Valence state partitioning of V between pyroxene‐melt: Effects of pyroxene and melt composition,and direct determination of V valence states by XANES. Application to Martian basalt QUE 94201 composition     

J. M. KARNER  J. J. PAPIKE  S. R. SUTTON  C. K. SHEARER  P. BURGER  G. McKAY  L. LE 《Meteoritics & planetary science》2008,43(8):1275-1285

Abstract— Experiments on a Martian basalt composition show that D_v augite/melt is greater than D_v pigeonite/melt in samples equilibrated under the same fO₂ conditions. This increase is due to the increased availability of elements for coupled substitution with the V³⁺ or V⁴⁺ ions, namely A1 and Na. For this bulk composition, both A1 and Na are higher in concentration in augite compared with pigeonite; therefore more V can enter augite than pigeonite. Direct valence state determination by XANES shows that the V³⁺ and V⁴⁺ are the main V species in the melt at fO₂ conditions of IW‐1 to IW+3.5, whereas pyroxene grains at IW‐1, IW, and IW+1 contain mostly V³⁺. This confirms the idea that V³⁺ is more compatible in pyroxene than V⁴⁺. The XANES data also indicates that a small percentage of V²⁺ may exist in melt and pyroxene at IW‐1. The similar valence of V in glass and pyroxene at IW‐1 suggests that V²⁺ and V³⁺ may have similar compatibilities in pyroxene.  相似文献   

Partially Fused Granite Blocks from Mt. Elephant, Victoria, Australia     

LE MAITRE  R. W. 《Journal of Petrology》1974,15(2):403-412

Petrological and chemical evidence is presented to show thatsmall patches of brown glass found in blocks of granite eruptedin basaltic scoria at Mt. Elephant are the result of the partialfusion of biotite and quartz. The glass has moderate SiO₂ (63–66per cent), high AI₂O₃ (17.5–19 per cent), high FeO (3.8–5.2per cent) and very high K₂O (7.0–7.8 per cent) relativeto Na₂O (3.3–3.7 per cent) and is similar in compositionto many high K alkali syenites and trachytes.  相似文献   

广西大瑶山地区加里东期石英脉型金矿：上木水金矿白云母Ar-Ar年龄约束          下载免费PDF全文

李忠阳  党院  乐兴文 《高校地质学报》2018,24(5):637

石英脉型金矿是广西大瑶山地区主要的金矿床类型之一,但一直没有高精度的年龄数据约束其成矿时代。论文首次 对大瑶山南部广西苍梧县上木水石英脉型金矿中的热液白云母进行39Ar/40Ar年龄法测年,获得坪年龄为（432.6 ± 3.2）Ma,相应 的等时线年龄为（428.2 ± 7.2）Ma,反等时线年龄为（425.3 ± 6.6）Ma,表明其成矿时代为加里东期。这一数据进一步证明 大瑶山南部的古龙-夏郢环形成矿区主要以加里东期矿化为主,除了与加里东期岩浆岩有关的斑岩-矽卡岩型钨多金属矿化 外,还存在石英脉型金矿。同时,位于大瑶山中部沿区域性大黎断裂分布的六岑-桃花-古袍金矿田的石英脉型金矿时代仍 然不明确,还需要进一步的高精度测年数据来约束。  相似文献   

2009年冬季南海北部浮游植物粒度分级生物量和初级生产力          下载免费PDF全文

曾祥茜  乐凤凤  周文礼  蔡昱明  郝锵 《海洋学研究》2017,35(3):67-78

2009年2月在南海北部海域现场观测粒度分级叶绿素a质量浓度和初级生产力(PP)的分布。结果表明,调查海域水柱平均叶绿素a质量浓度的变化范围为0.11～8.37 mg/m³,平均为(1.28±2.23) mg/m³,高值区出现在珠江口及近岸海域;初级生产力的范围为344.8～1 222.5 mgC/(m²·d),平均为(784.2±351.4) mgC/(m²·d),高值区位于近岸及陆架海域。浮游植物粒度分级测定结果表明,在生物量较高的近岸海域,叶绿素a的粒级结构以小型浮游植物占优势,其贡献率为40.9%,微型和微微型浮游植物对总叶绿素a的贡献率分别为34.6%和24.5%;而在生物量较低的陆坡和开阔海域,各粒级浮游植物对叶绿素a的贡献率由大到小依次为微微型浮游植物(78.9%),微型浮游植物(17.2%)和小型浮游植物(3.9%)。相关性分析结果表明,调查海域分级叶绿素a的区域化分布特征与洋流运动下营养盐的分布密切相关,同时叶绿素a又高度影响着此区域PP的分布。此外,我们将调查海域实测所得浮游植物最佳光合作用速率与采用垂向归一化初级生产力模型估算的数据进行对比,发现后者明显低于前者,这说明通过水温估算最佳光合作用速率的算法在冬季南海北部可能存在低估。  相似文献   

