Hydrothermal Zircon from a Newly Found Porphyritic Granite in the Dongping Gold Deposit in Northern Hebei,China: Evidence from Petrography and Hf Isotope Composition

正Objective Hydrothermal zircon is altered by hydrothermal fluids and sometimes shows"hydrothermal mineral"characteristics.Studying hydrothermal zircon in gold deposits can help understand the origins of the gold mineralization.The Hf isotope composition of zircon can be used to determine the properties of the original rock.However,most zircon Hf isotope studies focus on     

WGS84与ITRS基准转换参数估计及长期演化特性分析

针对在轨运行的GPS卫星,利用由NGA提供的WGS84框架下精密星历以及IGS提供的ITRS框架下的精密星历,采用7参数布尔沙模型,并结合不同卫星的星载原子钟的稳定性,在最小二乘准则下求取WGS84和ITRS之间的转换参数。在此基础上,为了得到较长时间尺度上转换参数的演化特性,首先采用EMD算法进行去噪,以使得数据更能反映参数变化的本质特性,然后在消除趋势项的基础上,对转换参数的时间序列进行谱分析,以探索其周期特性。利用NGA和IGS提供的2009-01-01~2012-06-30共1306d的精密星历,求取每天一组的坐标转换参数,分析其长期演化特性后发现:3个平移参数分别具有345d,690d和345d的周期项,3个旋转参数分别具有459d,172d和459d的周期项,尺度参数则不具有明显的周期项。     

一种遥感影像核变化检测方法

提出了一种新的遥感影像核变化检测方法。该方法是将原始空间不同时相的输入矢量通过核函数非线性映射到高维特征空间,然后在高维特征空间中通过传统变化检测方法处理得到新的输入矢量,最后通过半监督的单类支持向量机算法对新的输入矢量构造变化区域与非变化区域的最优分割超平面。试验证实,本文的核变化检测方法具有较高的检测精度和效率。     

土地利用信息图谱的研究及应用

在分析地学信息图谱的基础上,针对土地利用的特殊性,提出了县级土地利用信息图谱的研究方法与技术路线。以余姚市不同时期的土地利用数据库为依托,利用GIS技术建立土地利用变化信息图谱,并对该市的土地利用变化进行了分析研究。实例证明,这是一条有效的技术途径。     

基于多重变换组合的动态地图符号设计

采用面向对象的设计方法,将符号的状态描述(参量)与过程操作(对不同参量实施不同变换)封装,采用关键帧-层-图元-几何/非几何属性结构进行符号组织,从而将地图符号的时间维信息纳入到符号设计之中,建立了不同的变化速率模型,实现属性的动态变化;通过图元与图元之间的二维Morph函数变换矩阵,结合仿射变换,对符号的几何信息进行快速提取,从而实现了符号的动态显示。     

基于空间竞争的城市道路影响域划分方法研究

给出了道路网络多边形剖分的具体模型及算法,实现了城市道路影响域划分的自动化、智能化,为城市的交通状况评价及交通规划提供了科学依据。     

三频非组合模型的GPS/BDS/Galileo精密定轨

四大GNSS导航卫星系统发播三频及以上观测数据成为必然趋势.本文基于IGS钟差基准研究了三频非组合(UC)精密定轨模型及其模糊度固定方法.将载波相位硬件延迟分成时变和时不变参数,并进行参数重组,得到三频非组合定轨观测模型;类似精密定位中的超宽巷、宽巷、窄巷的分步模糊度固定策略,使用双差法推导了三频非组合模糊度固定方法....     

良庄井田地质构造特征及其对矿井突水的影响

根据大量地质资料揭示了山东良庄井田地质构造的发育特征,其断裂构造具有分区性、方向性、垂向分层性、成带性等特点,并推断井田内发育有滑动构造。探讨了该井田地质构造发育规律对矿井突水的影响,着重分析了滑动构造对矿井突水的作用。研究表明,断裂构造的分区性、方向性、垂向分层性、成带性及滑动构造对矿井突水有不同程度的影响。     

Characteristics of organic and elemental carbon in PM2.5 samples in Shanghai, China

Shanghai is the largest industrial and commercial city in China, and its air quality has been deteriorating for several decades. However, there are scarce researches on the level and seasonal variation of fine particle (PM_2.5) as well as the carbonaceous fractions when compared with other cities in China and around the world. In the present paper, abundance and seasonal characteristics of PM_2.5, organic carbon (OC) and elemental carbon (EC) were studied at urban and suburban sites in Shanghai during four season-representative months in 2005–2006 year. PM_2.5 samples were collected with high-vol samplers and analyzed for OC and EC using thermal-optical transmittance (TOT) protocol. Results showed that the annual average PM_2.5 concentrations were 90.3–95.5 μg/m³ at both sites, while OC and EC were 14.7–17.4 μg/m³ and 2.8–3.0 μg/m³, respectively, with the OC/EC ratios of 5.0–5.6. The carbonaceous levels ranked by the order of Beijing > Guangzhou > Shanghai > Hong Kong. The carbonaceous aerosol accounted for  30% of the PM_2.5 mass. On seasonal average, the highest OC and EC levels occurred during fall, and they were higher than the values in summer by a factor of 2. Strong correlations (r = 0.79–0.93) between OC and EC were found in the four seasons. Average level of secondary organic carbon (SOC) was 5.7–7.2 μg/m³, accounting for  30% of the total OC. Strong seasonal variation was observed for SOC with the highest value during fall, which was about two times the annual average.     

祁连山玉石沟橄榄岩岩浆作用的记录和铬铁矿的成因

祁连山玉石沟蛇绿岩型铬铁矿是典型的高铬型铬铁矿床.通过对玉石沟铬铁矿和橄榄岩围岩进行原位定距离采样研究表明:全岩高的MgO和低的SiO2含量指示这些蛇纹石化橄榄岩不是简单的部分熔融残余,而是经历了后期的熔体再富集作用.玉石沟近矿橄榄岩尖晶石(Cr#>65)和铬铁矿尖晶石的矿物包裹体化学特征反映矿体和围岩形成于俯冲带上覆岩石圈地幔.距离矿体由近及远,赋矿围岩尖晶石化学成分(Cr#=43.9~77.2,TiO2=0.06%~0.34%)无规律变化.这说明高铬型铬铁矿体成矿所需铬并非来源于围岩,而是与玻安质熔体渗滤有关.尖晶石含水矿物包裹体仅赋存在玉石沟铬铁矿尖晶石与硅酸盐矿物接触部位附近可能揭示了玉石沟铬铁矿体的成因:成矿铬尖晶石在上侵的含水熔体与周围方辉橄榄岩的反应过程中形成聚集.