不同气温与土壤湿度条件下籽蒿幼苗的表型可塑性   总被引：2，自引：2，他引：0  

郭立冬  何兴东 《中国沙漠》2011,30(4):987-991

  植物表型可塑性是其适应环境的结果。为了探讨构件水平和全株水平表型可塑性的差异,我们选择籽蒿进行了双因素(气温:35 ℃、30 ℃、20 ℃; 土壤水分:对照、轻度、中度、重度胁迫)随机化区组实验以分析不同环境条件下植物的表型可塑性。结果表明,气温对籽蒿株高生长率有显著影响,土壤水分胁迫对籽蒿株高生长率无显著影响; 气温和土壤水分胁迫对籽蒿地上部生物量和根重生长率均无显著影响; 土壤水分胁迫对籽蒿幼苗根冠比有显著影响,而气温对其则无显著影响。这说明气温和土壤水分胁迫对籽蒿幼苗构件表型可塑性和全株表型可塑性的影响是有差异的。进一步分析表明,气温对籽蒿幼苗的叶含水量有显著影响,而对籽蒿幼苗的叶饱和亏无显著影响,这说明气温对籽蒿幼苗株高生长率的影响是通过影响其叶含水量来实现。  相似文献   

Deformation temperatures and flow vorticities near the base of the Greater Himalayan Series,Sutlej Valley and Shimla Klippe,NW India     

《Journal of Structural Geology》2013

We report new deformation temperature and flow vorticity data from the base of the Greater Himalayan Series (GHS) exposed in the Sutlej Valley and Shimla Klippe of NW India. We focus on three groups of transects across the hanging wall of the Main Central Thrust (MCT). In order of relative foreland – hinterland positions, they are the Shimla Klippe, Western and Eastern Sutlej transects. Deformation temperatures indicated by quartz c-axis fabric opening-angles increase both from foreland to hinterland at a given structural distance above the MCT and up structural section from the MCT within individual transects. Deformation temperatures in the immediate hanging wall to the MCT are estimated at ∼510–535, 535–550 and 610 °C on the Shimla, Western Sutlej and Eastern Sutlej transects, respectively. The steepest inferred field gradients in deformation temperatures are recorded adjacent to the MCT and progressively decrease up structural section following a power law relationship. Comparison with temperature estimates based on multi-mineral phase equilibria data suggests that penetrative shearing occurred at close to peak metamorphic conditions. Vorticity analyses indicate that shearing along the base of the GHS occurred under sub-simple shear conditions (Wm values of 0.9–1.0) with a minor component of pure shear.  相似文献   

Strain rates at high temporal resolution from curved inclusion trails in garnet,Passo del Sole,Central Swiss Alps   总被引：1，自引：0，他引：1  

W. D. CARLSON  J. N. CONNELLY 《Journal of Metamorphic Geology》2013,31(3):243-262

Quantitative strain rates at outcrop scale are very difficult to obtain, but they may be estimated from crystals with curved inclusion trails by calculating rotation rates from growth rates and corresponding deflections of the internal foliation. Garnet in a quartzose pelite at Passo del Sole in the central Swiss Alps is extraordinarily valuable for calculation of strain rates during Alpine orogenesis, because the unusual zoning patterns clearly define the kinetics of its nucleation and growth. Complex concentric zoning patterns can be correlated from one crystal to another in a hand sample, based on compositional and microstructural similarities; the ubiquity of these features demonstrates that all garnet crystals nucleated at nearly the same time. Compositional bands whose radial widths are proportional to crystal size provide evidence for growth governed by the kinetics of intergranular diffusion of locally sourced nutrients. Together, these constraints increase the reliability of estimates of rates of garnet growth, and the strain‐rate calculations that depend on them. To obtain growth rates, P–T conditions during garnet crystallization were modelled in a series of pseudosections, and compositional evolution was connected to rates of garnet growth by means of an independently determined heating rate. These growth rates, combined with measured amounts of curvature of inclusion trails, indicate that the time‐averaged strain rate at Passo del Sole during Alpine metamorphism was on the order of 10^?14 s^?1. Strain rates calculated using rotational v. non‐rotational models are similar in magnitude. The constraints on crystallization kinetics also allow direct calculation of strain rates during individual stages of garnet growth, revealing short‐term increases to values on the order of 10^?13 s^?1. These higher strain rates are correlated with the growth of concentric high‐Ca or high‐Mn zones in garnet, which implies that strain softening associated with the transient passage of fluids is responsible for acceleration of deformation during these intervals.  相似文献   