中国东部地区冬季气温与北极涛动的关系     

雷杨娜  孙娴  乐章燕 《气象与环境学报》2014,30(4):42-48

利用NCEP/NCAR再分析资料、北极涛动（AO）指数序列及中国160个台站月温度资料,分析1951-2007年中国冬季气温与AO指数的变化特征及其相互关系。结果表明：1951-2007年AO与中国东部地区冬季气温基本呈正相关关系。中国东部地区冬季气温指数（IWT）与北极涛动指数（IAO）均逐渐增强,并有显著的年际和年代际变化,均存在准18 a的周期变化特征。从偏相关系数来看,在年际尺度上,西伯利亚高压对中国东部地区冬季气温的年际变化影响较大,而AO与冬季气温无显著相关关系;在年代际尺度上,AO对中国东部地区冬季气温的影响较显著,比西伯利亚高压影响大。东亚大槽偏弱时,中国冬季气温偏高,AO指数也偏高,反之则相反。在年际尺度上,东亚大槽对中国东部地区冬季气温的年际变化影响较大,而AO与冬季气温无显著相关关系;在年代际尺度上,AO和东亚大槽对中国冬季气温的变化影响均较显著。  相似文献   

华北平原冬小麦根系在土壤中的分布研究   总被引：4，自引：0，他引：4  

廖荣伟  刘晶淼  白月明  安顺清  梁宏  卢建立  乐章燕  曹玉静 《气象与环境学报》2014,30(5):83-89

小麦根系在土壤中的分布是准确量化植被与气候相互作用不可缺少的参数,也是小麦生产的科学管理和节水农业发展的重要科学依据。利用中国气象局固城生态环境与农业气象试验站大型根系观测系统,观测冬小麦“济麦-22”的根系参数,对根长、根长密度、根重密度和根系粗度在土壤中的垂直分布进行分析。结果表明：垂直方向上,冬小麦的根量（根长和根干重）随土壤深度增加呈减少分布。重旱、轻中旱、适宜和偏湿4种处理的根长垂直分布与自然对照的相关系数分别为0.91、0.29、0.90和0.86,其中重旱与自然对照的相关性最好,轻中旱较差。土壤水分可以影响冬小麦根系的生长。土壤水分充足时,有利于根系生长,使表层根系量增多,根干物质量增加;土壤水分亏缺时,则相反。轻度干旱有利于中下层根系的延伸生长。冬小麦的根长密度与根重密度的相关系数呈显著的正相关,根系粗度随土壤深度的增加减少。  相似文献   

黄东海浮游生物群落呼吸率对碳平衡的重要性     

叶文琪  刘诚刚  蔡昱明  翟红昌  乐凤凤  王斌  寿鹿  陈全震  杜萍 《海洋与湖沼》2022,53(1):84-95

黄东海接受长江冲淡水和黑潮带来的大量营养盐和有机物质,其碳循环对陆架海碳源汇格局至关重要.浮游生物群落呼吸是影响碳循环的重要过程.为揭示黄东海浮游生物群落呼吸率(PCR)对碳平衡的贡献,于2011年四季使用黑白瓶培养法测定黄海南部及东海北部浮游群落呼吸率和初级生产力,并同步测定温度、盐度、营养盐、叶绿素和细菌丰度等环境...  相似文献   

Offshore Absolute Calibration of Space-Borne Radar Altimeters     

GWENAëLE JAN  YVES MÉNARD  MATHILDE FAILLOT  FLORENT LYARD  ERIC JEANSOU  PASCAL BONNEFOND 《Marine Geodesy》2013,36(3-4):615-629

