江陵凹陷新生代玄武岩水-岩反应模拟及其对富钾卤水成因的指示

关于江陵凹陷富钾卤水的物质来源和成因机理仍未查明. 对凹陷新生代玄武岩开展矿物学、岩石学、地球化学研究以及水-岩反应模拟实验,重点研究时间、温度、流体成分等对水-岩反应的影响. 结果表明,卤水具有高锂低镁的特征,说明其在成因上受到火山活动的影响;研究区岩浆发生不同程度的分异,玄武岩蚀变作用强烈,表明地下热液的交代作用强烈,玄武岩通过水-岩反应为富钾卤水矿提供了物质来源;温度是流体对元素的淋滤能力的主要控制因素,高盐度流体是各成矿元素主要的迁移载体,水-岩反应是卤水形成的重要过程.      

西沙群岛西科1井第四纪生物礁中典型暴露面的岩石学与孔隙特征

根据岩心观察、薄片鉴定和图像分析, 对西科1井第四纪发育的典型暴露面及其附近的岩石类型、成岩作用和孔隙类型进行了系统的分析.研究表明: 典型暴露面(埋深68.75~70.24 m)附近的岩石类型为骨架灰岩和泥粒灰岩, 成岩作用类型包括溶解作用、胶结作用、泥晶化作用和新生变形作用, 孔隙类型主要为粒间孔和粒间溶孔、粒内孔及粒内溶孔、生长骨架孔及其溶孔、铸模孔和晶间溶孔.碳酸盐矿物的悬垂状产状、生物体腔孔充填物的方解石化和普遍发育的溶解作用指示该深度段遭受了大气水淋滤的强烈改造.      

A mechanism for the origin and development of the large-scale dunefield on the right flank of the lower reach of Laoha River, Northeast China

By viewing satellite imagery, a striking large-scale dunefield can be clearly perceived, with a size of nearly 63 km long and 11 km wide, and trending NE–SW, on the right flank of the lower Laoha River, Northeast China. By means of remote sensing imagery analysis and field observation as well as a comparison with a small-scale dunefield on the right flank of the lower Xiangshui River, analogous to the case of the lower Laoha River, this paper presents a new mechanism for its origin and development. The results show that:(1) the large-scale dunefield bears a tile-style framework overwhelmingly composed of transverse barchanoid ridges perpendicular to the predominant winds, and inlaid diverse blowouts.(2) The small-scale dunefield, referred to as a primary structural unit of the large one, is typical of an incipient dunefield, following the same rules of evolution as the larger.(3) A succession of barchanoid ridge chains can steadily migrate downwind in much the same manner as surface wave propagation in air or water stimulated by an incised valley, and ultimately tend to bear roughly the same wavelength and amplitude under stable climate and hydrologic regimes.(4) The first ridge chain acquires its sand source substantially from the downwind escarpments exposing the loose Quaternary sandy sediments to the air, while the ensuing ridges derive their sands dominantly from in situ deflation of the underlain Quaternary loose sandy sediments in blowouts, partly from the upwind ridges through northern elongated horns. Theoretically, the sands from riparian escarpments can be transported by wind to the downwind distal end of a dunefield after sufficient long duration.(5) The lower Laohahe region experienced probably three significant climatic changes in the past, corresponding to the three active dune belts, suggesting that once a large-scale dunefield occurs, it is nearly impossible to be completely stabilized, at least in its central portions. At present, seasonal shrinkage and stagnation of the lower Laoha River, widespread farming and afforestation in the valley, and establishing windbreaks downwind of the valley as well as surrounding the dunefield, appear to have significantly modified local flow fields and sand sources, engendering significant degradation of the dunefield.     

2018年1月江苏3次致灾暴雪成因对比分析

应用常规天气图资料、FY-2E 云顶亮温(TBB)资料、多普勒雷达观测资料和NCEP/NCAR 1°×1°再分析资料,对江苏2018年1月3—4日(简称“01·04”过程)、1月24—25日(简称“01·25”过程)和1月27—28日(简称“01·27”过程)3次暴雪过程进行了对比分析。结果表明：1)3次暴雪过程都是在500 hPa高空槽、中低层切变线、700 hPa西南急流和地面冷空气的共同影响下产生的;暴雪过程中水汽主要来源于中层,降雪期间逆温层结始终存在。2)不同之处是,“01·04”过程中层暖湿气流先形成,水汽条件更好,而后弱冷空气自低层楔入,促使暖湿气流抬升,上升运动发展更为旺盛;“01·25”过程和“01·27”过程低层先形成冷垫,而后中层暖湿气流增强沿冷垫爬升,冷垫更冷,“01·25”过程逆温更强。3)暴雪过程中TBB稳定低值期基本可以反映强降雪时段;“01·04”过程中有弱对流发展,造成降雪强度大。     