Effects of fault activities on hydrocarbon migration and accumulation in the Zhu I Depression,Pearl River Mouth Basin,South China Sea     

H. Jiang  H. Shi  L. Liu  J. Bai  S. Zou 《Australian Journal of Earth Sciences》2013,60(6):775-788

Faults can act as either conduits or barriers for hydrocarbon migration, because they have complicated anisotropic flow properties owing to their complicated three-dimensional structures. This study focuses on the Zhu I Depression, Pearl River Mouth Basin (PRMB), China. In this area, hydrocarbon migration and accumulation occurred over a relatively short period of time and were contemporaneous with fault activation, so the characteristics of hydrocarbon accumulations can be used to deduce the effect of active faults on hydrocarbon migration and accumulation. This study addresses the effect of fault activity on flow properties during hydrocarbon migration through a quantitative and comparative analysis of fault activity vs hydrocarbon accumulation. The fault slip rate and shale smear factor parameters were used to characterise faulting and elucidate its effect on hydrocarbon migration and accumulation. Active faults are generally excellent vertical conduits with strong fault activation resulting in vertical migration of most hydrocarbons and little preservation; traps near faults with fault slip rates greater than 20 m/Ma rarely contain commercial oil and gas accumulations. Faulting can form shale smear, which, if continuous, can act as a barrier to hydrocarbon migration. An active fault can allow hydrocarbon transport from deeper formations and to be trapped by continuous shale smear in shallower strata. Most of the oil and gas in the Zhu I Depression have accumulated near faults with a moderate fault slip rate (<20 m/Ma) and development of continuous shale smear (SSF<4–6).  相似文献   

辽宁省海岸带主要河口区一万年来沉积速率及海平面波动情况   总被引：1，自引：0，他引：1  

邴智武  陈曦  赵旭  赵岩 《地质与资源》2013,22(5):383-387

采用钻探手段,通过14C、OSL测年,利用4孔岩心,计算了辽宁省海岸带主要河口区一万年来沉积速率,并分析了海平面波动情况.研究表明,辽宁海岸带长期平均的河口海岸区的沉积速率较低.其中,辽东半岛东北部黄海海岸带鸭绿江平原全新世早期处于剥蚀环境,大洋河平原全新世平均沉积速率为1.4 mm/a,辽东湾北部下辽河平原全新世平均沉积速率为1.52 mm/a,辽西海岸带大凌河冲积扇全新世平均沉积速率为1.87mm/a.全新世Ⅰ海相层或海陆过渡相层总体上表现为一次海侵,与下辽河平原区盘山海侵相对应,但各地段海平面波动情况不尽一致.  相似文献   

Determination of passive earth pressure with lower bound finite elements limit analysis and modified pseudo-dynamic method     

《Geomechanics and Geoengineering》2013,8(3):218-229

ABSTRACT

The present study deals with the determination of passive earth pressure under seismic condition by following the lower bound finite elements limit analysis and modified pseudo-dynamic methodology. In accordance with the lower bound finite elements formulation, the stress field was modelled using a three-noded triangular elements, while the passive pressure was determined via linear optimisation. The parametric study was performed, for a vertical rigid retaining wall, by varying the magnitude of seismic acceleration in horizontal direction (k_h) between 0 and 0.3, while the vertical seismic acceleration (k_v) was kept equal to 0 or 0.5 k_h. Furthermore, the damping coefficient for dry cohesionless backfill was kept ξ = 10%. The obtained results in various cases were found to be in good agreement with those found in the literature. It is expected that this method can be further used for solving other important geotechnical stability problems.  相似文献   

