南海中北部陆缘横波速度结构及其构造意义

纵横波联合勘探可以得到更多关于岩石圈层岩性、物性等介质属性方面的信息,有效提高地壳物质组成的约束性.在纵波速度结构模型的基础上,通过射线追踪和走时拟合对OBS2006-3地震剖面径向分量的转换震相进行了横波速度结构模拟.结果表明:沉积层1、沉积层2的横波速度分别为0.7~0.9 km/s和1.6~1.7 km/s,波速比由2.64~3.16变化到2.41左右,较高的波速比表明沉积层固结程度不高;中生代沉积层横波速度由浅部的2.6 km/s增大到3.0 km/s,波速比为1.74~1.80;地壳中波速比为1.74~1.82,表明该剖面地壳为陆壳性质;下地壳高速层的横波速度为4.0~4.2 km/s,纵横波速比为1.73~1.78,揭示高速层的物质组成为铁镁质的基性岩,推断其与海底扩张停止之后的岩浆底侵作用有关.     

基于互联网房产数据的住宅容积率多尺度时空特征——以广州市为例

基于网络爬虫技术获取房产时空数据,结合时间序列和空间自相关分析方法,在“小区—街道—区级”多尺度上探索广州市住宅容积率时空模式与演化规律。结果表明：① 近三十年广州市居住空间呈现中心城区集聚开发—向南、北方向近郊区拓展—往南、北、东方向远郊区外扩的演变过程,容积率呈现波动式增长态势。② 随着房地产的快速发展,住宅容积率逐渐呈现显著的空间自相关特征,体现了住宅开发与规划有序性的提高。③ 区级尺度上容积率呈现较强的自相关性,越秀区与天河区为HH集聚区,从化区为LL集聚区。街道尺度上容积率呈现出显著的空间不均衡性,区位交通条件较好的街道成为容积率HH集聚区,而LL集聚区主要分布于生态旅游重镇。     

Geochronological framework and Pb, Sr isotope geochemistry of the Qingchengzi Pb–Zn–Ag–Au orefield, Northeastern China

