Spatial and interannual variations in sedimentation patterns recorded in nonglacial varved sediments from the Canadian High Arctic

Multiple cores taken throughout Nicolay Lake in the Canadian High Arctic contain laminated sediments that are interpreted as varved. Annual sediment accumulation during the last 197 years reveals three major patterns that have important implications for hydroclimatic reconstruction. Widespread sediment dispersal is evident during most years and contrasts with years when anomalous localized and bifurcating patterns of deposition occur. Localized deposition is limited to the centre of the lake and is attributed to turbidity currents that originate on the delta foreslope. In contrast, a bifurcating pattern is produced when the river supplying the delta switches from one to two delta distributaries, resulting in altered proximal accumulation. Principal component analysis reveals additional accumulation anomalies that are sedimentologically indistinct, but constitute important sources of localized variance. The recognition and removal of anomalous deposition patterns is critical for accurate reconstruction of sediment flux from the catchment, particularly in long records where geomorphic conditions may have changed. This study identifies potentially misleading depositional artifacts and a methodology to recognize similar depositional controls in other lakes.     

ON2中部区域OH1667MHz脉泽的新观测

利用法国巴黎默东天文台的南锡射电望远镜对ＯＮ２ 中部区域ＯＨ１６６７ ＭＨｚ 脉泽首次进行观测．观测结果表明中部区域的ＯＨ１６６７ ＭＨｚ 脉泽的辐射频谱为典型的双峰结构．这说明ＯＮ２ 中部区域的ＯＨ１６６７ ＭＨｚ 脉泽是位于绕中央星运动的薄盘上．结合模型对中部区域的ＯＨ１６６７ ＭＨｚ 脉泽谱线频谱图进行分析和研究     

Evidence for the stratification of Fe in the photosphere of G191-B2B

The presence of heavy elements in the atmospheres of the hottest H-rich DA white dwarfs has been the subject of considerable interest. While theoretical calculations can demonstrate that radiative forces, counteracting the effects of gravitational settling, can explain the detections of individual species, the predicted abundances do not accord well with observation. However, accurate abundance measurements can only be based on a thorough understanding of the physical structure of the white dwarf photospheres, which has proved elusive. Recently, the availability of new non-local thermodynamic equilibrium model atmospheres with improved atomic data has allowed self-consistent analysis of the extreme ultraviolet (EUV), far UV and optical spectra of the prototypical object G191-B2B. Even so, the predicted and observed stellar fluxes remain in serious disagreement at the shortest wavelengths (below ≈190 Å), while the inferred abundances remain largely unaltered. We show here that the complete spectrum of G191-B2B can be explained by a model atmosphere where Fe is stratified, with increasing abundance at greater depth. This abundance profile may explain the difficulties in matching observed photospheric abundances, usually obtained by analyses using homogeneous model atmospheres, to the detailed radiative levitation predictions, particularly as the latter are only strictly valid for regions deeper than where the EUV/far UV lines and continua are formed. Furthermore, the relative depletion of Fe in the outer layers of the atmosphere may be evidence for radiatively driven mass-loss in G191-B2B.     

高精度重力资料在胜利油区油气藏探测中的应用

摘要：应用改进的重力归一化总梯度法（ＧＨ法）对胜利油田ＤＢ区的高精度重力测量资料进行了处理。计算了ＧＨ值在地下的三维分布。某一深度ＧＨ平面等值线图中的闭合极小值（ＧＨ低）反映了低密度体的存在及其水平位置,而不同深度等值线图中ＧＨ低的数目的变化可以近似表示低密度体集中的深度范围。ＧＨ平面等值线图还可以为选择ＧＨ铅垂断面图的方向提供依据。ＧＨ铅垂断面等值线图中的闭合极小值更清楚地显示出低密度体的形态及其近似深度。计算出的ＧＨ值的三维分布与钻井资料的比较表明,ＧＨ的闭合极小值与已知油气藏在位置上有较明显的相关关系。     

高温高压下成矿元素运移聚集模拟实验

通过不同温度和压力下岩块受力变形的模拟实验,证实了岩块受力变形导致成矿元素的迁移和富集,发现了高温高压下不同元素在同一温压条件下和同一元素在不同温压条件下具有不同的迁移和富集规律。实验表明,构造应力对许多内生金属矿产的形成、矿产中成矿元素的分带现象等都具有十分重要的作用。      

