鄂尔多斯盆地西南部三叠纪末抬升剥蚀事件及热年代学记录   总被引：1，自引：1，他引：0  

王建强  刘池洋  赵红格  张东东  ZATTIN Massimiliano  彭恒 《岩石学报》2020,36(4):1199-1212

三叠纪末期大型鄂尔多斯盆地遭受了中生代成盆以来首次较大规模的抬升剥蚀,显著改造了中晚三叠世延长期盆地面貌,并控制了侏罗纪早期沉积格局和油藏分布,对盆地演化及矿产资源分布产生了重要影响。本文利用地质及大量钻井资料揭示了该期构造事件对盆地的剥蚀改造特征,盆地及周邻地区磷灰石裂变径迹年代学记录并约束了此次构造抬升的时限与过程;综合周邻区域构造研究成果,探讨了其发育的动力学背景。结果表明,鄂尔多斯盆地三叠纪末期的剥蚀具西南强、东北弱的特点,西南部大范围内延长组地层残缺不全,剥蚀量最大可达1000余米;前侏罗纪沉积古地貌总体呈西南高、北东低的特点;其抬升时间始于205～190Ma,西南部稍早于盆地腹部,抬升速率大于1℃/Myr,可持续至中侏罗世(约160Ma)。该期抬升剥蚀事件范围可涉及至盆地西南缘更广阔的区域,与同期秦岭造山带内出现的快速抬升冷却事件具有较好的时空耦合关系,是对秦岭造山带区域构造环境转变的响应和纪录。该研究丰富和发展了三叠纪末期构造事件在华北克拉通的影响,对该区油气、煤炭资源的进一步勘探和评价提供了新的思路,具有一定的现实意义。  相似文献   

非连续变形分析中块体大转动问题研究     

巩师林  凌道盛  胡成宝  钮家军 《岩土力学》2020,41(11):3810-3822

原有非连续变形分析（DDA）采用一阶近似后的位移增量表达式更新块体构形，推导相关子矩阵，且对不同时步计算出的应变增量直接叠加，当模拟的块体发生大转动时往往会产生较大误差。为考虑块体转动与变形的耦合作用，引入先变形、后转动的块体位移增量表达式。重新推导了惯性力子矩阵，将块体转动时的离心力与科氏力加到荷载矩阵中。计算时对应变分量及其相关变量进行坐标变换与修正，并采用新引入的位移增量表达式计算块体顶点位移，进行后接触修正与更新块体构形。数值算例表明，改进后的程序能够消除转动带来的误差，自动考虑了块体转动时离心力和科氏力引起的变形，应变计算精度更高。改进方法克服了块体体积自由膨胀、应变场畸变等问题，给出了合理的块体应变。  相似文献   

城市地理研究中的单分形、多分形和自仿射分形   总被引：1，自引：0，他引：1  

陈彦光 《地理科学进展》2019,38(1):38-49

分形几何学在城市地理研究中具有广泛的应用,然而很多基本概念却让初学者感到迷惑。如何区分单分形、自仿射分形与多分形,是一个基本而重要的问题。简单分形容易理解,而真实的地理现象很少是单分形的。城市生长过程具有自仿射特征,而城市空间格局却具有多分形性质。作者发现,各种分形的共性在于三个方面：标度律、分数维和熵守恒。论文基于标度、分维和熵守恒公式,借助隐喻城市生长的规则分形来区分单分形、多分形和自仿射分形,讨论分形系统演化的机理、分形与空间自相关和空间异质性的联系,同时澄清一些在地理分形研究中的常见错误概念。最后以城市位序-规模分布为例,说明并对比单分形和多分形在城市地理研究中的建模与应用思路。  相似文献   

浮游植物metacaspase的分布、结构及其功能特性     

苏金净  蔡伟聪  李桂玲  李健  曾珺  刘静雯 《海洋与湖沼》2019,50(5):1059-1069

精氨酸/赖氨酸特异性半胱氨酸蛋白酶(Metacaspase)在浮游植物程序性细胞死亡(programmed cell death.PCD)过程中起着关键作用。本文利用生物信息学方法分析metacaspase基因在浮游植物中的分布,并以海洋球石藻(Emilianiahuxleyi)metacaspases(EhMCs)为代表分析其结构和功能,依据Uniprot和String数据库挖掘与metacaspase功能相关并参与浮游植物PCD过程的互作蛋白。结果发现:共计29条、四种类型的metacaspases分布于11种浮游植物中,它们的metacaspase蛋白一级结构存在明显差异,但位于p20的组氨酸和半胱氨酸活性位点均具有高度的保守性;EhMCs三级结构与酵母的metacaspase十分相似,暗示它们具有类似的功能;浮游植物metacaspases与多种蛋白存在直接或间接的互作关系,在细胞PCD过程、响应环境胁迫和能量代谢等方面发挥重要作用。另外.metacaspase的磷酸化修饰可能在浮游植物PCD信号转导过程中起调节作用。  相似文献   

