孢粉记录揭示的4000 a BP来乌鲁木齐河源区气候环境变化

对乌鲁木齐河源大西沟气象站附近热融塌陷剖面的分析,重建了该区4000aBP以来的气候演变序列.结果表明:近4000aBP以来乌鲁木齐河源区气候经历了多次干湿变化,即4000～3630aBP为干暖期,3630～2270aBP为凉湿冷湿期,2270～2100aBP为干暖期,2100～1310aBP干暖转化为暖湿期,1310～1100aBP为干暖期,1100aBP至今是凉湿冷湿期.发现本区气候具有典型的西风带影响下的变化特征,遵循暖干同期、冷湿同期的规律;部分层位反映的暖湿气候说明东亚季风强盛时期,可以深入到乌鲁木齐河源地区.     

Pulsational properties of V2109 Cyg

In this study V2109 Cyg (a pulsating δ Scuti star) has been modelled. In treating the oscillation equations perturbation in gravitational potential energy has been taken into account. Both radial and nonradial oscillations are treated with adiabatic approximation. The so called radial fundamental frequency (5.3745 c/d) and the nonradial frequency (5.8332 c/d) were obtained within a satisfactory precision. It was found that the Cowling approximation introduced more error as one went from low overtones to high overtones in radial oscillations. A similar trend was observed in nonradial case with low values of l. By keeping the effective temperatures almost the same as with V2109 Cyg two more models with different masses have also been calculated to see the effect of inclusion of perturbation in gravitational potential energy on oscillation frequencies in different masses. Conclusion arrived is that one must be careful to employ the Cowling approximation especially for high nonradial oscillation frequencies. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Characteristics of δ13CDIC in lakes on the Tibetan Plateau and its implications for the carbon cycle

Dissolved inorganic carbon isotope (δ¹³C_DIC) is an important tool to reveal the carbon cycle in lake systems. However, there are only few studies focusing on the spatial variation of δ¹³C_DIC of closed lakes. Here we analyze the characteristics of δ¹³C_DIC of 24 sampled lakes (mainly closed lakes) across the Qiangtang Plateau (QTP) and identify the driving factors for its spatial variation. The δ¹³C_DIC value of these observed lakes varies in the range of ? 15·0 to 3·2‰, with an average value of ? 1·2‰. The δ¹³C_DIC value of closed lakes is close to the atmospheric isotopic equilibrium value, much higher than that in rivers and freshwater lakes reported before. The high δ¹³C_DIC value of closed lakes is mainly attributed to the significant contribution of carbonate weathering in the catchment and the evasion of dissolved CO₂ induced by the strong evaporation of lake water. The δ¹³C_DIC value of closed lakes has a logarithmic correlation with water chemistry (TDS, DIC and pCO₂), also suggesting that the evapo‐concentration of lake water can influence the δ¹³C_DIC value. The δ¹³C_DIC value shows two opposite logarithmic correlations with lake size depending on the δ¹³C_DIC range. This study suggests that the δ¹³C in carbonates in lacustrine sediments can be taken as an indicator of lake volume variation in closed lakes on QTP. Copyright © 2011 John Wiley & Sons, Ltd.     

福建紫金山矿田晚中生代英安玢岩形成时代及其成矿意义

福建紫金山Cu-Mo-Au-Ag多金属矿田是一个完整的斑岩-浅成低温热液矿床成矿体系。英安玢岩主要分布在紫金山Au-Cu矿床内火山机构及其附近,与高品位Au-Cu矿体空间上联系密切,是矿田内火山-侵入岩浆过程的一个重要环节。采自矿区的两个英安玢岩样品LA-ICP-MS锆石U-Pb定年结果分别为(105.0±0.7)Ma(MSWD=0.83)和(105.0±2.2)Ma(MSWD=1.70),其形成时代与区内Mo-Cu矿化的萝卜岭和四方岩体形成时代相近。三个岩体形成时代及地球化学特征的相似性表明它们应为同源岩浆演化的产物,它们均具有较高的锆石Ce4+/Ce3+值,即岩浆体系具有较高的氧逸度,与区内斑岩成矿体系巨量金属堆积的地质事实相一致。英安玢岩的精确定年表明,紫金山Cu-Au矿与萝卜岭Mo-Cu矿及四方岩体有关的Mo矿床为同一斑岩成矿体系的产物。     

EH-4电导率成像系统在铝土矿找矿中的应用研究

简要介绍了EH-4电导率成像系统的基本原理和工作方法。在河南省渑池县雷沟铝土矿区的找矿试验中,测试了系统的稳定性、垂向电性分层能力及对矿区典型电性结构的探测能力和复杂条件的适用能力。应用小波多分辨分析的数学方法对实测数据进行了一阶多分辨分解,分离出一阶细节异常和一阶逼近异常。比对矿区ZK808孔资料,说明了一阶细节异常包含了较多的噪声和静态效应,而一阶逼近异常包含有较多的目标地质体的异常信息,从而有效地压制了噪声及静态效应,突出了目标地质体的异常信息。采用一阶逼近数据进行二维联合反演,并将反演结果与矿区地质资料进行对比,肯定了EH-4电导率成像系统在铝土矿勘查中的找矿效果及应用前景。     