珠江口表层水中主要常量离子的研究

９９４年９月采集了珠江口表层海水水样,并对其溶解态的Ｋ＋、Ｎａ＋、Ｃａ２＋、Ｍｇ２＋、ＳＯ２－４、Ｃｌ等化学要素进行了测定。结果表明,珠江口调查海域表层水中溶解态的Ｋ＋、Ｎａ＋、Ｃａ２＋、Ｍｇ２＋、ＳＯ２－４主要受陆源淡水与外海水物理混合稀释的影响,与Ｃｌ具有良好的直线正相关;Ｃａ２＋／Ｃｌ、ＳＯ２－４／Ｃｌ明显高于大洋水相应比值,Ｎａ＋／Ｃｌ、Ｍｇ２＋／Ｃｌ略高,而Ｋ＋／Ｃｌ比大洋比值低;在与中国其它各主要河口表层水对应Ｃｌ比较中,珠江口的ＳＯ２－４／Ｃｌ较高,而Ｃａ２＋／Ｃｌ,Ｍｇ２＋／Ｃｌ比值居低;上述各主要常量离子和Ｃｌ的等值线均沿自北向南走向递增。     

重磁异常正反演可视化实时方法技术改进

摘 要 给出了2∙5D 多边形截面棱柱体重磁异常的简化表达式及其偏导数;提供了实用的可 视化模型建立、修改、实时正反演中的一些具体方法技术。借助这一操作方便、功能强大的 图形化实时反演系统‚资料解释工作者可以综合利用各种地质资料对计算过程实现引导和控 制‚使其解释思想及技术方案得到充分体现‚从而提高计算速度和质量。     

Short-term variabilities of upper ocean current in the warm pool region during TOGA/COARE IOP

Oceanic current data in the warm pool region of the western equatorial Pacific measured by upward-looking moored Acoustic Doppler Current Profilers at two equatorial sites (147°E and 154°E) and two off-equatorial sites (2°N and 2°S, 156°E) during TOGA/COARE Intensive Observing Period (IOP) from November 1992 to February 1993 are used to examine short-term variabilities in the upper layer above 160–240 m. In time series of the zonal and meridional currents in many layers, spectral peaks are found at periods around 2 days and 4 days in addition to high energies in a period range longer than 10 days. The signal with the period of about 2 days has significantly high energies at all sites, and its magnitude is higher for the meridional current than for the zonal one. This signal is especially active in the first half of IOP from November to December in 1992. In this period, the quasi-2-day signal in the current field is coherent between northern (2°N) and southern (2°S) stations, but it has no evident relationship with that in the surface wind field around the stations. The quasi-4-day signal with the period of about 4 days has highest energies in layers above 160 m at the southern station, and is coherent between northern and southern stations. Besides, the signal at the station of 2°S has a significantly high coherence with that in the wind at the southern station, suggesting that it is a local phenomenon.     

核电厂取水明渠泥沙回淤分析

核电厂需用大量冷却水,用水量为工业用水的第一位。明渠取水是核电厂常用的取水方式之一。本文针对电厂取水明渠及口门外水流特点,分析计算了取水明渠内各部位及口门外过渡段的泥沙回淤率,并提出减少明渠泥沙回淤量的措施。     

青藏高原东部长江流域盆地地表化学剥蚀通量剥蚀速率大气CO2净消耗率研究

2000-2002年期间,笔者对青藏高原东部长江流域溶质载荷分别进行了取样分析并对流域盆地化学剥蚀通量、剥蚀速率和大气CO2净消耗率进行了计算。结果表明,流域盆地化学剥蚀速率以河源区楚玛尔河最高为2.34×10^6mol/a/km^2,沱沱河最低为1.40×10^6mol/a/km^2,四大支流雅砻江为1.69×10^6mol/a/km^2,金沙江为1.74×10^6mol/a/km^2,大渡河为1.57×10^6mol/a/km^2,岷江为1.88×10^6mol/a/km^2;流域盆地ФCO2估算结果以大渡河最高为101.81×10^3mol/a/km^2,楚玛尔河最低为7.55×10^3mol/a/km^2,金沙江为44.38×10^3mol/a/km^2,雅砻江为69.64×10^3mol/a/km^2,岷江为81.90×10^3mol/a/km^2,沱沱河为21.90×10^3mol/a/km2^。并对长江流域地表化学剥蚀速率主要控制因素进行了讨论。