Experimental study on hydrodynamic performance of SWATH vessels in calm water and in head waves     

《Applied Ocean Research》2019

An extensive experimental investigation on four SWATH hull forms has been conducted in calm water and in regular waves at University of Naples Federico II. Calm water tests have been analyzed in the range of Froude number Fr_T from 0.1 to 0.6. For all four SWATH configurations at the speed, corresponding to Fr_T 0.32, the behaviour in regular waves has been tested. The results of heave, pitch and vertical accelerations are presented in nondimensional form as RAO. For the “most promising” SWATH #4 configuration, a set of stabilizing fins have been designed and an active stabilization system has been developed. The developed SWATH#5 has been tested in calm water on three displacements in the range of Fr_T from 0.1 to 0.65. The dynamic wetted surface has been identified and the residual resistance coefficient C_R as well as R_T/Δ are reported. Seakeeping tests have been performed in regular head sea and in head and following irregular sea at Fr_T = 0.50. The conditions for the occurrence of dynamic longitudinal instabilities have been identified. The results allows to comment the effect of slenderness of struts and SWATH’s immersed bodies on resistance and seakeeping and concerns the applicability of SWATH concept to small craft.  相似文献   

时间尺度重构EEMD-GRNN改进模型预测PM2.5的研究     

符海月  张祎婷 《地球信息科学学报》2019,21(7):1132-1142

合理构建PM_2.5浓度预测模型是科学、准确地预测PM_2.5浓度变化的关键。传统PM_2.5预测EEMD-GRNN模型具有较好的预测精度,但是存在过于关注研究数据本身而忽略其物理意义的不足。本研究基于南京市2014-2017年PM_2.5浓度时间序列数据,分析PM_2.5浓度多尺度变化特征及其对气象因子和大气污染因子的尺度响应,基于时间尺度重构进行EEMD-GRNN模型的改进与实证研究。南京市样本数据PM_2.5浓度变化表现为明显的天际尺度和月际尺度,从重构尺度（天际、月际）构建GRNN模型更具有现实意义;同时,PM_2.5对PM₁₀、NO₂、O₃、RH、MinT等因子存在多尺度响应效应,以其作为GRNN模型中的输入变量更具有时间序列上的解释意义。改进后的EEMD-GRNN模型具有更高的PM_2.5浓度预测精度,MAE、MAPE、RMSE和R²分别为6.17、18.41%、8.32和0.95,而传统EEMD-GRNN模型的模型有效性检验结果分别为8.37、27.56%、11.56、0.91。对于高浓度天（PM_2.5浓度大于100 μg/m³）的预测,改进模型更是全面优于传统EEMD-GRNN模型,MAPE为12.02%,相较于传统模型提高了9.03%。  相似文献   

GRB 170817A的洛伦兹因子和观测角          下载免费PDF全文

林一清 《天文学报》2020,61(1):6

伴随着引力波事件GW170817的短暴GRB (Gamma-Ray Burst) 170817A首次提供了双中子星并合与短暴相联系的直接证据.但是短暴GRB 170817A具有非常弱的光度,意味着观测的视线方向可能偏离喷流轴方向.根据短暴静止系的峰值能量E_(p,i)和各向同性光度L_(iso)。之间的关系以及洛伦兹因子Γ和L_(iso)。之间的关系估算了短暴GRB 170817A以及长短暴GRB 060614观测角与喷流边缘的夹角θ'_(obs)和洛伦兹因子Γ,结果表明GRB 170817A的Γ=45±27,θ'_(obs)=2.2±0.5°,而GRB 060614的Γ=214±93,θ'_(obs)=0.5±0.1°.这个结果相当于GRB 170817A的正轴各向同性光度L_(iso,on)=(2.1±0.7)×10~(49) erg·s~(-1),比典型的短暴少2-3个数量级.GRB 060614的L_(iso,on)=(5.12±1.91)×10~(51) erg·s~(-1)与典型短暴相当.这意味着GRB 060614可能属于短暴类型,而GRB 170817A可能本质上就是一个弱暴.  相似文献   