MN长度误差及方向偏差对EH4视电阻率的影响

在EH4工作中,MN误差会导致视电阻率误差。有学者曾推导出MN长度误差引起的视电阻率相对误差公式,但公式的推导过程与实际工作有一定的偏差。MN方向偏差、MN长度误差及方向偏差同时存在对EH4视电阻率的影响,却未见报道。因此,这里对MN长度误差、MN方向偏差、MN长度误差及方向偏差同时存在引起的EH4视电阻率相对误差进行理论推导和数值计算。研究表明,EH4视电阻率误差随着MN误差的增大而增大;当存在MN长度误差时,MN长度误差为负的视电阻率相对误差比MN长度误差为正时大。     

EH4仪器阻抗估算技术缺陷分析

基于StrataGem（EH4）大地电磁测量仪的实测数据,剖析了该系统计算阻抗过程（IMAGEM软件完成）中两个重要不足。一个是以常相干度为工具控制由机械叠加形成的原始谱而计算互功率谱过程,容易造成放大单个原始谱点在互功率谱计算中的作用,也可能舍弃了许多有用信息;另一个是以最小二乘算法估算阻抗容易造成所估算的阻抗不稳定。     

矿物中4He同位素提取和含量测定研究

(U-Th)/He定年是一种有效的低温热年代学定年技术,现已被广泛应用于地质研究的各个领域,而矿物中4He同位素的有效提取和含量准确测定是该技术的关键。磷灰石和锆石是(U-Th)/He定年最常用的矿物,其4He提取条件及铀钍含量测定方法都较为成熟;而其他矿物(如磁铁矿、橄榄石、针铁矿、石榴子石等)的研究则相对较少。文章介绍了当前国内外(U-Th)/He研究中采用的4He同位素提取方法———真空炉加热法和激光加热法,激光加热法因具有低4He背景值和耗时短的优点而成为主要的提取方法。以磷灰石样品测试为例,介绍了成都地质矿产研究所建立的采用激光加热法和四极杆质谱提取4He同位素及其含量测量过程、含量计算和校正方法。指出未来(U-Th)/He测试技术除继续改进现有分析方法外,应加强对更多不同矿物的测试研究。     

大型坳陷湖盆“洪水—河漫湖”沉积——以干旱背景下的松南泉四段为例

本文建立了一种干旱背景下坳陷湖盆全新的沉积充填模式,即"洪水—河漫湖"沉积模式。在干旱背景下,物源区的河流主要表现为季节性的洪水,大多数河流都消失在荒漠中,河水主要以地表蒸发、植被生态消耗、地下渗流、河流终端湖以及河漫湖等形式排泄,坳陷湖盆内并未形成统一大面积的汇水中心和湖相沉积。这种背景条件下,湖盆的沉积充填特征明显不同于经典的坳陷湖盆和浅水湖盆沉积。下白垩统泉头组四段沉积时期,松辽盆地具有气候干旱、地势平坦、生物单调贫乏等特征,盆地南部存在5大沉积体系及7条主要的水系。除在盆地西部古龙凹陷地区河流汇水形成小范围浅水湖泊外,在盆地南部主要为"洪水—河漫湖"的河流相沉积。坳陷湖盆"洪水—河漫湖"沉积具有以下特点:①全盆地没有统一的汇水中心,因而缺乏大面积分布的湖相和三角洲沉积;②河流表现为季节性的洪水,部分河流由于地形变缓,并未进入汇水中心,而是消失在荒漠中,河流相为盆地沉积充填的主要类型;③湖盆具有多物源、多漫湖、满盆含砂的沉积特点;④河漫湖与河流在空间分布上存在3种关系,即河流终止于河漫湖、河流穿过河漫湖、河流绕过河漫湖等。坳陷湖盆"洪水—河漫湖"是一种中—新生代陆相坳陷湖盆沉积充填的新模式,具有重要的理论和实践意义。     

Elemental abundance analyses with DAO spectrograms: XXXII. HR 6455 (A3 III), δ Aqr (A3 V), η Lep (F2 V), and 1 Boo (A1 V)

We examine the sharp‐lined stars HR 6455 (A3 III, v sin i = 8.7 km s^–1) and η Lep (F2 V, v sin i = 13.5 km s^–1) as well as δ Aqr (A3 V, v sin i = 81 km s^–1) and 1 Boo (A1 V, v sin i = 59 km s^–1) to increase the number consistently analyzed A and F stars using high dispersion and high S/N (≥200) spectrograms obtained with CCD detectors at the long Coudé camera of the 1.22‐m telescope of the Dominion Astrophysical Observatory. Such studies contribute to understanding systematic abundance differences between normal and non‐magnetic main‐sequence band chemically peculiar A and early F stars. LTE fine analyses of HR 6455, δ Aqr, and 1 Boo using Kurucz's ATLAS suite programs show the same general elemental abundance trends with differences in the metal richness. Light and iron‐peak element abundances are generally solar or overabundant while heavy element and rare earth element abundances are overabundant. HR 6455 is an evolved Am star while δ Aqr and 1 Boo show the phenomenon to different extents. Most derived abundances of η Lep are solar (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)