《Cretaceous Research》2008,29(5-6):848

Within the upper Valanginian to upper Albian deposits of the easternmost part of the Prebetic Zone of the Betic Cordillera (Iberian Peninsula), seven lithostratigraphic formations made up of shallow-water carbonate and carbonate-siliciclastic sediments and of outer-platform hemipelagic sediments have been recognized. These formations were deposited in the most distal part of a platform that developed on the Southern Iberian Continental Palaeomargin. The geodynamic context was a margin affected by extensional or transtensional faults that produced tilted blocks. The interval studied records three major second-order transgressive-regressive facies cycles: (I) A late Valanginian to earliest Aptian cycle, mostly represented by hemipelagic and condensed sedimentation, with the development of a tectonically controlled high without sedimentation that separated two sectors with different sedimentary evolution and that ended with an episode of shallow-water carbonate platform development; (II) An earliest to latest Aptian cycle, with a transgressive phase represented by a retrogradational shallow-water carbonate platform capped by a drowning event leading to hemipelagic sedimentation, which was affected by an anoxic event (OAE 1a); the regressive phase is represented by progradation and aggradation of shallow-water carbonate deposits. Finally (III) a latest Aptian to early-late Albian cycle that records the expansion of mixed platform deposits in the entire area, ending with a phase of shallow-water carbonate platform development. Extensional tectonics leading to spatial and temporal changes in subsidence patterns is envisaged as the main control on sedimentation at a local scale, resulting in notable lateral changes in thickness as the main signature. Tectonics exerted a strong control on the distribution of sedimentary environments only during Cycle I. At a higher order, sea-level fluctuations are responsible for sequential organization, and environmental factors determined shallow-water carbonate platform development and demise, as well as oceanic anoxic events. The relevant continuity of the stratigraphic record in the distal part of the Prebetic platform has led to the recognition of events related to cycle boundaries, which result mainly from a combination of tectonics and sea-level changes.  相似文献   

Effects of Corn Cob Produced Biochars on Urea Recovery from Human Urine and Their Application as Soil Conditioners          下载免费PDF全文

Yang Zhang  Zifu Li  Ibrahim Babatunde Mahmood 《洁净——土壤、空气、水》2015,43(8):1167-1173

  相似文献   

冻融循环对石灰处置粉质黏土静强度影响研究     

战高峰  张群  朱福  董伟智 《岩土力学》2015,36(Z2):351-356

以吉林－荒岗高速公路沿线的粉质黏土为研究对象,对不同石灰掺入比的土样试件进行0、2、4、6、8、10、12次冻融循环试验。通过室内静三轴试验,研究了冻融循环作用对石灰处置粉质黏土强度的影响。研究结果表明,石灰处置粉质黏土的应力-应变关系曲线呈应变软化型,峰值强度随围压增大而升高,粉质黏土峰值强度降低幅度值比石灰处置粉质黏土峰值强度降低幅度值大,经历4次冻融后应力-应变曲线峰值强度趋于稳定;冻融作用后石灰处置粉质黏土抗剪强度衰减率比粉质黏土的抗剪强度衰减率小,抗剪强度随围压的升高而增大;同一围压条件下石灰处置粉质黏土弹性模量随着冻融次数增加逐渐减小,经历4次冻融后基本趋于稳定。  相似文献   

反复冻融条件下粉砂土动力学参数试验研究     

严晗  王天亮  刘建坤  王扬 《岩土力学》2014,35(3):683-688

在大量冻融试验和动三轴试验的基础上,深入研究和分析了经历多次冻融循环后粉砂土动模量和阻尼比的变化规律。研究结果表明：同一动应变水平下,动应力大小与冻融次数、含水率呈负相关性,而与围压、加载频率、压实度呈正相关性;粉砂土的动应力-动应变关系存在明显的非线性,且随动应变水平的提高,动模量成倍减小,而阻尼比则成倍增大;随冻融次数的增加,动模量降低而阻尼比则增大,且经历6次冻融后均趋于稳定,建议将6次冻融后的力学特性作为设计与计算指标;围压和压实度的提高有效增强了土颗粒之间的骨架作用,动模量随围压和压实度的增减而增减,阻尼比则随围压和压实度的增加而降低;含水率的变化对阻尼比的影响不大,而当土样达到饱和状态时,动模量成倍降低;加载频率对阻尼比的影响较大,并随频率的提高而迅速降低。  相似文献   

中国陆地生态系统通量观测研究网络(ChinaFLUX)的主要进展及发展展望   总被引：5，自引：0，他引：5  

于贵瑞  张雷明  孙晓敏 《地理科学进展》2014,33(7):903-917

基于微气象学理论的涡度相关通量观测技术实现了对生态系统尺度的生产力、能量平衡和温室气体交换等功能和过程的直接测定,特别是全球尺度通量塔观测网络的联合观测是实现从生态现象观察和生态要素观测跨越到全球尺度生态系统功能状态变化观测的重大突破。本文回顾了中国陆地生态系统通量观测研究网络(ChinaFLUX)的创建及发展历程,系统介绍了ChinaFLUX的科学目标和设计理念、观测技术体系、观测数据的标准化处理及长期积累;综合评述了ChinaFLUX在陆地生态系统碳—氮—水的收支评估和交换过程的环境响应、碳通量时空格局及其形成机制等方面所取得的主要研究进展。最后,在探讨未来全球尺度通量塔观测网络发展趋势的基础上,提出了ChinaFLUX的主要发展方向、关键科学问题与未来工作重点,为中国通量观测研究事业的进一步发展提供理论参考。  相似文献   

冻融循环作用下花岗斑岩和灰岩物理力学性质对比分析及应用研究     

闻磊  李夕兵  尹彦波  高栗 《冰川冻土》2014,36(3):632-639

以花岗斑岩和灰岩两种岩性岩石为代表,实验研究了冻融作用下,岩石的致密程度、孔隙率等物理指标对岩石物理力学性质的影响. 通过不同次数的冻融循环实验,对花岗斑岩和灰岩2种典型岩石样本的质量、单轴抗压强度、抗拉强度、冻融系数、风化程度的变化规律进行对比分析,并绘出了冻融次数与试样的抗压强度、抗拉强度、冻融系数的拟合关系曲线. 在一定限定条件下,将实验结果应用于西藏玉龙铜矿花岗斑岩、灰岩边坡的具体实例中,采用强度折减法计算出了矿山边坡冻融风化前、后的安全系数,对比分析了花岗斑岩、灰岩边坡受冻融风化的影响程度,为矿山的设计和施工提供了参考.  相似文献   

Physiological responses of the seagrass Thalassia hemprichii (Ehrenb.) Aschers as indicators of nutrient loading     

Jingping Zhang  Xiaoping Huang  Zhijian Jiang 《Marine pollution bulletin》2014

To select appropriate bioindicators for the evaluation of the influence of nutrients from human activities in a Thalassia hemprichii meadow, environmental variables and plant performance parameters were measured in Xincun Bay, Hainan Island, South China. Nutrient concentrations in the bay decreased along a gradient from west to southeast. Moreover, the nutrients decreased with an increase in the distance from the shore on the southern side of the bay. Among the candidate indicators, the P content of the tissues closely mirrored the two nutrient loading gradients. The epiphytic algae biomass and the N content in the tissues mirrored one of the two nutrient loading trends. The leaf length, however, exhibited a significant negative correlation with the nutrient gradients. We propose that changes in the P content of T. hemprichii, followed by epiphytic algae biomass and N content of the tissues, may be the useful indicators of nutrient loading to coastal ecosystems.  相似文献