The Qingchengzi orefield in northeastern China, is a concentration of several Pb–Zn, Ag, and Au ore deposits. A combination of geochronological and Pb, Sr isotopic investigations was conducted. Zircon SHRIMP U–Pb ages of 225.3 ± 1.8 Ma and 184.5 ± 1.6 Ma were obtained for the Xinling and Yaojiagou granites, respectively. By step-dissolution Rb–Sr dating, ages of 221 ± 12 Ma and 138.7 ± 4.1 Ma were obtained for the sphalerite of the Zhenzigou Zn–Pb deposit and pyrargyrite of the Ag ore in the Gaojiabaozi Ag deposit, respectively. Pb isotopic ratios of the Ag ore at Gaojiabaozi (²⁰⁶Pb/²⁰⁴Pb = 18.38 to 18.53) are higher than those of the Pb–Zn ores (²⁰⁶Pb/²⁰⁴Pb = 17.66 to 17.96; Chen et al. [Chen, J.F., Yu, G., Xue, C.J., Qian, H., He, J.F., Xing, Z., Zhang, X., 2005. Pb isotope geochemistry of lead, zinc, gold and silver deposit clustered region, Liaodong rift zone, northeastern China. Science in China Series D 48, 467–476.]). Triassic granites show low Pb isotopic ratios (²⁰⁶Pb/²⁰⁴Pb = 17.12 to 17.41, ²⁰⁷Pb/²⁰⁴Pb = 15.47 to 15.54, ²⁰⁸Pb/²⁰⁴Pb = 37.51 to 37.89) and metamorphic rocks of the Liaohe Group have high ratios (²⁰⁶Pb/²⁰⁴Pb = 18.20 to 24.28 and 18.32 to 20.06, ²⁰⁷Pb/²⁰⁴Pb = 15.69 to 16.44 and 15.66 to 15.98, ²⁰⁸Pb/²⁰⁴Pb = 37.29 to 38.61 and 38.69 to 40.00 for the marble of the Dashiqiao Formation and schist of the Gaixian Formation, respectively).Magmatic activities at Qingchengzi and in adjacent regions took place in three stages, and each contained several magmatic pulses: ca. 220 to 225 Ma and 211 to 216 Ma in the Triassic; 179 to 185 Ma, 163 to 168 Ma, 155 Ma and 149 Ma in the Jurassic, as well as ca. 140 to 130 Ma in the Early Cretaceous. The Triassic magmatism was part of the Triassic magmatic belt along the northern margin of the North China Craton produced in a post-collisional extensional setting, and granites in it formed by crustal melting induced by mantle magma. The Jurassic and Early Cretaceous magmatism was related to the lithospheric delamination in eastern China. The Triassic is the most important metallogenic stage at Qingchengzi. The Pb–Zn deposits, the Pb–Zn–Ag ore at Gaojiabaozi, and the gold deposits were all formed in this stage. They are temporally and spatially associated with the Triassic magmatic activity. Mineralization is very weak in the Jurassic. Ag ore at Gaojiabaozi was formed in the Early Cretaceous, which is suggested by the young Rb–Sr isochron age, field relations, and significantly different Pb isotopic ratios between the Pb–Zn–Ag and Ag ores. Pb isotopic compositions of the Pb–Zn ores suggest binary mixing for the source of the deposits. The magmatic end-member is the Triassic granites and the other metamorphic rocks of the Liaohe Group. Slightly different proportions of the two end-members, or an involvement of materials from hidden Cretaceous granites with slightly different Pb isotopic ratios, is postulated to interpret the difference of Pb isotopic compositions between the Pb–Zn–(Ag) and Ag ores. Sr isotopic ratios support this conclusion. At the western part of the Qingchengzi orefield, hydrothermal fluid driven by the heat provided by the now exposed Triassic granites deposited ore-forming materials in the low and middle horizons of the marbles of the Dashiqiao Formation near the intrusions to form mesothermal Zn–Pb deposits. In the eastern part, hydrothermal fluids associated with deep, hidden Triassic intrusions moved upward along a regional fault over a long distance and then deposited the ore-forming materials to form epithermal Au and Pb–Zn–Ag ores. Young magmatic activities are all represented by dykes across the entire orefield, suggesting that the corresponding main intrusion bodies are situated in the deep part of the crust. Among these, only intrusions with age of ca. 140 Ma might have released sufficient amounts of fluid to be responsible for the formation of the Ag ore at Gaojiabaozi.Our age results support previous conclusions that sphalerite can provide a reliable Rb–Sr age as long as the fluid inclusion phase is effectively separated from the “sulfide” phase. Our work suggests that the separation can be achieved by a step-resolution technique. Moreover, we suggest that pyrargyrite is a promising mineral for Rb–Sr isochron dating.     

2018年春季北京一次沙尘天气边界层特征及来源分析

2018年3月27—28日,内蒙古中东部、中国东北地区、华北等地出现一次大范围沙尘天气.28日凌晨,沙尘进入北京,受此影响北京出现了严重的污染天气.本文利用中国气象局地面常规观测资料、气溶胶激光雷达、风廓线雷达资料、生态环境部大气成分等资料分析了北京沙尘天气前后边界层特征、沙尘来源以及沙尘天气前后大气污染特征.结果表明...     