Absolute calibration of sea level measurements collected from space-borne radar altimeters is usually performed with respect to collocated sea level in situ records from tide gauges or GPS buoys (Ménard et al. 1994 Ménard, Y., Jeansou, E. and Vincent, P. 1994. Calibration of the TOPEX-Poseidon altimeters at Lampedusa: Additional results at Harves. J. Geophys Res., 99(C12): 24487–24504. http://dx.doi.org/10.1029%2F94JC01300 [Google Scholar]; Haines et al. 1996 Haines, B. J., Christensen, E. J., Norman, R. A., Parke, M. E., Born, G. H. and Gill, S. K. 1996. Altimeter calibration and geophysical monitoring from collocated measurements at the Harvest oil platform. EOS Trans. Suppl., 77(22): W16 [Google Scholar]; Bonnefond et al. 2003; Haines et al. 2003 Haines, B. J., Dong, D., Born, G. H. and Gill, S. K. 2003. The Harvest experiment: Monitoring Jason-1 and TOPEX/Poseidon from a California offshore platform. Mar. Geod., 26: 239–259. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]; Schum et al. 2003 Schum, C. K., Yi, Y., Cheng, K., Kuo, C., Braun, A., Calmant, S. and Chambers, D. 2003. Calibration of Jason-1 Altimeter over Lake Erie. Mar. Geod., 26: 335–354.  [Google Scholar]; Watson et al. 2003 Watson, C., Coleman, R., White, N., Church, J. and Govind, R. 2003. Absolute calibration of TOPEX/ Poseidon and Jason-1 using GPS buoys in Bass Strait, Australia. Mar. Geod., 26: 285–304. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]; Watson et al. 2004 Watson, C., White, N., Coleman, R., Church, J., Morgan, P. and Govind, R. 2004. TOPEX/Poseidon and Jason-1: Absolute calibration in Bass Strait, Australia. Mar. Geod., 27: 107–131. http://dx.doi.org/10.1080%2F01490410490465373[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]). Such a method allows regular and long-term control of altimetric systems with independent records. However, this approach is based on a single, geographically dependent point. In order to obtain more significant and accurate bias and drift estimates, there is a strong interest in multiplying the number of calibration opportunities. This article describes a method, called the “offshore method” that was developed to extend the single-point approach to a wider regional scale. The principle is to compare altimeter and tide gauge sea level data not only at the point of closest approach of an overflying pass, but also at distant points along adjacent satellite passes. However, connecting sea level satellite measurements with more distant in situ data requires a more accurate determination of the geoid and mean ocean dynamic topography slopes, and also of the ocean dynamical changes. In this demonstration experiment, 10 years of averaged TOPEX/Poseidon mean sea level profiles are used to precisely determine the geoid and the mean ocean circulation slope. The Mog2d barotropic ocean model (Carerre et Lyard 2003 Carrère, L. and Lyard, F. 2003. Modelling the barotropic response of the global ocean to atmospheric wind and pressure forcing-comparisons with observations. GRL, 30(6): 1275 [Google Scholar]) is used to improve our estimate of the ocean dynamics term. The method is first validated with Jason-1 data, off Corsica, where the dedicated calibration site of Senetosa provides independent reference data. The method is then applied to TOPEX/Poseidon on its new orbit and to Geosat Follow On. The results demonstrate that it is feasible to make altimeter calibrations a few tens to hundreds of kilometers away from a dedicated site, as long as accurate mean sea level altimeter profiles can be used to ensure the connection with reference tide gauges.  相似文献   

某外海工程超长大直径钢管桩变形原因简析与加强方案研究     

徐定山  梁胜发  乐治齐 《海洋工程》2012,30(2):136-142

某外海工程在沉设超长大直径钢管桩施工过程中,发生钢管桩在海床泥面附近严重变形的情况。通过对本工程超长大直径钢管桩产生变形的可能性原因进行分析,同时对其变形处局部加强处理方案进行一系列的研究论证,并对加强处理方案进行比选优化后,最后采用一可靠的加强处理方案。为类似工程避免发生此类质量事故和钢管桩局部变形水下加强处理提供参考。  相似文献   

不同浓度悬浮泥沙水体的光谱吸收特性模拟     

孙德勇  李云梅  王桥  乐成峰  黄昌春  王利珍 《地理与地理信息科学》2008,24(5)

悬浮泥沙的光学特性是影响内陆湖泊水色遥感的重要因素。利用光谱吸收衰减仪(AC-S)测得水池中悬浮泥沙浓度为2.13~1 442.40 mg/L的水体光谱吸收。在蓝、绿和红光波段,悬浮泥沙水体的平均比吸收系数分别为0.0161±0.0039 m2.g-1、0.0071±0.0020 m2.g-1和0.0025±0.0007 m2.g-1;指数拟合获得的Sm*值为0.0098±0.0011 nm-1,利用其模拟的比吸收光谱与实测光谱吻合效果较好,说明该Sm*取值对悬浮泥沙水体比吸收光谱的曲线斜率变化具有一定的参考价值。此外,建立了悬浮泥沙水体吸收系数a(440)m与其浓度的关系模型,R2达0.947,拟合精度较高;然而比吸收系数a*(440)m与泥沙浓度几乎无相关性。研究结果可为内陆水色遥感分析模型的建立提供重要的参数保障。  相似文献