铀矿山废石堆表面氡析出率的变化规律   总被引：1，自引：0，他引：1  

刘成  杨亚新  彭道峰  张叶 《华东地质学院学报》2013,(4):385-389

铀矿的退役处理是放射性固体废物处理的一个重要领域,研究退役铀矿的放射性水平及其影响因素具有重要的意义。对某矿山的11个废石堆进行表面氡析出率的实地测量,探讨废石堆表面氡析出率的影响变化规律,提出平地堆放型较依山堆放型的析出率高且更不稳定,建立了废石的粒度大小、在堆表面所处的位置和废石中u,Ra的活度与表面氡析出率的相关性,并建立了表面氡析出率与气温、地温、气压、相对湿度、降雨等气象因素的相关规律,为铀矿山退役治理提供理论依据。  相似文献   

北京地区地闪活动时空分布特征     

梁丽  庞文静  雷勇  王志超  梁存 《气象科学》2019,39(4):515-523

基于国家雷电定位网2010—2014年雷电定位数据和2010—2013年地面气象资料,分析了北京地区各季地闪活动时空分布特征及其与降水量的关系。结果表明,北京地区雷电活动具有明显的日变化特征;雷电发生频次随季节变化明显,负闪和全地闪在秋季变化幅度最大;雷电发生频次最大值和最小值出现时间随季节变化,春季、夏季日循环峰值出现时间在22∶00—23∶00(北京时间),秋季日循环峰值出现时间在01∶00,冬季则为15∶00且不具有显著性;从空间分布上看,可以看出雷电活动分布具有局地性特征,北京地区雷电活动最频繁的地区集中在密云县和平谷区的迎风坡一带、通州区与市辖区交界处,高雷暴日区域位于延庆县、昌平区和平谷西部,延庆县和怀柔区的北部及房山区和门头沟交界处的西部,雷暴发生频次和雷暴日空间分布不完全吻合。通过各季雷电发生频次日变化序列的谐波分析可知,日循环为日变化的主要信号。春季、夏季、秋季雷电发生频次和降水量两者整体变化趋势一致,降水量较雷电发生频次变化缓慢。  相似文献   

沙尘天气下输沙率的野外观测与分析     

康永德  杨兴华  霍文  杨帆  何清  艾力.买买提明 《沙漠与绿洲气象(新疆气象)》2019,13(1):63-69

2014年7月—2014年8月借助风速仪、微梯度集沙仪,通过野外监测系统获取的试验数据,对塔中地区2014年7月—2014年8月沙尘天气过程中贴地层输沙率进行分析,得出:0～85 mm高度内,随着风速的增大,35～85 mm无论是绝对的输沙量还是相对的输沙量都减少。0～85 mm高度内,各层输沙率最大值均出现在风速为8 m·s-1左右,波动较为显著;最小值出现在6.5 m·s-1左右,波动不明显;沙尘天气中,输沙率最大值出现在5～15 mm高度,最小值出现在35～85 mm高度。扬沙天气中,风速9.2 m·s-1时,输沙率最大值在0～5 mm处。沙尘暴天气,拐点风速为7.5 m·s-1,7.5 m·s-1时,输沙率增加不显著,7.5 m·s-1时,输沙率增加显著。通过微梯度集沙仪获得的上述试验数据是风沙工程设计的一个极重要工程参数,具有重要的实践意义。  相似文献   

Flow and deformation failure of sandy slopes   总被引：2，自引：0，他引：2  

G. Biondi  E. Cascone  M. Maugeri 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):1103-1114

The effects of earthquake induced pore pressure on seismic and post seismic stability conditions of cohesionless slopes are investigated with reference to the infinite slope scheme. In cohesionless slopes the shear strength reduction caused by pore pressure build-up may lead the slope to a deformation failure or to a flow failure if liquefaction conditions are approached. Two critical values of the seismic induced pore pressure ratio are introduced to evaluate the effect of shear strength reduction on the slope failure mechanism. The results are given in the form of stability charts and a procedure for the evaluation of the seismic stability condition is described. The procedure gives useful information about the failure mechanism that slopes may exhibit and the displacement analysis which should be carried out.  相似文献