基于Ripley’s K函数的南京市ATM网点空间分布模式研究

运用Ripley’s K函数的相关理论,以南京市ATM网点为研究对象,分别从平面与网络空间两种视角,在中心城区范围与主城区范围两种空间尺度上,通过单变量\begin{array}{c}K\end{array}函数法分析ATM网点的分布模式,通过双变量\begin{array}{c}K\end{array}函数法分析ATM网点与地铁站点的空间关联情况,最后对计算结果进行评价与分析。研究表明,ATM网点在南京主城区与中心城区均呈现出较强的集聚状态;在一定的距离范围内,ATM网点与地铁站点之间也有较强的依赖关系。同时,对于沿着路网分布的地理空间点状对象而言,利用网络\begin{array}{c}K\end{array}函数法进行空间点模式分析比用平面\begin{array}{c}K\end{array}函数法更加符合实际情况。     

中国资源外交的地缘政治分析

资源外交寓于国际地缘政治的长期博弈之中。地缘政治是一国对外交往所要考虑的重要因素之一。本文立足于内线周边和外线外围的地缘关系分析,总结了中国资源外交地缘政治的总体态势和潜在风险,并试图提出我国资源外交的基本思路。在全球地缘政治格局中,中国的资源外交包括内线地带和外线地带两个层次：内线由接壤的邻国以及接近的近邻组成,是中国资源外交的战略依托地带;外线由涵盖美洲、欧洲、非洲和澳洲大陆的资源生产大国和消费大国组成,是中国资源外交的战略腾挪空间。在这两个层次上,我国的地缘风险主要来自其他大国的地缘战略遏制、“走出去”战略的地缘选择权旁落、资源通道和贸易路线受制于人。要突破这些地缘限制与束缚,我国的资源外交需统筹国内、国际两个大局,分清内线、外线战略方向的轻重缓急,以周边关系为首要、以大国关系为关键、以发展中国家关系为基础,积极拓展对外友好关系的发展空间,有序扩展资源合作领域,坚定维护国家资源权益。     

红层软岩模型试验相似材料的配比试验研究

相似模型试验是研究红层软岩工程性质的重要手段之一,其试验结果的可靠性依赖于相似材料的正确选择与合理配比。针对红层软岩遇水极易软化的特性,在传统相似材料配比基础上添加生石灰,采用正交设计方法开展了相似材料配比试验,以骨料中铁粉与钡粉质量比例、铁粉与钡粉总质量中铁粉的质量比例、石膏质量、生石灰质量为4个因素,每个因素设置了5个取值水平,共制作25组、610个试样。每组试样均测试了其软化系数、密度、无侧限单轴抗压强度、抗拉强度及黏聚力与内摩擦角等物理力学参数,并研究了这些参数随上述4个因素取值水平的不同而变化的规律。最后,基于上述结果,配制了3种典型的软岩相似材料,并分别开展了真实软岩材料的饱水软化平行对比试验。研究结果表明：（1）根据配比方案所配相似材料物理力学参数可基本满足软岩相似模型试验的要求;（2）相似材料物理力学参数变化规律明显,便于通过调节其配比模拟不同软岩材料;（3）三组对比试验中相似材料饱水软化系数与真实软岩具有较高吻合度。     

基于à trous小波变换的Landsat 7 ETM＋图像融合研究

 以胶州湾及周边海岸带为研究区，采用Landsat 7 ETM+数据，提出一种基于à trous小波变换的全色图像和多光谱图像融合改进算法。对全色图像和多光谱图像进行适当层数的小波分解，多光谱图像的低频部分采用全色图像和其低频分量的比来调制； 最高分解层外的其余分解层采用多光谱图像和全色图像在该层分解系数的加权和，加权系数由局部区域能量比来确定； 最高分解层则采用绝对值最大准则。实验表明，该方法得到的图像可提高空间分辨率，对多光谱图像的光谱信息扭曲也较小，为提高海岸带地物分类和信息提取精度奠定了基础。     

圆形断面管道非满流流速计算表达式

工程实际中,常需要计算某一充满度下管道非满流的流量及流速。目前大多数计算模型均采用水力半径作为反映过流断面形状及几何尺寸的特征参数。针对不同充满度的研究结果表明,这种类型模型的计算结果与真实的流动特性并不相符,尤其当水深接近管顶时。根据水动力学基本原理及试验研究手段,对圆形断面管道无压均匀流流量-充满度非单一性进行了探索,并提出了以流量作为形状特征参数的更为合理且简单实用的水流流速计算表达式。