Fractal properties of crater ejecta outlines on Venus

Fractal property or self-similarity exists abundantly in many aspects in our universe. Fractals are rich in geology and have certain relations to various geological processes. This article presents analyses of fractal properties of 18 impact crater ejecta margins on the surface of Venus. The structured walk method was used to measure the length of perimeter of the ejecta margin and the resulting Richardson plots were investigated. EveryR-plot has a first linear part, a second part and a main scattering part. The variations seen in the second part include information on the formation and geology of the crater ejectas. The fractal dimension of the second part is related to the perimeter of the ejecta and thus to the impact energy. The ratio of the square of the perimeter to the area describes the lobateness of the ejecta and has a positive correlation to the perimeter in a way similar to that between the fractal dimension of the second part and the perimeter. Two linear subparts in the second part indicate different fractal properties due to various processes dominating on different scales. Scattering in the middle of the second part indicates the scale and type of the ejecta lobes. The smooth scattering over the entire second part is related to impact angle and energy. A threshold value beyond which the structured walk method cannot be used was observed at a ruler length of about 1/10 of the perimeter.     

流体 花岗岩 金矿

流体地质研究是当代地学研究中的重要前沿课题，已成为发展地质科学、建立新的知识体系的一个主要支柱和知识生长点。本文阐述了当今国内外流体的研究现状、发展水平、流体的涵义、性质、研究方法和研究重点及其与板块构造、变质作用、岩浆作用、成矿作用、成矿作用的重要意义。流体地质为地质科学提出了许多新的研究机会和挑战。该文在简要评述当今花岗岩研究现状的基础上，对花岗岩与金矿的关系进行了深入的讨论，指出了不同成因类型的花岗岩与金矿有着完全不同的关系。人们所说的花岗岩与金矿关系多数情况下应考虑是流体作用的结果。最后指出加强流体地质研究对提高河南地质与金矿的研究水平具有十分重要的实际意义和理论意义。     

Circular Polarization in Pulsar Integrated Profiles： Updates

We update the systematic studies of circular polarization in integrated pulse profiles by Han et al. Data of circular polarization profiles are compiled. Sense reversals can occur in core or cone components, or near the intersection between components. The correlation between the sense of circular polarization and the sense of position angle variation for conal-double pulsars is confirmed with a much large database. Circular polarization of some pulsars has clear changes with frequency. Circular polarization of millisecond pulsars is marginally different from that of normal pulsars.     

Unusual spectral absorption observed in the 16 August 1989 limb flare

A relative complete set of He I 10830 Å profiles and their coincident slit-jaw Hα images of the large limb flare (2N/X20) of 16 August 1989 were observed by the solar spectrograph at Purple Mountain Observatory. In addition to the unusually broadened spectral profiles observed in the impulsive phase, more than half of the observed He I 10830 Å profiles are characterized by central reversals, which were detected not only in the impulsive phase but also in the late decaying phase. The central-reversed profiles may exist at different heights, ranging from the solar limb to (3–4) × 10⁴ km above. The absorption varies with time and position, with a typical lifetime and size of several minutes and 5–6 arc sec, respectively. Depths of the absorption profiles also change clearly. The absorptions are usually deeper at the loop footpoint near the solar limb and shallower at loop-top. However, the most unusual feature is that all the line-center wavelengths of them show no shift relative to that of the quiet chromosphere near the limb, implying the apparent velocities are zero while the associated emission profiles have different apparent velocities. Theoretical simulations demonstrate that the Doppler widths of the absorptions are in the range of (0.35–0.5)Å and increase with height, and the source functions are (0.11–0.3) times the disk center intensity. However, the absorptions have a relative large range of optical thickness (0.1–1.3) in the I ₃ component of the He I 10830 Å triplet. We have not observed such absorption in other limb flares, including the SB/X2.9 flare of 17 August 1989 that occurred in the same active region as the studied one (NOAA 5629). Our studies show that the absorption could not result from he scattering by the telluric atmosphere or from normal chromospheric absorption. This unique phenomenon may be related to extra intense X-ray flux and caused by diffuse and non uniform materials dissociated from the flare instead of self-absorption of the flare.     

Calculation of the structure and transition probabilities of low energy levels of Fe and Fe

We use analytical wave functions in intermediate coupling to make a complete relativistic calculation of the structure and transition probabilities for the n = 1, 2, 3 states of Fe⁺²⁴. Data for Fe⁺²⁵ are also given for comparison. The results have a high accuracy and those relating to the n = 3 state are given in detail for the first time here.     

一株H_5N_1亚型禽流感病毒株NA基因的克隆与序列分析

用RT-PCR方法从1个H5N1亚型禽流感病毒分离株A/Chicken/Guangdong/DH/1997扩增NA基因cDNA片段,将其克隆至pMD18-T载体,获得重组质粒pMD-NA,并对其核苷酸序列进行测定和分析。结果表明,该毒株的NA基因长度为1350bp,编码449个氨基酸,与其它H5N1亚型AIV分离株的核苷酸序列同源性为97.0%～99.4%,氨基酸序列同源性为97.7%～99.1%,提示禽流感病毒NA基因保守性较高。NA基因氨基酸序列的聚类分析表明该毒株与来自香港的A/Pheasant/HK/FY155/01和A/Ch/HK/FY150/01两个分离株处于同一进化枝,亲缘关系较近。