东昆仑夏日哈木地区二长花岗岩年代学、地球化学特征及地质意义     

郭峰  王盘喜  卞孝东  冯乃琦 《中国地质调查》2020,7(6):51-60

东昆仑夏日哈木地区首次发现了早泥盆世二长花岗岩,对其开展年代学和地球化学特征研究,进一步探讨其岩石成因和构造地质背景。二长花岗岩锆石U-Pb年龄为(412.1±5.7) Ma(MSWD=0.95),形成于早泥盆世早期; 岩石为过弱铝质亚碱性花岗岩,富SiO₂(含量为71.41%~72.46%)、K₂O(含量为5.27%~6.16%),贫Fe₂O₃(含量为1.86%~2.05%)、P₂O₅(含量为0.08%~0.12%),富集轻稀土元素,具明显的负Eu异常; 在原始地幔标准化微量元素蛛网图上可以看出,岩石明显富集Rb、Th、Zr、Hf,强烈亏损Nb、Sr、P、Ti、Ba。夏日哈木地区二长花岗岩属于I型花岗岩,其源岩可能由幔源岩浆底侵加热下地壳岩石致其部分熔融而形成,处于由同碰撞向后碰撞转换的构造环境,说明东昆仑夏日哈木地区在早泥盆世早期已进入伸展阶段。  相似文献   

Accuracy assessment of NLCD 2011 percent impervious cover for selected USA metropolitan areas     

《International Journal of Applied Earth Observation and Geoinformation》2020

The emergence of high-resolution land cover data has created the opportunity to assess the accuracy of impervious cover (IC) provided by the National Land Cover Database (NLCD). We assessed the accuracy of the 900 m² NLCD2011 %IC for 18 metropolitan areas throughout the conterminous United States using reference data from 1 m² land cover data developed as part of the United States Environmental Protection Agency’s EnviroAtlas project. Agreement was assessed from two perspectives: 1) sensitivity to the size of the assessment unit used for the comparison, and 2) utility of NLCD %IC to serve as a proxy for high-resolution IC. The former perspective was considered because statistical relationships can be sensitive to assessment unit size and shape, and the latter perspective was considered because high resolution (reference) %IC data are not available nationwide. The utility of NLCD %IC as a proxy for the high resolution data was assessed for seven lattice (square) cell sizes ranging from 1 ha to 200 ha using four EnviroAtlas IC indicators: 1) %IC per 100 ha (1 km²); 2) %IC by Census block group; 3) %IC within a 15 m (radius) of the riparian zone, and; 4) %IC within a 50 m (radius) of the riparian zone. Agreement was quantified as per assessment unit deviation (NLCD %IC – reference %IC) and summarized as Mean Absolute Deviation (MAD) and Mean Deviation (MD) both within and across the 18 metropolitan areas. Ordinary least squares (OLS) regression (y = reference %IC and x = NLCD %IC) was also used to evaluate the quality of the NLCD %IC data. MAD was ≤ 5% for six of the seven lattice cell sizes. MAD was also ≤ 5% for Census block groups > 100 ha and for both riparian units. These results suggest that uncertainty attributable to the measurement of %IC was no greater than the uncertainty related to the effect of IC on aquatic resources that have been derived from studies of aquatic condition (e.g., benthic fauna) over a range of %IC. Overall, agreement was variable from one metropolitan area to the next. Agreement improved as assessment unit size increased and declined as the level of urbanization (NLCD %IC) increased. NLCD %IC tended to underestimate reference %IC overall, but NLCD %IC was sometimes greater than reference %IC in urbanized settings.  相似文献   

复杂地形景区三维导览图的设计与实现     

吴思锴  李百寿  郭家豪  李雪  张卫平 《北京测绘》2020,(1):38-43

为满足复杂地形景区对三维地图导览的需求,构建更为清晰的三维地图模型,提供良好的三维导览地图设计方案显得尤为重要。为了更好地与卫星影像进行贴合,DEM数据的采样密度要与卫星影像的分辨率一致。本文通过对比当下常用的四种空间插值方法的适用范围与运用特点,设置相关阈值及权重,直观比较了四种插值方法产生的插值结果,选择更适合复杂景区DEM插值的插值方法并对其进行精度提升,以此得到符合精度要求的DEM数据。最后利用相应地区的卫星影像进行地图投影及影像贴图,两种数据结合构建复杂景区的三维地图模型,给游客带来更为精确直观的定位信息和空间要素信息。  相似文献